Kurzgesagt – In a Nutshell
Kurzgesagt – In a Nutshell
Embedded Files
Sources – Cannabis
Sources – Cannabis
We thank the following experts for their input:
– Dr. Will Lawn
King's College London
We thank the following experts for their input:
– Dr. Will Lawn
King's College London
– Dr. Matthew Hill
University of Calgary
– Dr. Matthew Hill
University of Calgary
– Dr. Rachel Lees
University of Bath
– Dr. Rachel Lees
University of Bath
– Cannabis has been vilified to a ridiculous degree for the last century, but is now finally being decriminalized in more and more places around the world – just recently legalized in Germany.
– Cannabis has been vilified to a ridiculous degree for the last century, but is now finally being decriminalized in more and more places around the world – just recently legalized in Germany.
As of 2024, the legal status of cannabis in different countries is depicted in the following map.
– And for very good reasons! Compared to legal drugs like alcohol – which will cause one in twenty deaths just this year, cannabis is pretty mild.
– And for very good reasons! Compared to legal drugs like alcohol – which will cause one in twenty deaths just this year, cannabis is pretty mild.
It is not straightforward to make direct comparisons among harm inflicted by different drugs since they have different levels of personal and social harm, as well as different prevalence. In the simplest case of toxicity for example we know that alcohol is actually toxic for our cells and classified as carcinogenic, so there is not any level of alcohol that is good for our body.
In the following study for example alcohol was ranked as the most harmful drug in the UK in a list followed by drugs like cocaine and heroin.
#Nutt DJ, King LA, Phillips LD; Independent Scientific Committee on Drugs. Drug harms in the UK: a multicriteria decision analysis. Lancet. 2010
https://pubmed.ncbi.nlm.nih.gov/21036393/
Quote: “Findings MCDA modelling showed that heroin, crack cocaine, and metamfetamine were the most harmful drugs to individuals (part scores 34, 37, and 32, respectively), whereas alcohol, heroin, and crack cocaine were the most harmful to others (46, 21, and 17, respectively). Overall, alcohol was the most harmful drug (overall harm score 72), with heroin (55) and crack cocaine (54) in second and third places.”
#Alcohol. WHO. 2022.
https://www.who.int/news-room/fact-sheets/detail/alcohol
Quote: “Worldwide, 3 million deaths every year result from harmful use of alcohol. This represents 5.3% of all deaths.”
One might think that alcohol is way more prevalent, socially acceptable and easier to access compared to other drugs and that’s why the harm it causes is greater. But that’s also one of the reasons which makes it one of the deadliest drugs.
#Uwe Fuhr. Clinical Pharmacology at University Hospital Cologne. What is more harmful – alcohol or cannabis? 2024.
Quote: “The dangers of an addictive drug do not only depend on the substance consumed, but also on the type, extent and conditions of use. At least in the case of the ‘Western world’, it currently seems obvious that alcohol is much more dangerous than cannabis. Studies from countries such as the United Kingdom and New Zealand have used scales to categorize the harmful consequences caused by drug addiction which include fatalities, health damage, functional impairment, addiction, accidents, crimes, social harm and financial harm. The scale values of alcohol are about three times higher than for cannabis.
[...]
Pharmacologically, a major difference is that alcohol is toxic to cells in addition to the specific effects in the central nervous system. Alcohol and its main degradation product acetaldehyde primarily damage the brain, liver, pancreas and heart directly. Alcohol consumption also increases the risk of various cancers. Tetrahydrocannabinol can also cause irreversible damage to the central nervous system, especially with prolonged use. Compared to alcohol, however, the use of cannabis has a non-specific toxic effect at most through the inhalation of combustion products when smoking joints, which plays a subordinate role compared to the non-specific toxic effect of alcohol.
Alcohol and cannabis are therefore both dangerous addictive substances that need to be handled carefully by the individual and by society. However, if you consider all factors, alcohol is more dangerous.”
– Naturally there was a lot of pushback and here something went wrong. If you followed the discourse in the last few years, you could get the impression that weed has almost only upsides and few, if any, negative side effects. We ourselves contributed to that narrative.
– Naturally there was a lot of pushback and here something went wrong. If you followed the discourse in the last few years, you could get the impression that weed has almost only upsides and few, if any, negative side effects. We ourselves contributed to that narrative.
According to the following report from WHO, the perception of risk regarding regular cannabis use has been on a decreasing trend in the USA and Europe which has been associated with an increased prevalence of use in adolescents.
#World Drug Report 2021 (United Nations publication, Sales No. E.21.XI.8).
https://www.unodc.org/res/wdr2021/field/WDR21_Booklet_3.pdf
Quote: “In recent years, the debate about medical use of cannabis and measures allowing non-medical use of cannabis in the United States and elsewhere have led adolescents to perceive cannabis as less harmful than they previously had.42 How much this reduced perception of harmfulness explains the long-term increase in cannabis use among adolescents is difficult to determine. It is clear, however, that there is an association between a lower perception of risk and higher use of cannabis, as observed in the United States, Europe and Latin America and the Caribbean, although the strength of the association, at least in the case of United States, may no longer be as strong as it used to be. The strength of this association may vary but, in both the United States and Europe, it is characterized by a steady decline in the risk perception of cannabis among adolescents and a long-term increase in regular cannabis use, with some irregular annual fluctuations.”
#Ishida JH, Zhang AJ, Steigerwald S, Cohen BE, Vali M, Keyhani S. Sources of Information and Beliefs About the Health Effects of Marijuana. J Gen Intern Med. 2020
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6957653/
Quote: “Unlike the growth of the tobacco industry, which came of age prior to the advent of the Internet, the marijuana industry has the opportunity to promote its expansion with marketing on the Internet and social media, where regulation is minimal and relatively undefined.36, 43, 44 Despite policies restricting marijuana advertising on Facebook and Google,45 prior work has demonstrated the predominance of positive messaging about marijuana and normalization of its use on Twitter and other Internet sources (e.g., YouTube, Instagram).43, 46, 47 Furthermore, there is an abundance of articles listing unproven health benefits of marijuana on the Internet, many targeting consumers in different countries.8, 48, 49 Given the extent of misinformation about marijuana on the worldwide web, it is not surprising that adults who believed misinformation were more likely to obtain information from social media and the Internet. Public health campaigns that use social media are necessary to combat misinformation about marijuana.”
We also made a video a few years ago
https://www.youtube.com/watch?v=kP15q815Saw
– Cannabis magic juice is Tetrahydrocannabinol, THC. It docks on your cannabinoid receptors, which affects various brain functions. THC activates some regions and calms down others, creating a fun cocktail of sensations.
– Cannabis magic juice is Tetrahydrocannabinol, THC. It docks on your cannabinoid receptors, which affects various brain functions. THC activates some regions and calms down others, creating a fun cocktail of sensations.
The main psychoactive molecule in cannabis is Δ9-tetrahydrocannabinol (Δ9-THC) which mainly interacts with cannabinoid receptor CB1R that is abundantly found in the brain but also elsewhere in the body. CB1R is located mainly in the cingulate gyrus, hippocampus, cerebellum, cortex, and basal ganglia, which are regions involved in functions like cognition, memory, motor control, reward processing. Activation of CB1 receptor moderates the release of other neurotransmitters from the pre-synaptic neuron like dopamine, glutamate and gaba. It therefore acts as a homeostatic dial on the function of other neurotransmitters. So instead of transmitting information to the next neuron, CB1 contributes to a feedback loop, more like a control mechanism. THC itself does only activate CB1 which in turn causes activation or inhibition of a wide range of neurons. In the abscence of THC, molecules that are normally produced in our bodies bind to CB1R and keep everything in check. But flooding that system with an external modulator interferes with the balance and disrupts the functions of these endogenous molecules. We are not getting into the details of the neural mechanisms in this video but we added a review paper below for further reading on it.
#Connor JP, Stjepanović D, Le Foll B, Hoch E, Budney AJ, Hall WD. Cannabis use and cannabis use disorder. Nat Rev Dis Primers. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8655458/pdf/nihms-1754902.pdf
Quote: “In this Primer we use ‘cannabis’ to refer to the cannabis plant material or its extracts that contain substantial amounts of Δ9 -tetrahydrocannabinol (THC), the compound that interacts with the cannabinoid CB1 receptor in the brain to produce the euphoric effects (the ‘high’) sought by people who use cannabis7,8. The ‘high’ can produce a desire for repeated use, which in some users develops into CUD9. People who use cannabis may mistakenly believe that cannabis does not produce a dependence syndrome or withdrawal symptoms; however, the effects of regular cannabis use on the endocannabinoid system and a considerable body of behavioural and clinical research indicate otherwise. In addition, CUD occurs in approximately 1 in 10 regular users and as many as one-third of those who use daily1. Persons with CUD also have higher risks of poor mental health, psychoses and bronchitis10.”
#Zou S, Kumar U. Cannabinoid Receptors and the Endocannabinoid System: Signaling and Function in the Central Nervous System. Int J Mol Sci. 2018
https://pmc.ncbi.nlm.nih.gov/articles/PMC5877694/
– The more THC, the more intense the high. And people seem to be into higher highs, or at least this is what the market provides. In the US, Canada and in Europe the concentration of THC in legal and illegal Cannabis products has more than doubled in the last few decades.
– The more THC, the more intense the high. And people seem to be into higher highs, or at least this is what the market provides. In the US, Canada and in Europe the concentration of THC in legal and illegal Cannabis products has more than doubled in the last few decades.
Following study investigated the potency in THC containing products (marijuana, sinsemilla hashish, hash oil) seized from the illegal markets in the US. They found that the increased prevalence of high potency products like sinsemilla contributed to the increases in the THC percentage. There is no single study reporting global numbers and most studies we found are from the US and report different numbers but they all point to an increase. We added a few publications below.
#World Drug Report 2021 (United Nations publication, Sales No. E.21.XI.8).
#Chandra S, Radwan MM, Majumdar CG, Church JC, Freeman TP, ElSohly MA. New trends in cannabis potency in USA and Europe during the last decade (2008-2017). Eur Arch Psychiatry Clin Neurosci. 2019
https://pubmed.ncbi.nlm.nih.gov/30671616/
Quote: ”Through the potency monitoring program at the University of Mississippi supported by National Institute on Drug Abuse (NIDA), a total of 18108 samples of cannabis preparations have been analyzed over the last decade, using a validated GC/FID method. The samples are classified as sinsemilla, marijuana, ditchweed, hashish, and hash oil (now referred to as cannabis concentrate). The number of samples received over the last 5 years has decreased dramatically due to the legalization of marijuana either for medical or for recreational purposes in many US states. The results showed that the mean Δ9-THC concentration has increased dramatically over the last 10 years, from 8.9% in 2008 to 17.1% in 2017. The mean Δ9-THC:CBD ratio also rose substantially from 23 in 2008 to 104 in 2017. There was also marked increase in the proportion of hash oil samples (concentrates) seized (0.5–4.7%) and their mean Δ9-THC concentration (6.7–55.7%) from 2008 to 2017. Other potency monitoring programs are also present in several European countries such as The Netherlands, United Kingdom, France, and Italy. These programs have also documented increases in Δ9-THC concentrations and Δ9-THC:CBD ratios in cannabis. These trends in the last decade suggest that cannabis is becoming an increasingly harmful product in the USA and Europe.”
#Rosalie Liccardo Pacula, Seema (Choksy) Pessar, Joy Zhu and Rosanna Smart. Federal Regulations of Cannabis for Public Health in the United States. 2022.
https://healthpolicy.usc.edu/research/federal-regulations-of-cannabis-for-public-health-in-the-u-s/
#ElSohly MA, Chandra S, Radwan M, Majumdar CG, Church JC. A Comprehensive Review of Cannabis Potency in the United States in the Last Decade. Biol Psychiatry Cogn Neurosci Neuroimaging. 2021
https://pubmed.ncbi.nlm.nih.gov/33508497/
Quote: “This review examines the concentration of seven major cannabinoids, including Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), in illicit herbal cannabis products seized by the Drug Enforcement Administration (DEA) over the last 10 years in the United States. Cannabis samples received from DEA regional laboratories were analyzed by a validated gas chromatography with flame ionization detection method, and the results are given in the report. A total of 14,234 samples of herbal cannabis have been analyzed over the last 10 years (between January 1, 2009, and December 31, 2019). The number of samples received over the last 5 to 6 years has decreased dramatically owing to the legalization of marijuana for either medical or recreational purposes in many U.S. states. The results showed that the mean Δ9-THC concentration has increased over the last 10 years, from 9.75% in 2009 to 14.88% in 2018 and 13.88% in 2019. The mean Δ9-THC:CBD ratio rose substantially from 24.81 in 2009 to 103.48 in 2017. A decrease in THC:CBD ratio was recorded in the last 2 years, 54.39 in 2018 and 24.58 in 2019, indicating the trend in the production of more high-CBD-containing products. Our results showed an overall increase in potency of illicit cannabis, from approximately 10% in 2009 to approximately 14% in 2019. These results are in agreement with other potency monitoring programs in several European countries. There appears to be a recent trend of the inclusion of higher CBD levels containing chemovars in illicit cannabis.”
#Freeman et al. Changes in delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) concentrations in cannabis over time: systematic review and meta-analysis. 2020.
https://onlinelibrary.wiley.com/doi/10.1111/add.15253
Quote: “Concentrations of delta-9-tetrahydrocannabinol (THC) in international cannabis markets increased from 1970 to 2017 while cannabidiol (CBD) remained stable. Increases in THC were greater in cannabis resin than herbal cannabis. Rising THC in herbal cannabis was attributable to an increased market share of high-THC sinsemilla relative to low-THC traditional herbal cannabis.”
There is regional variation and it could be that in some states it has increased more than the others but the general trend is pretty evident.
#Smart R, Caulkins JP, Kilmer B, Davenport S, Midgette G. Variation in cannabis potency and prices in a newly legal market: evidence from 30 million cannabis sales in Washington state. Addiction. 2017
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673542/
Quote: “Traditional cannabis flowers still account for the majority of spending (66.6%), but the market share of extracts for inhalation increased by 145.8% between October 2014 and September 2016, now composing 21.2% of sales. The average THC-level for cannabis extracts is more than triple that for cannabis flowers (68.7% compared to 20.6%). For flower products, there is a statistically significant relationship between price per gram and both THC [coefficient = 0.012; 95% confidence interval (CI) = 0.011 to 0.013] and CBD [coefficient = 0.017; CI = 0.015 to 0.019]. The estimated discount elasticity is −0.06 [CI = −0.07 to −0.05].”
Quote: “Washington’s legal cannabis market has trended toward higher-THC products, as flower products with THC concentration over 20% and extract products with over 60% THC are now commonplace. By comparison, national estimates of average THC level for cannabis seized during prohibition did not exceed 5% in the US until 2001 [48], and as recently as 2010 typically ranged from 8% to 13% [41, 42]. Potency in Washington State also generally exceeds the 15% limit for cannabis products that has been discussed in the Netherlands [49]. In 2015, the strongest Nederwiet sold in Dutch coffeeshops averaged 17% THC (± 3.4%; [43]).”
#Hall W, Leung J, Carlini BH. How should policymakers regulate the tetrahydrocannabinol content of cannabis products in a legal market? Addiction. 2023
https://pubmed.ncbi.nlm.nih.gov/36662648/
Quote: “Since the sale of cannabis to adults was first legalized in Colorado and Washington State in the United States in 2012 the tetrahydrocannabinol (THC) content of cannabis flower has increased, and so have sales of high-potency cannabis vapes, extracts and concentrates, with THC levels higher than 60% [1-4]. The THC content of cannabis has also increased in Canada since cannabis use was legalized in 2018, and sales of high-potency cannabis products were allowed in October 2019 (with the exception of Quebec [5]).”
#Manthey J, Freeman TP, Kilian C, López-Pelayo H, Rehm J. Public health monitoring of cannabis use in Europe: prevalence of use, cannabis potency, and treatment rates. Lancet Reg Health Eur. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8589728/
Quote: “Median THC concentrations in herbal cannabis were reported by 22 countries. Between 2010 and 2019, THC concentration modestly increased, from 6·9% (Interquartile range (IQR): 4·7 to 9·2%) to 10·6% (IQR: 7·2 to 12·7%; see also Figure 5). Regression analyses suggest that THC concentrations in herbal cannabis did not significantly decline in any country in Europe. However, significantly increasing THC concentrations in herbal cannabis rose were identified in six countries (Portugal, Estonia, Czechia, Poland, Sweden, Hungary) at an annual rate of 0·5 to 1·1 percentage points.”
European Monitoring Centre for Drugs and Drug Addiction (2023), European Drug Report 2023: Trends and Developments, https://www.emcdda.europa.eu/publications/european-drug-report/2023/cannabis_en
Quote: “Data reported to the EMCDDA indicate that the average potency of herbal cannabis in the EU increased by 57 % between 2011 and 2021, while its retail price remained largely stable over the same period. This is despite the slight price increase in 2020 (up 9 % from 2019), likely due to the effects of COVID-19 on the supply of cannabis to some consumer markets (see Figure Indexed trends in price and potency of cannabis resin and herbal cannabis in the EU, 2011-2021) (EMCDDA and Europol, 2020). In 2021, the typical retail price of herbal cannabis in the EU ranged between EUR 8 and EUR 12 per gram, while the typical potency of retail-level herbal cannabis products ranged between 7 % and 13 % (EMCDDA, 2023b).
A marked increase in the potency of cannabis resin was observed between 2011 and 2021, with the average THC content of resin products at the retail level increasing by 191 %. Meanwhile the retail price of resin products has, on average, remained stable during the same 10-year period. This is despite the slight impact on resin prices due to the COVID-19 pandemic (see Figure Indexed trends in price and potency of cannabis resin and herbal cannabis in the EU, 2011-2021) (EMCDDA and Europol, 2020). In 2021, a gram of cannabis resin in the EU typically contained between 12 % and 29 % THC and cost in the range of EUR 6 to EUR 10 (EMCDDA, 2023b).”
https://www.emcdda.europa.eu/publications/eu-drug-markets/cannabis/global-context_en#figure1
Quote: “A trend toward an increase in the potency of cannabis products has been observed in two of the world’s largest consumer markets: the United States, where it quadrupled between 1995 and 2019, and in Europe, where it doubled between 2002 and 2019 (UNODC, 2022) (see Section Cannabis potency: resin increases at much faster pace than herb).”
Freeman TP, Groshkova T, Cunningham A, Sedefov R, Griffiths P, Lynskey MT. Increasing potency and price of cannabis in Europe, 2006-16. Addiction. 2019
https://pubmed.ncbi.nlm.nih.gov/30597667/
Quote: “Resin potency increased from a mean [95% confidence interval (CI)] of 8.14% THC (6.89, 9.49) in 2006 to 17.22 (15.23, 19.25) in 2016. Resin price increased from 8.21 euros/g (7.54, 8.97) to 12.27 (10.62, 14.16). Resin increased in value, from 11.00 mg THC per euro (8.60, 13.62) to 16.39 (13.68, 19.05). Quadratic time trends for resin potency and value indicated minimal change from 2006 to 2011, followed by marked increases from 2011 to 2016. Herbal cannabis potency increased from 5.00% THC (3.91, 6.23) to 10.22 (9.01, 11.47). Herbal price increased from 7.36 euros/g (6.22, 8.53) to 12.22 (10.59, 14.03). The value of herbal cannabis did not change from 12.65 mg of THC per euro (10.18, 15.34) to 12.72 (10.73, 14.73). All price trends persisted after adjusting for inflation.”
Dujourdy L, Besacier F. A study of cannabis potency in France over a 25 years period (1992-2016). Forensic Sci Int. 2017
https://pubmed.ncbi.nlm.nih.gov/28122324/
Quote: “This article exploits the analytical data of cannabis samples analyzed in the five French forensic police laboratories over 25 years. The increase potency of both herbal and resin cannabis in France is proved through the monitoring of THC content. For cannabis resin, it has slowly risen from 1992 to 2009, before a considerable increase in the last four years (mean THC content in mid-2016 is 23% compared to 10% in 2009). For herbal cannabis, it has known three main stages of growth (mean THC content is 13% in 2015 and mid-2016 compared to 7% in 2009 and 2% in 1995). The calculation of THC/CBD ratios in both herbal and resin samples confirms the recent change in chemotypes in favor of high potency categories. Finally, the CBN/THC ratios in marijuana samples were measured in order to evaluate the freshness of French seized hemp.”
Mahamad S, Wadsworth E, Rynard V, Goodman S, Hammond D. Availability, retail price and potency of legal and illegal cannabis in Canada after recreational cannabis legalisation. Drug Alcohol Rev. 2020
https://pubmed.ncbi.nlm.nih.gov/32291811/
Quote: “ In the 2 months post-legalisation in Canada (November-December 2018), legal and illegal cannabis retailers were identified from government lists and online directories. The store location, price and Δ9-tetrahydrocannabinol (THC) and cannabidiol levels of dried herb and cannabis cookies were collected from retailer websites or Weedmaps.
Results: We identified 185 legal retailers (22 online stores, 163 storefronts; 65 government-run stores, 120 private stores) and 944 illegal retailers (791 delivery-only services, 157 storefronts). Relative to legal dried herb, illegal dried herb was lower in price (1 g: $10.23 vs. $11.08, ⅛ oz: $9.37/g vs. $10.88/g, ½ oz: $8.18/g vs. $8.85/g; P < 0.05 for all) and higher in potency (THC: 20.5% vs. 16.1%, cannabidiol: 2.4% vs. 1.7%; P < 0.05 for both). Legal private stores had higher prices for dried herb than government-run stores (1 g: $13.08 vs. $10.89, ⅛ oz: $12.75/g vs. $10.45/g, ½ oz: $10.85/g vs. $8.71/g, 1 oz: $8.54/g vs. $7.22/g; P < 0.05 for all). On average, one cannabis cookie in the illegal market contained 96 mg of THC and cost $1.57 per 10 mg of THC.”
– While ever more potent strains are bred, products like edibles or concentrates with more than 60% THC have become increasingly common. While the share of products with less than 15% THC has declined.
#Smart R, Caulkins JP, Kilmer B, Davenport S, Midgette G. Variation in cannabis potency and prices in a newly legal market: evidence from 30 million cannabis sales in Washington state. Addiction. 2017
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673542/
Quote: “Among flower products, the market share of strains with greater than 15% THC has grown to 92.5% of flower sales (Figure 3), and (not shown) an even greater share of THC consumption. Flowers with less than 10% THC now account for less than 2% of flower expenditures, and market share for flower products with 10–15% THC has significantly declined by 60.4% since October 2014 (linear trend P=0.007; see Table S2). In contrast, the market share of flower products with more than 20% THC has increased by 48.4% since October 2014, now accounting for 56.5% of retail expenditures on cannabis flower; however, this linear trend was not significant (P=0.228).”
#Goodman et al. Prevalence and forms of cannabis use in legal vs. illegal recreational cannabis markets. 2020
Quote: “Consumption of cannabis concentrates, edibles and other product types was also more common in US states with a legal non-medical cannabis market. This is likely due to increased availability of a variety of product types in legal markets, and may be evidence of a transition from dried herb to other, more processed product types (Caulkins et al., 2018; Daniulaityte et al., 2018; Loflin & Earleywine, 2014; Smart, Caulkins, Kilmer, Davenport, & Midgette, 2017). The odds of using high-potency concentrates and cannabis edibles in the past year were 1.4–1.8 times higher in US legal states, after adjustment for socio-demographic factors. More striking differences were found in past 12- month use of vaped oils and cannabis-infused drinks, which were 1.5–2.5 times more prevalent in legal markets. These findings are consistent with data from the first states to legalize non-medical cannabis, which suggest a growing popularity of high-potency extracts and edibles in a legal market. In Washington, wax/shatter/resin/dabs accounted for 55% of the extract market in 2016, and vape cartridges for 34% (Caulkins et al., 2018). The average potency level of these products can be remarkably high: 2016 data from Washington indicated an average potency of 70% THC across extract categories (Caulkins et al., 2018). The increasing popularity of high potency products has been highlighted as a public health concern, although the potential health effects remain unclear (Brown, 2019; 2019; Ontario Public Health, 2019). Finally, the findings also indicate that consumers in legal markets are almost twice as likely to consume cannabis products often classified as ‘medicinal’, such as tinctures and topical ointments. The diversification of cannabis products, and the range of uses for which products are consumed, warrant greater attention in future studies, particularly with respect to understanding the factors that guide product selection for both medical and non-medical use. Indeed, previous research suggests that products such as high-potency concentrates are growing in popularity even among medical users (Loflin & Earleywine, 2014).”
#Hammond et al. Trends in the use of cannabis products in Canada and the USA, 2018 – 2020: Findings from the International Cannabis Policy Study. 2022.
Quote: “Although dried flower continues to be the dominant cannabis product in the US and Canada, the findings indicate a potential shift from dried flower to other forms of cannabis.
The use of dried flower declined between 5 to 8 percentage points over the three-year period of study, in parallel with a rise in the use of processed cannabis products.”
– Unfortunately just about every problem weed creates gets worse at higher THC doses.
– Unfortunately just about every problem weed creates gets worse at higher THC doses.
As summarized in the following paragraph, there are several studies on the increased risks of harm with increased cannabis potency, i.e THC content.
#Hasin DS, Borodovsky J, Shmulewitz D, Walsh C, Livne O, Struble CA, Aharonovich E, Fink DS, Budney A. Use of highly-potent cannabis concentrate products: More common in U.S. states with recreational or medical cannabis laws. Drug Alcohol Depend. 2021 Dec 1;229(Pt B):109159. doi: 10.1016/j.drugalcdep.2021.109159. Epub 2021 Oct 29. PMID: 34844095; PMCID: PMC8667084.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8667084/
Quote: “Cannabis products with higher THC concentrations (i.e., higher-potency products) are associated with greater risk of harms (Brunette et al., 2018; Chiu et al., 2021; Englund et al., 2017; Freeman and Winstock, 2015; Rigucci et al., 2016), including more rapid progression to first symptoms of CUD (Arterberry et al., 2019), CUD severity(Freeman and Winstock, 2015), anxiety disorders(Hines et al., 2020), psychotic disorders(Di Forti et al., 2015), and other cannabis-related problems (e.g., with memory (Freeman and Winstock, 2015; Hines et al., 2020), family or friends(Hines et al., 2020)). Although flower products remain the most commonly used, cannabis concentrates are increasing in popularity (Bidwell et al., 2021; Schaneman, 2021; Spindle et al., 2019). Thus, determining whether state cannabis legalization status is associated with use of cannabis concentrate products, with their high likelihood of having higher THC potency than plant/flower cannabis, is an important element in understanding the public health impact of changing cannabis laws.”
– At the same time more and more people use weed.
– At the same time more and more people use weed.
#UNODC, World Drug Report 2023 (United Nations publication, 2023).
https://www.unodc.org/res/WDR-2023/WDR23_Exsum_fin_SP.pdf
Quote: “Cannabis continues to be the most used drug, with an estimated 219 million users (4.3 per cent of the global adult population) in 2021. Use of the drug is increasing and although globally cannabis users are mostly men (about 70 per cent), the gender divide is reducing in some subregions; women account for 42 per cent of cannabis users in North America.
[...]
In 2021, 5.3 per cent of 15–16-year-olds worldwide (13.5 million individuals) had used cannabis in the past year.”
https://www.unodc.org/res/wdr2021/field/WDR21_Booklet_3.pdf
There is a lot of regional variation on the patterns of use. It increased more in some places whereas in some others didn’t change much. In the following, there are charts showing change of prevalence in the countries and regions sampled from the world drug report.
#Manthey et al. Public health monitoring of cannabis use in Europe: prevalence of use,
cannabis potency, and treatment rates. 2021.
https://www.thelancet.com/action/showPdf?pii=S2666-7762%2821%2900213-1
Quote: “Between 2010 and 2019, past-month prevalence of cannabis use increased by 27% in European adults (from 3.1 to 3.9%), with most pronounced relative increases observed among 35-64 year-olds. In 13 out of 26 countries, over 20% of all past-month users reported high-risk use patterns. The rate of treatment entry for cannabis problems per 100,000 adults increased from 27.0 (95% CI: 17.2 to 36.8) to 35.1 (95% CI: 23.6 to 46.7) and has mostly plateaued since 2015.”
– In the US more people consume cannabis daily than alcohol for the first time in 2022.
#JP Caulkins. Changes in self-reported cannabis use in the United States from 1979 to 2022. 2024.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/add.16519
Quote: “Whereas the 1992 survey recorded 10 times as many daily or near daily alcohol as can-nabis users (8.9 vs. 0.9 M), the 2022 survey, for the first time, recorded more daily andnear daily users of cannabis than alcohol (17.7 vs. 14.7 M). Far more people drink, but high-frequency drinking is less common. In 2022, the median drinker reported drinking on 4–5 days in the past month, versus 15–16 days in the past month for cannabis. In 2022, past-month cannabis consumers were almost four times as likely to report daily or near daily use (42.3% vs. 10.9%) and 7.4 times more likely to report daily use (28.2%vs. 3.8%).”
– In Canada 26% of people 16 and older use it, up from 22% in 2018.
– In Canada 26% of people 16 and older use it, up from 22% in 2018.
The most recent data we could find was 2023 Canadian Cannabis Survey, results of which are summarized in the following page.
#Canadian Cannabis Survey 2023: Summary
Quote: “Starting in 2018, Canadians were asked about their cannabis use within the past 12 months. Twenty-six percent (26%) of people 16 years of age and older reported having used cannabis for non-medical purposes in the past 12 months, unchanged from the previous cycle (27%). Past 12-month cannabis use increased over time from 22% in 2018 (Figure 6). Note that due to the data collection methodology, the CCS may provide general population prevalence estimates for cannabis use that are higher than other Canadian surveys.
As in previous years, past 12-month cannabis use for non-medical purposes was highest among 20 to 24 year olds (48%), unchanged from 2018 and 2022 (Figure 6). This was followed by 16 to 19 year-olds (43%), up from both 2018 and 2022 (36% and 37%, respectively), and those 25 years and older (23%), up from 2018 but down from 2022 (19% and 25%, respectively).”
#Cannabis use (non-medical) in Canada. 2024.
https://health-infobase.canada.ca/cannabis/
Quote: “More than a quarter of Canadians reported cannabis use in the past 12 months
Past 12-month cannabis use in 2023 (26%) increased from 2018 (22%).
Approximately 1 in 6 Canadians reported cannabis use in the past 30 days
Past 30-day cannabis use increased from 15% in 2018 to 17% in 2023, and decreased from 19% in 2022 to 17% in 2023.
In 2023, past 30-day use remained higher among males (19%, unchanged from 19% in 2018) than among females (15%, an increase from 11% in 2018).
In 2023, past 30-day use remained higher among Canadians aged 16-19 years (29%, an increase from 23% in 2018) and 20-24 years (31%, unchanged from 30% in 2018) than among people age 25+ (15%, an increase from 13% in 2018).
Frequency of daily or almost daily cannabis use remained unchanged
Six percent (6%) of all Canadians reported using cannabis daily or almost daily, unchanged from 5% in 2018 and a decrease from 7% in 2022.
This represented 23% of Canadians who reported using cannabis in the past 12 months, unchanged from 25% in both 2018 and 2022.
In 2023, daily/almost daily use remained higher among males (7%, unchanged from 7% in 2018) than among females (5%, an increase from 4% in 2018).
In 2023 daily/almost daily use remained higher among Canadians aged 16-19 years (9%, unchanged from 7% in 2018) and 20-24 years (11%, unchanged from 12% in 2018) than among people age 25+ (5.3%, an increase from 4.6% in 2018).”
#Canadian Cannabis Survey 2023: Summary
https://www.canada.ca/en/health-canada/services/drugs-medication/cannabis/research-data/canadian-cannabis-survey-2023-summary.html
Quote: “Canadians who reported using cannabis for non-medical purposes over the past 12 months were asked how frequently they used it. Over half (57%) reported using cannabis 3 days per month or less, and 15% reported daily cannabis use (Figure 7). Compared to the previous cycle in 2022, more people used cannabis 2 to 3 days per month, while fewer used 3 to 4 days per week or daily. Over the 6-year period, frequency of cannabis use was generally unchanged, with the exception that more people used cannabis 5 to 6 days per week and fewer used daily compared to 2018 (Figure 7).”
However, they also point out that these numbers can be higher than the other reports due to differences in data collection.
#Technical notes for data findings on cannabis use for non-medical purposes among Canadians aged 16+ from 2018 to 2023.
https://health-infobase.canada.ca/cannabis/technical-notes.html
Quote: “Health Canada monitors the prevalence of cannabis use among Canadians using several population surveys, including the Canadian Alcohol and Drugs Survey (CADS), the Canadian Community Health Survey (CCHS), and the Canadian Student Tobacco, Alcohol and Drugs Survey (CSTADS). CADS 2019 indicates that 21% of Canadians age 15 and older (or 6.4 million) had used cannabis in the previous 12 months (22% among age 15 to 19 years; 45% among age 20 to 24 years; and 19% among age 25 years and older). CCHS 2021 similarly indicates that 22% of Canadians aged 15 and older (or 6.8 million) had reported cannabis use in the previous 12 months. CSTADS 2021/22 indicates that 18% of students in grades 7 to 12 (approximately 383,000) had used cannabis in the previous 12 months.”
Another datasource is CADS however the last edition was from 2019, so we used the data from Canadian Cannabis Survey 2023.
#Canadian Alcohol and Drugs Survey (CADS): summary of results for 2019
https://www.canada.ca/en/health-canada/services/canadian-alcohol-drugs-survey/2019-summary.html#a3
Quote: “In 2019, the prevalence of past-year cannabis use (for medical or non-medical purposes) was 21% (6.4 million), an increase compared to 2017 (15% or 4.4 million), and compared to 2015 (12% or 3.6 million). In 2019, past-year cannabis use was more prevalent among males (23% or 3.5 million) than females (19% or 2.9 million), which is consistent with previous cycles. The prevalence of past-year cannabis use among males and females increased from 2017 (19% and 11%, respectively). Table 4 presents past-year cannabis use among Canadians since 2008.”
– It is not possible to say if legalization is the reason for this though, since studies are pretty inconsistent and vary massively between different users. In some consumption went up, in others it stayed stable – and the trend to use more weed began in the early 90s and sped up in the 2000s, way earlier than legalization.
– It is not possible to say if legalization is the reason for this though, since studies are pretty inconsistent and vary massively between different users. In some consumption went up, in others it stayed stable – and the trend to use more weed began in the early 90s and sped up in the 2000s, way earlier than legalization.
In the countries where it is legalized, there is a tendency towards an increase in prevalence. However, this does not mean that legalization is the reason for the prevalence. Legalization might have different effects on different user groups, based on age or use frequency, as well which contributes to the variation and makes it difficult to identify how the correlations work. Also, countries with high prevalence are also the ones that are more likely to legalize or decriminalize cannabis. So there is also a bidirectional relationship.
#Manthey J, Rehm J, Verthein U. Germany's cannabis act: a catalyst for European drug policy reform? Lancet Reg Health Eur. 2024
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11109464/
Quote: “In a systematic review of 164 studies conducted to inform German policy-makers in drafting the Cannabis Act, we assessed the impact of legalising cannabis for recreational purposes.11 Summarising the empirical evidence from Canada, the US states, and Uruguay, we found that cannabis legalisation might serve as a catalyst in accelerating the rising trend in the prevalence of cannabis use. This effect was particularly evident in controlled study designs that involved time periods of at least two years following the law's implementation.12, 13, 14 Parallel to the increase in cannabis use, we also found indications for increases in acute (e.g., intoxications, injuries) and chronic (e.g., cannabis use disorder) health harms attributable to cannabis use linked to the legalisation of cannabis for recreational purposes.15, 16, 17
[...]
Importantly, we need to stress that substance use is not entirely determined by the substance's legal status or even by market factors. Prevalence estimates since 1995 show that cannabis use has gained and lost its appeal over time (first temporary peak in 200329:) without any meaningful changes in the regulation of cannabis during that period. Since 2009, cannabis use has increased not only in Germany, but also in many European countries, including France and the Netherlands.31 Interestingly, the prevalence of cannabis use in France is among the highest in European countries, despite pursuing a very repressive approach involving the charging of large fines.32 In contrast, the Netherlands have pursued a very liberal approach to cannabis for decades but have seen cannabis use prevalence below the French benchmark.31 Overall, it appears that social norms or, more generally, cultural factors, appear to be more important in explaining trends in cannabis use than regulations such as the Cannabis Act.”
In the following, there are some country specific studies for further reading.
#Hall W, Stjepanović D, Dawson D, Leung J. The implementation and public health impacts of cannabis legalization in Canada: a systematic review. Addiction. 2023
https://pubmed.ncbi.nlm.nih.gov/37380613/
Quote: “Legalization of cannabis in Canada appears to have reduced cannabis arrests and increased access to a variety of more potent cannabis products at lower prices. Since 2019, recent cannabis use in Canada has modestly increased among adults but not among adolescents. There is evidence of increased acute adverse effects of cannabis among adults and children.”
#Gunadi C, Zhu B, Shi Y. Recreational cannabis legalization and transitions in cannabis use: findings from a nationally representative longitudinal cohort in the United States. Addiction. 2022
https://pubmed.ncbi.nlm.nih.gov/35618659/
Quote: “Our results suggested associations between RCL and cannabis use transitions if we compared RCL states to states without any type of cannabis legalization. Youths may have a higher odds of transitioning from cannabis nonusers to users if they were exposed to RCL during the transition. This finding was consistent with some repeated cross-sectional studies (5, 8, 11) and small-scale longitudinal cohort studies (14). Adult cannabis nonusers may have higher odds of transitioning to users as well as transitioning to frequent users, corroborating a repeated cross-sectional study on adult population. (11) In addition, adult cannabis users may have a lower odds of transitioning to nonusers. We encourage future research to validate our findings with alternative data sources.”
In order to distinguish the effects of legalization of the frequency of use, researchers compared twins living in legal (Colorado) and illegal (Minnesota) states before and after recreational cannabis legalization in 2014. The study estimated a 20% increase in the frequency of use due to recreational cannabis legalization in legal states.
#Zellers SM, Ross JM, Saunders GRB, Ellingson JM, Anderson JE, Corley RP, Iacono W, Hewitt JK, Hopfer CJ, McGue MK, Vrieze S. Impacts of recreational cannabis legalization on cannabis use: a longitudinal discordant twin study. Addiction. 2023 https://pubmed.ncbi.nlm.nih.gov/36002928/
Quote: “Conclusions: In the United States, there appears to be a ~ 20% average increase in cannabis use frequency attributable to recreational legalization, consistent across increasingly rigorous designs. In addition, the heritability of cannabis use frequency appears to be moderated by legalization.”
Following is a review of 61 studies published from 2016 to 2022 studying the effects of recreational cannabis legalization (RCL) on substance use, health, attitude-related, driving, and crime-related outcomes. Even though there is a lot of regional heterogeneity, they found that literature suggests negative consequences of legalization, but with generally small short-term impact. They point out more well-defined research is needed.
#Farrelly KN, Wardell JD, Marsden E, Scarfe ML, Najdzionek P, Turna J, MacKillop J. The Impact of Recreational Cannabis Legalization on Cannabis Use and Associated Outcomes: A Systematic Review. Subst Abuse. 2023
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10176789/
Quote: “The overall synthesizing of the literature revealed heterogenous and complex effects associated with RCL implementation. The varied findings across behavioral and health related outcomes does not give a clear or categorical answer as to whether RCL is a negative or positive policy change overall. Rather, the review reveals that while a great deal of research is accumulating, there remains a need for more definitive findings on the causal role of RCL on a large variety of substance use, health, attitude-related, driving, and crime-related outcomes.
[...]
Overall, studies examining cannabis use behavior revealed evidence for cannabis use increases following RCL, particularly for young adults (100%), peri-natal users (66%), and certain clinical populations (66%).47,54,59 While general adult samples had some mixed findings, the majority of studies (80%) suggested increasing rates of use associated with RCL. 51
[...]
In contrast to studies of adults, studies of adolescents pointed to inconsistent evidence of RCL’s influence on cannabis use rates,38,45 with 60% of studies finding no change or inconsistent evidence surrounding adolescent use following RCL. Thus, a key conclusion of the cannabis use literature is that there is not overwhelming evidence that RCL is associated with increasing rates of cannabis among adolescents, which is notable as potential increases in adolescent use is a concern often voiced by critics of RCL. 16”
#Compton WM, Han B, Jones CM, Blanco C. Cannabis use disorders among adults in the United States during a time of increasing use of cannabis. Drug Alcohol Depend. 2019
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7028308/
Quote: “According to the NSDUH data, past-year cannabis use, initiation, and use frequency increased among U.S. adults during 2002–2017, consistent with an increasing number of states legalizing medical and nonmedical cannabis use in the U.S. and with a decrease in perceived harmfulness of cannabis use over time (Compton et al., 2016; Hasin, 2018;
ProCon, 2018). Increases persisted during the years 2015 through 2017, confirming and extending findings from our earlier study of 2002–2014 (Compton et al., 2016). Among adults during 2002–2017, the prevalence of cannabis use increased from 10.4% to 15.3%, cannabis initiation increased from 0.7% to 1.4%, and the prevalence of daily or near daily cannabis use more than doubled, increasing from 1.9% to 4.2%.”
There has been an increase in usage in the US and Europe already during the 90s which was associated with the decreased perception of risk from using cannabis.
#World Drug Report 2021 (United Nations publication, Sales No. E.21.XI.8).
#Johnston et al. Monitoring the Future national survey results on drug use, 1975-2015: Overview, key findings on adolescent drug use. 2016. Ann Arbor: Institute for Social Research, The University of Michigan.
#Yu, B., Chen, X., Chen, X. et al. Marijuana legalization and historical trends in marijuana use among US residents aged 12–25: results from the 1979–2016 National Survey on drug use and health. BMC Public Health 20, 156 (2020).
https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-020-8253-4
– A big narrative about weed is that it is not addictive, or at least not that big of a deal. And for most people this is true.
– A big narrative about weed is that it is not addictive, or at least not that big of a deal. And for most people this is true.
#Government of Canada. Addiction to cannabis. 2024.
Quote: “Contrary to popular belief, people can become addicted to cannabis. Continued, frequent and heavy cannabis use can cause physical dependency and addiction.
Some people can develop tolerance to the effects of cannabis. Tolerance is characterized by a need for larger doses of a drug to maintain the same effects. Tolerance can develop after a few doses. In some people, tolerance can eventually lead to physical dependence and/or addiction.
Addiction can develop at any age, but youth are especially vulnerable because their brains are still developing.
Some people are also more prone to becoming addicted than others. It's estimated that 1 in 3 who use cannabis will develop a problem with their use. It's also estimated that 1 in 11 (9%) of those who use cannabis will develop an addiction to it. This statistic rises to about 1 in 6 (17%) for people who started using cannabis as a teenager. If a person smokes cannabis daily, the risk of addiction is 25% to 50%.”
#M. Rotermann. Using the Severity of Dependence Scale to examine cannabis consumers with impaired control in Canada. 2023.
https://www150.statcan.gc.ca/n1/pub/82-003-x/2023006/article/00001-eng.htm
Quote: “More than three-quarters (77.3%, or 4.96 million) of those who reported using cannabis in the past year scored 0 on the SDS, meaning they reported that they would not have any difficulty stopping and never or almost never experienced any of the other four SDS dependency symptoms (Table 1). Those who had total SDS scores from 1 to 3 represented nearly one-fifth (18.1% or 1.2 million) of past-year consumers whereas about 1 in 20 past-year consumers (4.7% or 299,543) scored 4 or more, indicating impaired control (Table 1 and Table 3).
The most frequently experienced SDS item was about how difficult it would be to stop or go without cannabis, with 12.6% of past-year consumers reporting it would be quite difficult, very difficult or impossible (Table 2).”
– Studies clearly show that the majority handle it well – For 8 out of 10 using weed, it is just a casual high and not problematic at all. About 2 in 10 users develop a cannabis use disorder, or CUD. CUD has 11 different symptoms, from the inability to stop when you have had enough, to using it when you know it will have negative consequences, to tolerance and withdrawal. They can all basically reduce to: You are doing it too often, even if it's bad for you and it is less fun than it could be.
– Studies clearly show that the majority handle it well – For 8 out of 10 using weed, it is just a casual high and not problematic at all. About 2 in 10 users develop a cannabis use disorder, or CUD. CUD has 11 different symptoms, from the inability to stop when you have had enough, to using it when you know it will have negative consequences, to tolerance and withdrawal. They can all basically reduce to: You are doing it too often, even if it's bad for you and it is less fun than it could be.
Cannabis Use Disorder is roughly defined as the inability to stop consuming cannabis even when it is causing harm to the user and it is a mental health condition characterized by problematic cannabis use. The diagnostic criteria for CUD has been updated in 2013 from DSM-IV to the DSM-5. Partly due to this distinction, there are multiple numbers for the prevalence of CUD, dependence and addiction in the literature. However, it is generally accepted that 10 to 30% of users get CUD. This ratio is higher in more frequent or long-term users and in different cohorts it can go up to more than 40%. We went with an average value of 20% based on one of the most recent meta-analysis papers that is cited below.
In the DSM-IV, CUD was divided into two separate disorders: cannabis dependence and cannabis abuse. Cannabis dependence was defined by the presence of at least three out of seven criteria, such as tolerance, withdrawal, and continued use despite problems. Cannabis abuse was a less severe disorder characterized by recurrent cannabis use in hazardous situations or legal problems related to cannabis use. The DSM-5 combined the criteria for cannabis abuse and dependence into a single disorder under CUD. The DSM-5 criteria for CUD include 11 symptoms, such as using cannabis in larger amounts or for longer than intended, unsuccessful efforts to cut down or control use, and continued use despite social or interpersonal problems caused by cannabis. The severity of CUD is specified as mild (2-3 symptoms), moderate (4-5 symptoms), or severe (6 or more symptoms)
#Connor JP, Stjepanović D, Budney AJ, Le Foll B, Hall WD. Clinical management of cannabis withdrawal. Addiction. 2022
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9110555
Quote: “CUD is characterized by persistent cannabis use despite negative effects on the social functioning and physical or mental health of the user or the health of other individuals. Two diagnostic systems classify and define the severity of the disorder: the Diagnostic and Statistical Manual of Mental Disorders (DSM)‐5 [1] and International Classification of Diseases (ICD)‐11 [9]. CUD severity is coded in DSM‐5 as mild (presence of two to three symptoms), moderate (presence of four to five symptoms) or severe (presence of six or more symptoms). ICD‐11 classifies cannabis use into hazardous cannabis use (potential to cause harm), harmful pattern of cannabis use (causing harm) and cannabis dependence.”
#Patel J, Marwaha R. Cannabis Use Disorder. 2024
https://www.ncbi.nlm.nih.gov/books/NBK538131/
Quote: “The Diagnostic and Statistical Manual of Mental Disorders, DSM–5, defines cannabis use disorder as the presence of clinically significant impairment or distress in 12 months, manifested by at least 2 of the following:
Cannabis is taken in larger amounts or used over a longer period than intended
Persistent desire to cut down with unsuccessful attempts
Excessive time spent acquiring cannabis, using cannabis, or recovering from its effects
Cravings for cannabis use
Recurrent use resulting in neglect of social obligations
Continued use despite social or interpersonal problems
Important social, occupational, or recreational activities foregone to be able to use cannabis
Continued use despite physical harm
Continued use despite physical or psychological problems associated with cannabis use
Tolerance
Withdrawal symptoms when not using cannabis [4]”
The following meta-analysis study suggests that 1 in 5 people who have ever used cannabis develop CUD whereas 1 in 3 of the regular users -at least weekly- is at the risk of developing CUD.
#J. Leung, G.C.K. Chan, L. Hides, W.D. Hall, What is the prevalence and risk of cannabis use disorders among people who use cannabis? A systematic review and meta-analysis. Addictive Behaviors. 2020.
https://pubmed.ncbi.nlm.nih.gov/32485547/
Quote: “From 1383 records identified, 21 studies were included. Meta-analyses showed that among people who used cannabis, 22% (18-26%) have CUD, 13% (8-18%) have CA, and 13% (10-15%) have CD. Estimates from cohort studies, showed that the risk of developing CD increased to 33% (22-44%) among young people who engaged in regular (weekly or daily) use of cannabis. There was a lack of data from cohort studies to estimate the risk of CUD or CA among regular cannabis users.”
#Lapham GT, Matson TE, Bobb JF, et al. Prevalence of Cannabis Use Disorder and Reasons for Use Among Adults in a US State Where Recreational Cannabis Use Is Legal. JAMA Netw Open. 2023;6(8):e2328934.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2808874
Quote: “In this cross-sectional study of primary care patients in a state with legal recreational cannabis use, CUD was common among patients who used cannabis, with 21% having CUD and 6% having moderate to severe CUD. Patients who used cannabis for medical reasons only were mostly older and likely to use applied products. Patients who reported any nonmedical use were at greatest risk of moderate to severe CUD (7.2% to 7.5%). While the prevalence of moderate to severe CUD was lowest among patients who reported medical use only (1.3%), 13.4% met criteria for mild, moderate, or severe CUD.”
#Mills et al. Prevalence and correlates of cannabis use disorder among Australians using cannabis products to treat a medical condition. 2022.
https://onlinelibrary.wiley.com/doi/full/10.1111/dar.13444
Quote: “A total of 905 participants were included in the analysis. The majority (98%) used illicit cannabis products. Criteria for any-CUD criteria were met by 290 (32.0%), and 117 (12.9%) met criteria for moderate–severe-CUD. Tolerance (21%) and withdrawal (35%) were the most commonly met criteria. Correlates with the strongest association with CUD were inhaled route of administration [odds ratio (OR) = 2.96, 95% credible interval 1.11, 7.06], frequency of cannabis use (OR = 1.24, 1.11–1.35), proportion of cannabis for medical reasons (OR = 0.83, 0.74, 0.94), frequency of tobacco use (OR = 1.10, 1.03, 1.17), age (OR = 0.75, 0.64, 0.90) and pain as main clinical indication (OR = 0.58, 0.36, 1.00).”
#Millar SR, Mongan D, O'Dwyer C, Long J, Smyth BP, Perry IJ, Galvin B. Correlates of patterns of cannabis use, abuse and dependence: evidence from two national surveys in Ireland. Eur J Public Health. 2021
https://pubmed.ncbi.nlm.nih.gov/33624789/
Quote: “Methods: We analyzed data from Ireland's 2010-11 and 2014-15 National Drug Prevalence Surveys, which recruited 5134 and 7005 individuals respectively, aged 15 years or more, living in private households. Multinomial logistic regression was used to identify factors associated with recent (last year) and current (last month) cannabis use compared to experiential use. Binary logistic regression was used to determine factors related to CUD among current users.
Results: The weighted prevalence of experiential cannabis use was 18.3%, with 3.0% and 3.3% of participants indicating recent or current use, respectively; 41.3% of current users indicated having a CUD. Factors associated with both recent or current cannabis use included younger age, not being married or cohabiting, having no dependent children and current use of tobacco or alcohol. Male gender, younger age and lower educational levels were significantly related to CUD among current users.
Conclusions: Males, adolescents/young adults and individuals with lower educational levels are more likely to be current users of cannabis and are at a greater risk of having a CUD. Health professionals should be aware of these factors to improve detection and prevention of CUD.”
#Marel et al. Conditional probabilities of substance use disorders and associated risk factors: Progression from first use to use disorder on alcohol, cannabis, stimulants, sedatives and opioids. Drug and Alcohol Dependence. 2019.
https://www.sciencedirect.com/science/article/pii/S0376871618305313
Quote: “Data were collected as part of the 2007 Australian National Survey of Mental Health and Wellbeing, a nationally representative survey of 8841 Australian adults.
[....] Lifetime cumulative probability estimates indicated that 50.4% of stimulant, 46.6% of opioid, 39% of sedative, 37.5% of alcohol, and 34.1% of cannabis users would develop a SUD on those substances, within an estimated 14, 12, 8, 30, and 23 years after onset respectively. Pre-existing mental disorders were significantly associated with increased risk of developing a SUD for alcohol, cannabis and stimulant use disorder.”
–There are three major risk factors here: The amount of THC, how often you consume and your age when you start using cannabis. The more THC, the more often and the younger you are when you start, the higher your risk. If you smoke too much weed, too often, it will have negative impacts on your life. So if this is you, toning it down a bit will make a big difference.
–There are three major risk factors here: The amount of THC, how often you consume and your age when you start using cannabis. The more THC, the more often and the younger you are when you start, the higher your risk. If you smoke too much weed, too often, it will have negative impacts on your life. So if this is you, toning it down a bit will make a big difference.
Age of onset is a very strong predictor of CUD. It is consistently shown in multiple studies that the earlier one starts consuming cannabis, the higher the likelihood of developing CUD.
The following study for example an early age at onset of cannabis use was found to be associated with more than a two-fold increase in the risk of transition to CUD. Cannabis users who initiated cannabis use prior to 15 years of age had nearly 50% lifetime risk of transitioning to CUD.
#Feingold D, Livne O, Rehm J, Lev-Ran S. Probability and correlates of transition from cannabis use to DSM-5 cannabis use disorder: Results from a large-scale nationally representative study. Drug Alcohol Rev. 2020
https://pubmed.ncbi.nlm.nih.gov/31916333/
Quote: “In our study, an early age at onset of cannabis use was associated with more than a two-fold increase in the risk of transition to CUD; cannabis users who initiated cannabis use prior to 15 years of age demonstrated nearly 50% lifetime risk of transitioning to CUD.”
#Butterworth P, Slade T, Degenhardt L. Factors associated with the timing and onset of cannabis use and cannabis use disorder: results from the 2007 Australian National Survey of Mental Health and Well-Being. Drug Alcohol Rev. 2014
https://pubmed.ncbi.nlm.nih.gov/25186194/
Quote: “The oldest cohort (born 1942–1951) had lower cannabis use than younger cohorts, with first use also occurring at an older age. Multivariable discrete-time survival models showed other substance use, tobacco and alcohol use at very young ages, and mental disorders were associated with increased risk of cannabis use. There were 7.5% of those <65 years old at interview who had a lifetime CUD; mean time from first use to the onset of CUD was 3.3 years, with 90% of cases within eight years. Younger age of initiation and other substance use were strong predictors of the transition from use to CUD. Women with depression were more likely to develop a CUD; social phobia and panic disorder were also associated with transition from cannabis use to CUD.”
#Le Strat Y, Dubertret C, Le Foll B. Impact of age at onset of cannabis use on cannabis dependence and driving under the influence in the United States. Accid Anal Prev. 2015
https://pubmed.ncbi.nlm.nih.gov/25543035/
Quote: “Results: Of the 8068 participants included, 5.15% reported having driven under the influence of cannabis. Among those, only a minority (14.46%) were diagnosed with cannabis dependence. Compared to those who start using cannabis at age 21 years or after, participants who used cannabis before the age of 14 years were 4 times more likely to have a history of cannabis dependence and 3 times more likely to reported having driven under the influence of cannabis. An inverse relationship between the age at onset of cannabis use and driving under the influence and risk of cannabis dependence was found.”
Amount of THC is also a strong predictor of the likelihood to transition to CUD.
#Petrilli, K, Ofori, S, Hines, L, Taylor, G, Adams, S & Freeman, TP. Association of cannabis potency with mental ill health and addiction: a systematic review', The Lancet Psychiatry, 2022.
Quote: “We searched Embase, PsycINFO, and MEDLINE (inception to 14/01/21). Inclusion criteria were observational studies of human participants comparing the association of higher potency cannabis (products with higher concentration of THC) and lower potency cannabis (products with lower concentration of THC), as defined by the studies included, with depression, anxiety, psychosis, or cannabis use disorder (CUD). Of 4,171 articles screened, 20 met eligibility criteria: psychosis (n=8), anxiety (n=8), depression (n=7), CUD (n=6). Overall, use of higher potency cannabis, relative to lower potency cannabis, was associated with increased risk of psychosis and CUD. Evidence was mixed for depression and anxiety.”
#Connor JP, Stjepanović D, Le Foll B, Hoch E, Budney AJ, Hall WD. Cannabis use and cannabis use disorder. Nat Rev Dis Primers. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8655458/
Quote: “The risk of progression from cannabis use to CUD increases with frequency of use. In the USA, adults with CUD, on average, use cannabis 6.2 out of 10 days over a year44. Approximately 17.0% of weekly and 19.0% of daily cannabis smokers met the criteria for cannabis dependence45. In addition, in a longitudinal study almost 1 in 19 (9.7%) non-dependent weekly cannabis users progressed to dependence within a year45. The co-use of tobacco and cannabis is associated with a higher risk of CUD, greater number of withdrawal symptoms and lower rates of cessation than those who use cannabis without tobacco46.”
Though there are also other factors like personal traits or mental health disorders. These could also have an influence on the use patterns. For example, depression might lead to more frequent use which in turn might lead to addiction.
#Rajapaksha et al. A preliminary risk prediction model for cannabis use disorder. Preventive Medicine Reports. 2020.
https://www.sciencedirect.com/science/article/pii/S2211335520301868
Quote: “Several risk factors have been reported for substance use disorders in general and specifically for CUD. These include male sex, early exposure to traumatic events, early use initiation, family history of substance use, childhood depression, and conduct disorder symptoms (Gray and Squeglia, 2018; Meier et al., 2016; Tomko et al., 2019). High impulsivity and certain personality traits are also associated with the disorders (Beaton et al., 2014; Ketcherside et al., 2016). In particular, work by coauthor Filbey’s lab showed that openness distinguishes cannabis-only users from nicotine-only users, co-morbid marijuana and nicotine users, and non-users (Ketcherside et al., 2016). The results from this study also indicate that conscientiousness is lower among cannabis users.”
– 1 in 10 users develop a serious addiction.
– 1 in 10 users develop a serious addiction.
Due to the update from DSM-4 to DSM-5, there are various numbers reported for severe CUD. Some researchers suggest that CD in DSM-IV can correspond to severe CUD, however there is a long time interval between the cohort data used in studies using one measurement so it is difficult to compare.
The following meta-analysis for example reports that 13% of people who used cannabis have CD. And among young people this increases to 33%. These types of studies combine results from multiple studies and therefore have higher statistical power.
#J. Leung, G.C.K. Chan, L. Hides, W.D. Hall, What is the prevalence and risk of cannabis use disorders among people who use cannabis? A systematic review and meta-analysis. Addictive Behaviors. 2020.
https://pubmed.ncbi.nlm.nih.gov/32485547/
Quote: “From 1383 records identified, 21 studies were included. Meta-analyses showed that among people who used cannabis, 22% (18-26%) have CUD, 13% (8-18%) have CA, and 13% (10-15%) have CD. Estimates from cohort studies showed that the risk of developing CD increased to 33% (22-44%) among young people who engaged in regular (weekly or daily) use of cannabis. There was a lack of data from cohort studies to estimate the risk of CUD or CA among regular cannabis users.”
Individual studies on the other hand can report much lower numbers, depending on the demographics and period. Following study conducted in the USA between 2002-2017 for example reports 1.3% of severe CUD among adult users. Interestingly, the study reports increases in the prevalence of two CUD criteria, tolerance and spending a lot of time getting/using cannabis or getting over cannabis effects,
#Compton WM, Han B, Jones CM, Blanco C. Cannabis use disorders among adults in the United States during a time of increasing use of cannabis. Drug Alcohol Depend. 2019
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7028308/
Quote: “Among adult cannabis users, the prevalence of meeting an approximate-DSM-5 CUD diagnosis decreased from 20.1% in 2002 to 16.8% in 2017. Moreover, between 2002 and 2017, the prevalence of mild CUD among adult users remained unchanged around 12.4–13.3%. However, during this time period, the prevalence of moderate and severe CUD
among adult cannabis users decreased from 4.3% to 3.1% and from 2.4% to 1.3%, respectively. The mean number of DSM-5 criteria endorsed by adult users decreased from 0.83 to 0.66. Among adult daily or near daily cannabis users, the prevalence of mild, moderate, and severe CUD all decreased during 2002–2017.”
[...]
“Examining trends in individual CUD criteria during 2002–2017 among adults overall revealed increases in two criteria (tolerance; spending a lot of time getting/using cannabis or getting over cannabis effects) and decreases/no changes in other criteria; among adult cannabis users, there was no change in one criterion (tolerance) and decreases in other criteria.”
In the following large survey in the US for example 1 in 3 of people with lifetime CUD matched the criteria of a severe CUD. However, 1 in 5 people with CUD in the past-year had a severe version. The prevalence of use and patterns of use were not reported in the study so it is difficult to make direct comparisons with the other studies.
#Hasin DS et al. Prevalence and Correlates of DSM-5 Cannabis Use Disorder, 2012-2013: Findings from the National Epidemiologic Survey on Alcohol and Related Conditions-III. Am J Psychiatry. 2016
https://pubmed.ncbi.nlm.nih.gov/26940807/
Quote: “Table 1 shows the prevalences and standard error of 12-month and lifetimeDSM-5 cannabis use disorder for the entire sample and by socio demographic characteristics. In addition, Figure 1 summarizes 12-month prevalence for the entire sample and by sex and age. As shown in Table 1, the prevalences of 12-month and lifetime DSM-5 cannabis use disorder were 2.54% and 6.27%, respectively.The 12-month and lifetime prevalences of mild, moderate, and severe cannabis use disorder were 1.38%, 0.59%,and 0.57% and 2.85%, 1.42%,and 2.00%, respectively.”
In another study, among the past year cannabis users 27% had cannabis abuse and 8% had cannabis dependence based on the DSM-4 criteria, which is generally considered to be corresponding to the moderate to severe CUD in DSM-5.
#Moss HB, Chen CM, Yi HY. Measures of substance consumption among substance users, DSM-IV abusers, and those with DSM-IV dependence disorders in a nationally representative sample. J Stud Alcohol Drugs. 2012
There is also the estimate reported in the following study, however how the number is estimated is not explained.
#Brezing CA, Levin FR. The Current State of Pharmacological Treatments for Cannabis Use Disorder and Withdrawal. Neuropsychopharmacology. 2018
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5719115/
Quote: “It is estimated that anywhere from 8 to 12% of regular cannabis users will develop moderate-severe cannabis use disorder (CUD) over time (Moss et al, 2012; Perkonigg et al, 2008).“
– They usually consume daily and their life is significantly impaired or held back – because they spend a lot of their time either using or recovering from cannabis use. Since their brain is building a tolerance they need increasingly high doses or stronger weed, often both.
Following study reported that among the past year users, ones with cannabis dependence on average used cannabis 232 days per year and had 4 joints per day.
#Moss HB, Chen CM, Yi HY. Measures of substance consumption among substance users, DSM-IV abusers, and those with DSM-IV dependence disorders in a nationally representative sample. J Stud Alcohol Drugs. 2012
Spending a lot of time and tolerance were also found to be the two most prevalent symptoms in the following study. Tolerance can be a bit tricky though since many chronic users don't necessarily increase use, nevertheless individuals who develop CUD do tend to increase use and develop tolerance.
#Compton WM, Han B, Jones CM, Blanco C. Cannabis use disorders among adults in the United States during a time of increasing use of cannabis. Drug Alcohol Depend. 2019
The study below followed up the cannabis use and associated risk factors in a group of 14-24 years old users in Germany, two times (4 years and 10 years later) after baseline measurements. The following chart depicts the associations between cannabis abuse and dependence and the symptoms.
#Perkonigg A, Goodwin RD, Fiedler A, Behrendt S, Beesdo K, Lieb R, Wittchen HU. The natural course of cannabis use, abuse and dependence during the first decades of life. Addiction. 2008
– Studies found a variety of negative effects: Heavy users can experience bad moods, feel irritable, restless, paranoid, anxious and even depressive. In a sad twist of irony, for many addicts it feels like they need weed to fight these withdrawal symptoms – maybe it did even help at first – while in reality, it makes those symptoms stronger and more persistent.
– Studies found a variety of negative effects: Heavy users can experience bad moods, feel irritable, restless, paranoid, anxious and even depressive. In a sad twist of irony, for many addicts it feels like they need weed to fight these withdrawal symptoms – maybe it did even help at first – while in reality, it makes those symptoms stronger and more persistent.
These are also the withdrawal symptoms which lead users to “self-medicate” and continue to use cannabis, but this in turn will make the dependence stronger.
#Wallis et al. "Predicting Self-Medication with Cannabis in Young Adults with Hazardous Cannabis Use" International Journal of Environmental Research and Public Health. 2022.
https://www.mdpi.com/1660-4601/19/3/1850
Quote: “Questions were written for this study and designed to probe specific psychiatric and somatic reasons cited in the self-medication and CWS literature to assess self-medication. Seven of the most commonly cited reasons for self-medication were selected: depression and mood [39]; feelings of isolation and loneliness [52]; anxiety and social anxiety [53,54]; sleep [40]; concentration [18]; and pain [41]. Participants were first asked, “Do you use marijuana to help any problems such as depression, anxiety, sleep problems, social stress, pain, or other issues?” The response options were “Yes”, coded as 1, and “No”, coded as 0. The endorsement of any self-medication is used as our dependent variable in the model.”
Effects are not limited to these but we can not cover it all within the span of a video. But in the following, we added a few studies for further reading.
In the following review, the authors gathered the existing evidence on the effect of cannabis and identified studies finding impact or no impact on several behavioral outcomes. Their findings showed that psychosis and psychosocial functioning are the two most strongly evidenced outcomes.
#Sorkhou et al. The Behavioral Sequelae of Cannabis Use in Healthy People: A Systematic Review. 2021.
https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.630247/full
Quote: “Our search detected a total of 2,870 studies, from which we extracted 124 relevant studies from the literature on cannabis effects in the non-clinical population. Effects of cannabis on several behavioral sequelae including cognition, motivation, impulsivity, mood, anxiety, psychosis intelligence, and psychosocial functioning were identified. The preponderance of the evidence suggests that frequency of cannabis use, THC (but not CBD) content, age of onset, and cumulative cannabis exposure can all contribute to these adverse outcomes in individuals without a pre-existing medical condition or psychiatric disorder. The strongest evidence for the negative effects of cannabis are for psychosis and psychosocial functioning.”
Studies suggested a multitude of behavioral changes upon frequent cannabis use from deficits in inhibitory control to negative effects on interpersonal interactions and increased perception of hostility.
#Ansell EB, Laws HB, Roche MJ, Sinha R. Effects of marijuana use on impulsivity and hostility in daily life. Drug Alcohol Depend. 2015
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4330120/
Quote: “Marijuana use was associated with increased impulsivity on the same day and the following day relative to days when marijuana was not used, independent of alcohol use. Marijuana was also associated with increased hostile behaviors and perceptions of hostility in others on the same day when compared to days when marijuana was not used. These effects were independent of frequency of marijuana use or alcohol use. There were no significant effects of alcohol consumption on impulsivity or interpersonal hostility.”
#Kesner AJ, Lovinger DM. Cannabis use, abuse, and withdrawal: Cannabinergic mechanisms, clinical, and preclinical findings. J Neurochem. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9291571
Quote: “The DSM‐5 defines cannabis withdrawal as experiencing at least three of the following symptoms upon cessation of regular cannabis use: (1) Irritability/aggression, (2) nervousness/anxiety, (3) disrupted sleep, (4) hypophagia and weight loss, (5) restlessness, (6) depressed mood, (7) somatic symptoms causing discomfort, for example, abdominal pain, shakes, sweating, fever/chills, and headache (American Psychiatric Association, 2013). Other cannabis withdrawal symptoms have also been reported including vivid unpleasant dreams or nightmares (Budney et al., 2003), feeling tense or unable to achieve goals (Bahji et al., 2020), changes in libido, boredom, and craving cannabis (Copersino et al., 2006). Increased appetite and weight gain have also been observed in individuals abstaining from cannabis, but this is typically reported later in withdrawal (Copersino et al., 2006; Levin et al., 2010), and could potentially be a post‐withdrawal symptom (Boggs et al., 2013).”
#Wallis, Dorothy et al. Predicting Self-Medication with Cannabis in Young Adults with Hazardous Cannabis Use. International Journal of Environmental Research and Public Health. 2022.
https://www.mdpi.com/1660-4601/19/3/1850
Quote: “Using cannabis to reduce psychological and physical distress, referred to as self-medication, is a significant risk factor for cannabis use disorder. To better understand this high-risk behavior, a sample of 290 young adults (ages 18–25; 45.6% female) were recruited from two U.S. universities in January and February of 2020 to complete a survey about their cannabis use and self-medication. Results: seventy-six percent endorsed using cannabis to reduce problems such as anxiety, sleep, depression, pain, loneliness, social discomfort, and concentration. When predicting reasons for self-medication with cannabis, logistic regression models showed that lower CUDIT-R scores, experiencing withdrawal, living in a state where cannabis was illegal, and being female were all associated with higher rates of self-medication. Withdrawal symptoms were tested to predict self-medication with cannabis, and only insomnia and loss of appetite were significant predictors. To further explore why young adults self-medicate, each of the original predictors were regressed on seven specified reasons for self-medication. Young adults experiencing withdrawal were more likely to self-medicate for pain. Participants living where cannabis is legal were less likely to self-medicate for anxiety and depression. Living where cannabis is illegal also significantly predicted self-medicating for social discomfort—though the overall model predicting social discomfort was statistically non-significant. Finally, female participants were more likely to self-medicate for anxiety. These results suggest widespread self-medication among young adults with likely CUD and underscore the complexity of their cannabis use. The findings have implications for understanding why young adults use cannabis in relation to psychological and physical distress and for accurately treating young adults with cannabis use disorder.”
#Kesner AJ, Lovinger DM. Cannabis use, abuse, and withdrawal: Cannabinergic mechanisms, clinical, and preclinical findings. J Neurochem. 2021
– Studies also found that loneliness and frequent cannabis use go hand in hand. If you feel lonely you are more likely to use weed and if you use weed you may experience more loneliness. It is not always easy to say which came first, but they seem to reinforce each other.
– Studies also found that loneliness and frequent cannabis use go hand in hand. If you feel lonely you are more likely to use weed and if you use weed you may experience more loneliness. It is not always easy to say which came first, but they seem to reinforce each other.
Loneliness is one of the commonly stated reasons to self-medicate with cannabis among young people.
#Wallis et al. "Predicting Self-Medication with Cannabis in Young Adults with Hazardous Cannabis Use" International Journal of Environmental Research and Public Health. 2022.
https://www.mdpi.com/1660-4601/19/3/1850
Quote: “Questions were written for this study and designed to probe specific psychiatric and somatic reasons cited in the self-medication and CWS literature to assess self-medication. Seven of the most commonly cited reasons for self-medication were selected: depression and mood [39]; feelings of isolation and loneliness [52]; anxiety and social anxiety [53,54]; sleep [40]; concentration [18]; and pain [41]. Participants were first asked, “Do you use marijuana to help any problems such as depression, anxiety, sleep problems, social stress, pain, or other issues?” The response options were “Yes”, coded as 1, and “No”, coded as 0. The endorsement of any self-medication is used as our dependent variable in the model.”
Another study showed that users with cannabis abuse and dependency have lower levels of perceived social support. It also reported that the most significant predictor of psychological distress among heavy users are negative social interactions whereas reassurance of worth, attachment, and social integration are protective factors against cannabis dependence and abuse.
#Gulliver, T.L., Fowler, K. Exploring Social Context and Psychological Distress in Adult Canadians with Cannabis Use Disorder: To What Extent Do Social Isolation and Negative Relationships Predict Mental Health?. Psychiatr Q 93, 311–323 (2022).
https://doi.org/10.1007/s11126-021-09950-7
Quote: “One of the goals of this study was to identify whether Canadians with lifetime cannabis abuse or dependence (ADC) differ in terms of their perceived social support from what would be expected within the general Canadian adult population. Results indicated that Canadians with ADC perceive significantly lower levels of social support than the overall Canadian sample, an observation consistent with previous research that found cannabis use disorder (CUD) to be associated with lower levels of perceived social support [18] and reduced social network size and diversity [8]. Adults with ADC also scored significantly lower in specific social support subtypes, including attachment (i.e., they were less likely to feel they had someone they were close with), guidance (i.e., they were less likely to feel they had someone to help with making decisions and provide advice), reliable alliance (i.e., they were less likely to feel that others can be counted on in times of stress), social integration (i.e., they were less likely to feel a sense of belonging to a group), and reassurance of worth (i.e., they were less likely to feel recognized by others for their competence). Adults with ADC were also significantly more likely to experience negative social interactions than the general Canadian adult sample, suggesting that individuals with ADC experience fewer and lower quality social interactions than the general population.”
The relation between loneliness and cannabis use is complicated though and it is difficult to determine the directionality of it. Generally for younger users having friends using cannabis is a common reason to start, to fit in a friends group, and being vulnerable to peer pressure. So it might start as a social activity for many early age users. However, there are some risk factors which make maturing out of the habit less likely. A longitudinal study which followed up a group of young people (14-24 year olds) suggested that peer use, antisocial personality disorder and ability to cope with several problems, including problems with friends, were risk factors for continued use of cannabis.
#Perkonigg A, Goodwin RD, Fiedler A, Behrendt S, Beesdo K, Lieb R, Wittchen HU. The natural course of cannabis use, abuse and dependence during the first decades of life. Addiction. 2008
https://pubmed.ncbi.nlm.nih.gov/18269364/
Quote: “At 4-year follow-up, having had more than one drug-using peer (OR = 1.8, 95% CI = 1.1–2.7) at baseline and antisocial personality disorder (ASPD) (OR = 2.5, 95% CI = 1.4– 4.4) were the strongest predictors and correlate, following younger age and higher frequency of use or abuse and dependence. In addition, early onset of cannabis use (OR = 1.3, 95% CI = 1.1–3.6) and low self-competence (OR = 1.7, 95% CI = 1.1–2.6) at baseline predicted use at follow-up. In contrast to outcomes at 4-year follow-up, the risk of use at 10-year follow-up was elevated for those meeting criteria for alcohol dependence at baseline (OR = 2.5, 95% CI = 1.3–4.8), whereas the other associations retained their significance, at least in the crude models (i.e. peer use, ASPD, gender, younger cohort).”
In the following study, 5987 Swiss men assessed longitudinally at the mean ages of 20, 21.5 and 25 years. Their findings suggested that use frequency, CUD severity, major depression severity, ADHD severity, antisocial personality disorder severity and peers with drug problems were associated significantly with higher odds of persistent severe CUD vs. the decreasing trajectory, respectively lower odds for better relationship with parents (before the age of 18) and sociability.
#Marmet S, Studer J, Wicki M, Gmel G. Cannabis use disorder trajectories and their prospective predictors in a large population-based sample of young Swiss men. Addiction. 2021
https://pubmed.ncbi.nlm.nih.gov/32621560/
Quote: “We identified four CUDS trajectories, of which the largest one (88.2%) showed stable low CUDS in each wave. Consistent with the maturing-out hypothesis, the decreasing trajectory (5.2%) was more frequent than the stable-high trajectory (2.6%). The increasing trajectory, with 4.0% of users, was surprisingly large, highlighting the importance of considering trajectories other than maturing-out and persistence. Mental health, substance use, family, peer and personality factors measured at age 20 were associated with membership in the decreasing, stable-high and, to a lesser degree, increasing CUDS trajectories. This underlines the long-term importance of these factors to CUD, and they could be interesting targets for prevention measures, not only for early high CUDS but also its persistence and later increase. CU, CUDS, mental health problems severities, relationship with parents (before the age of 18), peers with drug problems, and the personality dimensions neuroticism-anxiety and sociability at or before age 20 were also associated with persistent CUD. However, these factors were relatively few, effect sizes were small and predictors were mainly associated with persistence via higher CUDS at age 20. It would therefore appear that targeting factors associated with early high CUDS may be more promising for the prevention of persistent CUD, and its long-term consequences, than identifying and targeting factors specifically associated with persistent CUD itself.”
Some users also use cannabis to self-treat loneliness, however solitary cannabis use is associated with greater negative consequences. And the more the addiction etches in, the more intense the behavioral outcomes will be. Since psychosocial functioning is among the very commonly stated negative outcomes, increased use is likely to induce problems in social interactions, which might have restrictive effects in social engagement.
#Okey SA, Waddell JT, Corbin WR. I Smoke Alone: Indirect Effects of Solitary Cannabis Use on Negative Consequences Through Coping Motives. J Stud Alcohol Drugs. 2022
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10768480/
Quote: “Consistent with the social learning framework, this study found that the hypothesized model of context predicting consequences through motives provided a good fit to the data. Results showed that solitary cannabis use directly predicted greater global negative consequences, lack of self-care, academic/occupational problems, impaired control, and physiological dependence symptoms. Solitary use also predicted greater coping, enhancement, and expansion motives, as well as lower conformity motives. As hypothesized, solitary cannabis use was indirectly associated with greater negative consequences via coping motives. These findings are consistent with past cannabis research (Bresin & Mekawi, 2019; Buckner et al., 2007; Spinella et al., 2019; Spradlin & Cuttler, 2019), as well as with the general substance use literature on solitary use, coping motives, and later substance use problems (Corbin et al., 2020; Creswell et al., 2014; Skrzynski & Creswell, 2020; Waddell et al., 2021a).”
In the following study of young adults, those using marijuana more frequently over the past month showed worse social and emotional well-being compared to non-users. Findings suggest that young adult marijuana users, especially daily users, may show poor emotional and social well-being, including more loneliness, more psychological distress, and less flourishing.
#Rhew IC, Cadigan JM, Lee CM. Marijuana, but not alcohol, use frequency associated with greater loneliness, psychological distress, and less flourishing among young adults. Drug Alcohol Depend. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7792981/
Quote: “Greater frequency of marijuana use was associated with higher levels of loneliness, higher levels of psychological distress, and lower levels of flourishing, with the greatest difference observed for daily marijuana users compared to non-users. However, these indicators of well-being did not significantly differ by levels of alcohol use frequency.”
There is a big social aspect of cannabis use as well though, especially in younger age groups. However, the inflection point when it stops being a social activity and turn in to dependence is different for different people and have many other underlying reasons.
Studies show that peer use is an important factor and, especially for younger people, substance use patterns follow the patterns in friend circles.
#Torrejón-Guirado MC, Baena-Jiménez MÁ, Lima-Serrano M, de Vries H, Mercken L. The influence of peer's social networks on adolescent's cannabis use: a systematic review of longitudinal studies. Front Psychiatry. 2023
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10768034/
Quote: “The most often found effect was the positive influence of friend cannabis use on adolescent cannabis use, meaning that adolescents are more likely to use cannabis if their close friends use cannabis. Yet, different operationalizations were used for assessing the influence of friends’ cannabis use. Other studies not included in this review, have also shown that the influence of peers is an important factor in cannabis use (11, 21, 22, 45). Although these studies did not take a network approach, they showed that adolescents are influenced by the perceived cannabis use of friends (modeling) (21, 22, 39), norms regarding cannabis use among Friends (11, 21, 22), and that they may experience pressure to conform to the behavior of their cannabis’ consuming Friends (22). Based on these studies and our results in the present review, we can conclude that it is important to consider the influences of peers in cannabis prevention efforts.”
#Phillips et al. Does social context matter? An ecological momentary assessment study of marijuana use among college students. Addictive Behaviors. 2018.
https://www.sciencedirect.com/science/article/abs/pii/S0306460318300042?via%3Dihub
Quote: “Past research has shown that young adults are likely to use substances in a similar manner as their friends (Andrews et al., 2002). Having more friends who use marijuana increases one’s own marijuana use during key times, particularly during the transition out of high school (White et al., 2006). In addition, perceived peer closeness with marijuana-using friends and being part of a more risky peer social network during college is associated with increased marijuana use frequency (Mason, Zaharakis & Benotsch, 2014). Recent work (Lipperman-Kreda et al., 2017) has demonstrated that the presence of intoxicated persons in one’s immediate environment increases the likelihood of simultaneous alcohol and marijuana use. Lastly, marijuana-specific injunctive (i.e., perceptions of others’ approval of marijuana use) and descriptive (i.e., beliefs about the quantity and frequency of marijuana use in others) norms have been shown to impact marijuana use among college students (Borsari & Carey, 2001; Buckner, 2013; Neighbors, Geisner, & Lee, 2008).
[...]
Marijuana use is a social activity. The present study included a number of novel findings. First, over three-quarters of marijuana use episodes reported by participants were in social contexts. Such figures have only rarely been reported in past EMA studies (e.g., Buckner et al., 2012; 2013). Second, while a number of participants reported using exclusively in social contexts, no participants reported using exclusively alone. This suggests that treatment and prevention efforts should target social use to have the broadest reach. Third, we were able to identify cannabis dependence, more time using marijuana in the moment, and using for social facilitation purposes as the strongest predictors of using marijuana in the context of being with others.”
– If you find yourself using it constantly, this can also stunt your development as a person. The numbness dulls bad feelings, making it easy not to deal with them. But in life you can only get over bad feelings if you actually feel them and you have to process them to grow.
– If you find yourself using it constantly, this can also stunt your development as a person. The numbness dulls bad feelings, making it easy not to deal with them. But in life you can only get over bad feelings if you actually feel them and you have to process them to grow.
#Cavalli JM, Cservenka A. Emotion Dysregulation Moderates the Association Between Stress and Problematic Cannabis Use. Front Psychiatry. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7820070/
Quote: “Several studies report that cannabis users experience emotion dysregulation and that emotion dysregulation is associated with cannabis use outcomes, such as higher cannabis consumption, cannabis abuse, and problematic cannabis use (35–38). Research suggests that cannabis users with greater emotion dysregulation are more apt to use cannabis as a coping mechanism (39, 40). Moreover, using cannabis as a coping mechanism for stress and negative affect has been found to mediate the relationship between emotion dysregulation and problematic cannabis use (41). Therefore, if individuals experiencing greater stress use cannabis to cope with stress and regulate negative affect, these individuals may be at risk of problematic cannabis use. Finally, emotion dysregulation mediates the relationship between depression, anxiety, and suicidal ideation and problematic cannabis use, further suggesting that a pathway to problematic use could be through an inability to effectively regulate negative emotions (42). Overall, research suggests that the development of problematic cannabis use could be attributed to users' emotion dysregulation, and a need to better regulate negative affect when under stressful conditions.”
#DeAngelis BN, al'Absi M. Regular cannabis use is associated with blunted affective, but not cardiovascular, stress responses. Addict Behav. 2020
https://pubmed.ncbi.nlm.nih.gov/32298953/
Quote: “To better understand the potential impact of chronic cannabis use on affective and cardiovascular responses to acute stress, we conducted a study examining positive affect, state stress, state anxiety, cannabis craving, blood pressure, and heart rate during rest and in response to acute stressors in a sample of regular cannabis users and non-users. The results provide evidence that cannabis use is associated with blunted positive and negative affective responses to acute stress. These findings replicate and extend previous research (Cuttler et al., 2017), which found blunted state stress responses among cannabis users. Our study design included measurement of cannabis craving at several timepoints before and after stress challenges, which allowed us to examine potential changes in cannabis craving in response to acute stress. Similar to one study (Cuttler et al., 2017), but unlike others (Buckner et al., 2013; Buckner et al., 2011), we did not find evidence of a stress effect on cannabis craving. Our design does not allow a direct test of previous researchers’ (Cuttler et al., 2017) speculation that stress-related increases in cannabis craving may be specific to users who experience high levels of social anxiety. Post-hoc examination of the correlation between stress-related changes (Post-Stress - Baseline 2) in cannabis craving and state anxiety, however, did not provide evidence of a substantial relationship between these indices (r = 0.09, p = .58).”
Following study suggests that among a group of over 400 students, ones who are more avoidant of repetition and routine have a higher likelihood of using cannabis.
#Doering EL, Weybright E, Anderson AJ, Murphy K, Caldwell L. Associations Between Trait Boredom and Frequency of Cannabis, Alcohol, and Tobacco Use in College Students. Cannabis. 2023
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10683743/
Quote: “Boredom susceptibility was a significant predictor of annual, monthly, and weekly cannabis and alcohol use, but only annual and monthly tobacco use. Boredom proneness was only a significant predictor for monthly alcohol use.
[...]
Two types of trait boredom, boredom proneness and boredom susceptibility, are each thought to be motivated by different underlying self-regulatory processes and are therefore differentially associated with risk behavior (Mercer-Lynn et al., 2011; Mercer & Eastwood, 2010). Boredom proneness is the tendency to experience boredom (Farmer & Sundberg, 1986), while boredom susceptibility is the “aversion to repetition, routine, and dull people, and restlessness when things are unchanging” (Zuckerman et al., 1978, p. 140).”
#Petrucci, A. S., LaFrance, E. M., & Cuttler, C. (2020). A Comprehensive Examination of the Links between Cannabis Use and Motivation. Substance Use & Misuse.
https://www.tandfonline.com/doi/full/10.1080/10826084.2020.1729203
Quote: “The present study revealed associations between various measures of cannabis use/misuse and apathy as well as between cannabis misuse and various aspects of motivation. However, the size of these correlations was small, indicating that cannabis accounts for less than 8% of the variance in motivation. Moreover, controlling for confounding differences in depression, personality, alcohol, and other substance use abolished most of these relationships, indicating that these variables explain much of the “amotivational syndrome” ascribed to cannabis use. Nevertheless, correlations between cannabis misuse and apathy and between cannabis use and fun-seeking remained significant even after controlling for these confounds.”
– Lastly, let us talk about physical withdrawal symptoms – the more you consume the worse they will be for you, especially if you use daily. Withdrawal can cause headaches, sweating or chills, decreased appetite, in severe cases even fever, nausea and abdominal pain.
– Lastly, let us talk about physical withdrawal symptoms – the more you consume the worse they will be for you, especially if you use daily. Withdrawal can cause headaches, sweating or chills, decreased appetite, in severe cases even fever, nausea and abdominal pain.
Contrary to what was believed earlier, cannabis induces physical withdrawal symptoms. The intensity of the symptoms change from person to person, depending on patterns of use and other psychological and environmental factors.
#Kesner AJ, Lovinger DM. Cannabis use, abuse, and withdrawal: Cannabinergic mechanisms, clinical, and preclinical findings. J Neurochem. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9291571/
Quote: “There appears to be a common misconception that cannabis withdrawal symptoms are mild, and therefore perhaps clinically irrelevant. In reality, there is strong evidence that cannabis withdrawal symptom severity is similar to that of tobacco/nicotine withdrawal (Budney & Hughes, 2006), and correlates with functional impairment and higher relapse rates (Allsop et al., ,2011, 2012; Chung et al., 2008). As with other drugs of abuse, several factors can contribute to the severity of cannabis withdrawal symptoms, such as psychiatric comorbidities, setting (inpatient or outpatient), duration of use prior to cessation, whether the individual is treatment seeking, and the rate of cessation (HealthQuest (NSW) 2008; Budney & Hughes, 2006; Budney et al., 2004). Regardless of the symptom profile, timeline, or severity, research has shown that 40%–50%, or more, of regular cannabis users will experience withdrawal symptoms (Bahji et al., 2020; Hasin et al., 2008).”
#Kesner AJ, Lovinger DM. Cannabis use, abuse, and withdrawal: Cannabinergic mechanisms, clinical, and preclinical findings. J Neurochem. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9291571/
Quote: “The DSM‐5 defines cannabis withdrawal as experiencing at least three of the following symptoms upon cessation of regular cannabis use: (1) Irritability/aggression, (2) nervousness/anxiety, (3) disrupted sleep, (4) hypophagia and weight loss, (5) restlessness, (6) depressed mood, (7) somatic symptoms causing discomfort, for example, abdominal pain, shakes, sweating, fever/chills, and headache (American Psychiatric Association, 2013). Other cannabis withdrawal symptoms have also been reported including vivid unpleasant dreams or nightmares (Budney et al., 2003), feeling tense or unable to achieve goals (Bahji et al., 2020), changes in libido, boredom, and craving cannabis (Copersino et al., 2006). Increased appetite and weight gain have also been observed in individuals abstaining from cannabis, but this is typically reported later in withdrawal (Copersino et al., 2006; Levin et al., 2010), and could potentially be a post‐withdrawal symptom (Boggs et al., 2013).
#Connor JP, Stjepanović D, Budney AJ, Le Foll B, Hall WD. Clinical management of cannabis withdrawal. Addiction. 2022
– You might have trouble falling asleep and if you do, you might have disturbing and vivid dreams.
– You might have trouble falling asleep and if you do, you might have disturbing and vivid dreams.
Unfortunately the sleep component tends to be one of the biggest problematic withdrawal symptoms. It also usually persists the longest and tends to be a primary reason for relapse.
#Babson, K.A., Sottile, J. & Morabito, D. Cannabis, Cannabinoids, and Sleep: a Review of the Literature. Curr Psychiatry Rep 19, 23 (2017).
https://link.springer.com/article/10.1007/s11920-017-0775-9#citeas
Quote: “Cannabis Withdrawal and Sleep Nonclinical and clinical research has now characterized the profile of cannabis withdrawal, with sleep disturbances and vivid dreams representing hallmark cannabis withdrawal symptoms [20]. Indeed disturbed sleep can last up to 45 days post-cessation making this the longest lasting withdrawal symptom [20]. Disturbed sleep is commonly reported with 67–73% of adults and 33–43% of adolescents reporting disturbed sleep during a quit attempt [14, 21, 22]. This work has combined to suggest that sleep disturbance is one of the most severe cannabis withdrawal symptoms [23].”
The following study found that in the first week of abstinence, frequent users took longer to fall asleep and had in general worse sleep but it came back to baseline by the fourth week.
#Baumer AM, Nestor BA, Potter K, Knoll S, Evins AE, Gilman J, Kossowsky J, Schuster RM. Assessing changes in sleep across four weeks among adolescents randomized to incentivized cannabis abstinence. Drug Alcohol Depend. 2023
https://pubmed.ncbi.nlm.nih.gov/37839357/
Quote: “Methods: Non-treatment seeking adolescents, recruited from school screening surveys and the community, with frequent cannabis use (MAge=17.8, SDAge=1.7, 47% female, 45% non-white) were randomized to four weeks of biochemically-verified abstinence, motivated via contingency management (CB-Abst, n=53), or monitoring without an abstinence requirement (CB-Mon, n=63). A mixed-effects model was used to predict change in Pittsburgh Sleep Quality Index (PSQI) scores.
Results: Participants in CB-Abst reported higher overall PSQI scores than those in CB-Mon (M=1.06, p=0.01) indicating worse sleep during the four-week trial. Sleep disruptions in CB-Abst increased during Week 1 of abstinence (d=0.34, p=0.04), decreased during Week 2 (d=0.36, p=0.04), and remained constant for the rest of the trial. At Week 4, sleep was comparable to baseline levels for those in CB-Abst (p=0.87). Withdrawal-associated sleep disruption in the CB-Abst group was circumscribed to increases in sleep latency (b=0.35; p=0.05).”
The actual timing can be different though. Following study, for example, suggests that the sleep related symptoms look similar to the control group by the third week of abstinence.
#Sullivan RM, Wallace AL, Stinson EA, Montoto KV, Kaiver CM, Wade NE, Lisdahl KM. Assessment of Withdrawal, Mood, and Sleep Inventories After Monitored 3-Week Abstinence in Cannabis-Using Adolescents and Young Adults. 2022.
https://pubmed.ncbi.nlm.nih.gov/34678051/
Quote: “In this study of nontreatment-seeking and physically healthy adolescents and young adults with no psychiatric comorbidities, regular cannabis-using participants reported significantly elevated withdrawal symptoms and peaking trajectories across 3 weeks of monitored abstinence compared to control participants. Moreover, cannabis-using participants reported more mood symptoms across the study period compared to controls, yet scores do not meet clinical thresholds. Cannabis-using group reported significantly elevated sleep-related withdrawal problems across abstinence, but by week-3 did not differ in overall sleep quality or duration compared to controls. Finally, cannabis-using participants did not differ on anxiety symptoms relative to control participants.” CWSC=The Cannabis Withdrawal Symptom Criteria
– The withdrawal can put you in a depressive mood where life feels daft and pointless. You can feel restless, angry, anxious or nervous. You may feel unable to do anything at all.
– The withdrawal can put you in a depressive mood where life feels daft and pointless. You can feel restless, angry, anxious or nervous. You may feel unable to do anything at all.
#Connor JP, Stjepanović D, Budney AJ, Le Foll B, Hall WD. Clinical management of cannabis withdrawal. Addiction. 2022
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9110555/
Quote: “Cannabis withdrawal refers to symptoms that occur after abrupt cessation or significant reductions in the use of cannabis products containing Δ9‐tetrahydrocannabinol (THC), the main psychoactive component in cannabis. These symptoms occur most often in regular and heavy cannabis users and the most common symptoms are anxiety, irritability, anger or aggression, disturbed sleep/dreaming, depressed mood and loss of appetite. Less commonly reported physical symptoms include chills, headaches, physical tension, sweating and stomach pain [1, 2]. Cessation of short‐term cannabidiol (CBD), a non‐psychoactive cannabinoid, does not appear to result in withdrawal [3].
[...]
The prevalence of cannabis withdrawal symptoms is higher in users with a history of daily cannabis use, concurrent cannabis and tobacco use and other substance use disorders [4].”
– After a few days these symptoms will begin to subside and after a few weeks they will be gone entirely – the exact time depends on how much and how long you have been consuming cannabis.
– After a few days these symptoms will begin to subside and after a few weeks they will be gone entirely – the exact time depends on how much and how long you have been consuming cannabis.
Withdrawal timeline differs from person to person depending on factors like frequency of use, amount used, use of other substances (including alcohol) and an individual’s physical and mental health. However, a broad timeline is reported in the following paper as a peak of symptoms at around 2-6 days and tapering off after three weeks. It is also important to note that there is a large amount of variation in the course and severity of cannabis withdrawal. Some patients report significant impairments to their day‐to‐day lives despite low doses and few CUD symptoms.
#Connor JP, Stjepanović D, Budney AJ, Le Foll B, Hall WD. Clinical management of cannabis withdrawal. Addiction. 2022
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9110555/
Quote: “Symptom onset typically occurs 24–48 hours after cessation and most symptoms generally peak at days 2–6, with some symptoms lasting up to 3 weeks or more in heavy cannabis users. The most common features of cannabis withdrawal are anxiety, irritability, anger or aggression, disturbed sleep/dreaming, depressed mood and loss of appetite. Less common physical symptoms include chills, headaches, physical tension, sweating and stomach pain.”
In a study with cannabis users of ages 16 to 26, researchers found that the withdrawal symptoms taper off after about three weeks. But they add that the subtle mood symptoms and sleep disorders might persist beyond three weeks.
#Sullivan RM, Wallace AL, Stinson EA, Montoto KV, Kaiver CM, Wade NE, Lisdahl KM. Assessment of Withdrawal, Mood, and Sleep Inventories After Monitored 3-Week Abstinence in Cannabis-Using Adolescents and Young Adults. Cannabis Cannabinoid Res. 2022
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9587800/
Quote: “In this study of nontreatment-seeking and physically healthy adolescents and young adults with no psychiatric comorbidities, regular cannabis-using participants reported significantly elevated withdrawal symptoms and peaking trajectories across 3 weeks of monitored abstinence compared to control participants. Moreover, cannabis-using participants reported more mood symptoms across the study period compared to controls, yet scores do not meet clinical thresholds. Cannabis-using group reported significantly elevated sleep-related withdrawal problems across abstinence, but by week-3 did not differ in overall sleep quality or duration compared to controls. Finally, cannabis using participants did not differ on anxiety symptoms relative to control participants.”
#Kesner AJ, Lovinger DM. Cannabis use, abuse, and withdrawal: Cannabinergic mechanisms, clinical, and preclinical findings. J Neurochem. 2021
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9291571/
Quote: “These symptoms also typically follow a reliable time course (Allsop et al., 2011; Budney et al., 2003; Hesse & Thylstrup, 2013), with sleep disturbances, somatic symptoms, and decreased appetite more prevalent during the initial several days of abstinence, followed by irritability, restlessness, and anxiety. Aggression and anger are more prominent after the first week or so of abstinence (Budney et al., 2003; Hesse & Thylstrup, 2013). Interestingly, while sleep disruption is strongest early in abstinence, vivid/unpleasant dreams can begin at a similar time point but extend for several weeks following cessation (Budney et al., 2003; Vorspan et al., 2010).”
– This section was not fun to research because there is fierce debate among researchers how bad weed is for your brain, and whether it has irreversible long term consequences or not. There is no consensus yet and it's hard to say anything definitive. Having said that, THC directly interferes with critical brain chemistry. There is some evidence that it MAY alter its structure. If it does, this may go away again if you quit after a few years. Or not. We don’t know yet.
– This section was not fun to research because there is fierce debate among researchers how bad weed is for your brain, and whether it has irreversible long term consequences or not. There is no consensus yet and it's hard to say anything definitive. Having said that, THC directly interferes with critical brain chemistry. There is some evidence that it MAY alter its structure. If it does, this may go away again if you quit after a few years. Or not. We don’t know yet.
The findings regarding changes in brain structure are mixed. There are not enough longitudinal studies investigating if the brain alterations happen before or after the cannabis use since most studies are done comparing users to nonusers at a specific point in time. It is difficult to assess from cross-sectional studies whether the differences are due to cannabis use or for example whether the differences were there already before cannabis use.
There are however several lines of research indicating that THC might cause changes in the brain upon adolescent onset of use. Even though we do not yet have a causal relationship from human studies, we have better evidence from animal studies where parameters can be more closely controlled therefore it is easier to establish causality.
Following is a recent review of the MRI studies conducted in the past 5 years summarizing the effects of frequent cannabis use and CUD on the brain.
#Colyer-Patel, K., Romein, C., Kuhns, L. et al. Recent Evidence on the Relation Between Cannabis Use, Brain Structure, and Function: Highlights and Challenges. Curr Addict Rep 2024
https://doi.org/10.1007/s40429-024-00557-z
Quote: “To date, the causal relationship between cannabis use and brain structure and functioning remains elusive. However, evidence suggests the persistence of alterations even after a period of abstinence lasting up to 25 days, highlighting the need for further investigation into the long-term effects following an extended period of abstinence. This review demonstrated the accumulating body of evidence supporting the impact of heavy use and CUD on brain structure, function, and cognition. However, findings also emphasize the necessity for studies to consider dependence status, age, sex, gender, tobacco and alcohol co-use, and tobacco and alcohol use histories when examining the effects of cannabis on the brain. By addressing these factors comprehensively, future research can provide a more complete understanding of the complex relationship between cannabis use and the brain.”
The following two studies are among the very rare longitudinal studies investigating the effects of adolescent cannabis use on the brain structure. One has found some structural changes however the other one didn't.
#Albaugh et al. Association of Cannabis Use During Adolescence With Neurodevelopment. JAMA Psychiatry. 2021
https://ajp.psychiatryonline.org/doi/10.1176/appi.ajp.2018.18020202
Quote: “To our knowledge, the present investigation represents the largest longitudinal neuroimaging study of cannabis use to date. Results suggest that cannabis use during middle to late adolescence may be associated with altered cortical development, particularly in prefrontal regions rich in CB1 receptors and exhibiting protracted maturational trajectories. Specifically, we found evidence of a dose-dependent association between cannabis use from baseline to 5-year follow-up and accelerated cortical thinning during that same period, primarily in prefrontal regions. Baseline cortical thickness was not associated with lifetime cannabis use at 5-year follow-up, suggesting that the observed neuroanatomical associations with lifetime cannabis use were not associated with preexisting differences in brain structure.”
#Meier MH, Schriber RA, Beardslee J, Hanson J, Pardini D. Associations between adolescent cannabis use frequency and adult brain structure: A prospective study of boys followed to adulthood. Drug Alcohol Depend. 2019
https://pubmed.ncbi.nlm.nih.gov/31357120/
Quote: “We found that adolescent cannabis use was not associated with adult brain structure in a sample of boys followed prospectively to adulthood. Boys were classified into one of four prototypical adolescent cannabis trajectory subgroups based on prospective assessments of cannabis use frequency from age 13–19: infrequent use/no use, desisting use, escalating use, or chronic-relatively frequent use. These subgroups showed different patterns of cannabis use across adolescence and differed in terms of their overall cumulative exposure to cannabis.
For example, the infrequent/no use subgroup had used cannabis, on average, on four total days from age 13–19, whereas the chronic-relatively frequent subgroup had used cannabis, on average, on 782 total days from age 13–19. We found no differences in adult brain structure for boys in the different adolescent cannabis trajectory subgroups. Even boys with the highest level of cannabis exposure in adolescence showed subcortical brain volumes and cortical brain volumes and thickness in adulthood that were similar to boys with almost no exposure to cannabis throughout adolescence.”
However there can also be confounding factors like accompanying alcohol use, that have to be taken into consideration while establishing causality. Findings from the following study constitutes a good example.
#Morin JG, Afzali MH, Bourque J, Stewart SH, Séguin JR, O'Leary-Barrett M, Conrod PJ. A Population-Based Analysis of the Relationship Between Substance Use and Adolescent Cognitive Development. Am J Psychiatry. 2019
https://pubmed.ncbi.nlm.nih.gov/30278790/
Quote: “Cannabis and alcohol models yielded evidence in favor of common vulnerability: individuals more likely to use cannabis or alcohol showed lower working memory, perceptual reasoning, and inhibitory control. These findings are in line with previous research (1, 3, 13, 28). In the combined model,our results suggest that the common vulnerability between working memory and cannabis was not significant over and above alcohol use and vice versa, suggesting that poor working memory could constitute a nonspecific common vulnerability to substance misuse in adolescence (3, 13). ”
– The consequences vary a lot between individuals but especially for heavy users they have a variety of potential unfunny downsides: The most common one is that your memory gets significantly worse. Sustained heavy use may lower your ability to learn, your reasoning, perception, attention span, decision making, language abilities and impulse control. Most negative effects seem to go away or at least weaken over time after you quit, but again we simply don’t know enough and need more research.
– The consequences vary a lot between individuals but especially for heavy users they have a variety of potential unfunny downsides: The most common one is that your memory gets significantly worse. Sustained heavy use may lower your ability to learn, your reasoning, perception, attention span, decision making, language abilities and impulse control. Most negative effects seem to go away or at least weaken over time after you quit, but again we simply don’t know enough and need more research.
The following review gathered the evidence up until 2019 on the short-term and long-term effects of cannabis.
#Kroon E, Kuhns L, Hoch E, Cousijn J. Heavy cannabis use, dependence and the brain: a clinical perspective. Addiction. 2020
#Hammond CJ, Chaney A, Hendrickson B, Sharma P. Cannabis use among U.S. adolescents in the era of marijuana legalization: a review of changing use patterns, comorbidity, and health correlates. Int Rev Psychiatry. 2020
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7588219/
Quote: “When not intoxicated, adolescent cannabis users exhibit signs of cognitive impairments when compared to matched controls in the domains of attention, memory, executive function (including working memory and inhibition), visual processing, and processing speed, along with decreased full-scale IQ and verbal IQ (Dougherty et al., 2013; Gruber, Sagar, Dahlgren, Racine, & Lukas, 2012; Jacobus, Bava, Cohen-Zion, Mahmood, & Tapert, 2009). Many of the domain specific cognitive deficits improve with abstinence, but some may persist beyond early abstinence and represent long-term deficits (Hanson et al., 2010; Medina et al., 2007; Meier et al., 2012; Volkow et al., 2016).
For example, a study by Hanson and colleagues found that following 3 weeks of abstinence from cannabis that adolescent regular cannabis users showed improvements in verbal memory and inhibition but continued to exhibit impaired attention compared to controls (Hanson et al., 2010). Studies of adolescents with earlier, heavier, and more persistent cannabis use patterns generally show larger effect sizes for cognitive outcomes (Gorey et al., 2019; Gruber et al., 2012; Meier et al., 2012; Pope et al., 2003). Some studies indicate that long-term cognitive impairments occur primarily in early adolescent-onset of cannabis users (≤ age of 15 or 16), and that adult- or late adolescent-onset of cannabis users do not exhibit the same risk for long-term cognitive impairments (Fontes et al., 2011; Gruber et al., 2012; Pope et al., 2003). Studies have also largely shown that adolescent-onset cannabis exposure produces similar cognitive deficits for both sexes (Levine, Clemenza, Rynn, & Lieberman, 2017; Meier et al., 2012; Pope et al., 2003).”
#Burggren AC, Shirazi A, Ginder N, London ED. Cannabis effects on brain structure, function, and cognition: considerations for medical uses of cannabis and its derivatives. Am J Drug Alcohol Abuse. 2019
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7027431/
Quote: “Mounting evidence points to cognitive impairment after chronic, heavy cannabis use (133–135), enduring beyond the acute effects, although there is also a large body of evidence with negative findings in cannabis users (136–138). In prospective studies of adolescents, findings regarding general intelligence are contradictory (56,139,140), but negative effects have been observed across a wide range of cognitive domains, including, but not limited to, various aspects of memory, executive function/working memory, and processing speed. Consistency in experimental design remains a challenging aspect of studying the long-term effects of chronic cannabis use on cognition (141).
Memory has been the cognitive domain most consistently impaired, with verbal learning and memory tasks particularly sensitive to the acute (142–144) and chronic (134) effects of cannabis. Several individual aspects of memory appear to be affected (46,134,145,146), with the most robust effects on verbal learning, including decrements in measures of encoding, recall, and recognition (see (134) for review). Associations between poorer performance in regular cannabis users and frequency, quantity, duration, and age of onset of cannabis use have also been reported (97,98,114,147,148). In long-term users, lasting impairments in memory and attention worsened with increasing years of regular cannabis use (135,140,149,150).”
#Meier MH, Caspi A, R Knodt A, Hall W, Ambler A, Harrington H, Hogan S, M Houts R, Poulton R, Ramrakha S, Hariri AR, Moffitt TE. Long-Term Cannabis Use and Cognitive Reserves and Hippocampal Volume in Midlife. Am J Psychiatry. 2022
https://pubmed.ncbi.nlm.nih.gov/35255711/
Quote: “Long-term cannabis users showed IQ decline from childhood to midlife (mean=−5.5 IQ points), poorer learning and processing speed relative to their childhood IQ, and informant-reported memory and attention problems. These deficits were specific to long-term cannabis users because they were either not present or smaller among long-term tobacco users, long-term alcohol users, midlife recreational cannabis users, and cannabis quitters. Cognitive deficits among long-term cannabis users could not be explained by persistent tobacco, alcohol, or other illicit drug use; childhood SES; low childhood self-control; or family history of substance dependence. Long-term cannabis users showed smaller hippocampal volume, but smaller hippocampal volume did not statistically mediate cannabis-related cognitive deficits.”
#Burggren AC, Shirazi A, Ginder N, London ED. Cannabis effects on brain structure, function, and cognition: considerations for medical uses of cannabis and its derivatives. Am J Drug Alcohol Abuse. 2019
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7027431/
Quote: “Maladaptive decision-making has been demonstrated in cannabis users (99–101,128,160,161). In one case, performance below control levels on a reward-based decision-making task was seen in participants who had been abstinent for 25 days (102). Yet, in other studies of impulsive behavior tasks (i.e., Iowa Gambling Task, Go-Stop Task, Monetary Choice Questionnaire, and Balloon Analogue Risk Task (127)) and a monetary risk-taking task (103) current users did not differ from controls. In addition, delay discounting performance did not differ between current and abstinent users and control subjects (103). Thus, whereas acute intoxication by THC appears to increase risky decision-making and sensitivity to reward, the extent to which these effects persist in chronic or abstinent users remains unclear.”
Jacobus J, Squeglia LM, Infante MA, Castro N, Brumback T, Meruelo AD, Tapert SF. Neuropsychological performance in adolescent marijuana users with co-occurring alcohol use: A three-year longitudinal study. Neuropsychology. 2015 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4633396/
Quote: “This study evaluated adolescents reporting heavy marijuana and alcohol use, and control teens with minimal substance over three-years. Group differences, controlling for lifetime alcohol use, were observed in the domains complex attention, memory, processing speed, and visuospatial functioning. While MJ+ALC performed worse than controls across all three time points, significant differences were more consistent at 19 years old (1.5-year follow-up) across domains, just prior to a narrowing substance use gap observed by age 20 (3-year follow-up) between our users and controls for both alcohol and marijuana use. Our sample use trajectories are consistent with epidemiological research that shows marijuana use tends to peak around 18-19 years old in the United States (spanning baseline to 1.5-year follow-up) for those who do not transition to chronic heavy use (Caldeira, et al., 2012; Johnston, et al., 2014). Poorer cognitive performance in our users (at 1.5-year follow-up) compared to those with more minimal use histories corresponds with the epidemiological literature on age of peak use, and differences are observed in domains important for optimal cognitive performance.”
– Where the evidence is much clearer is that consuming a lot of weed is really bad for teenagers on multiple levels. If you start using heavily, early, you have many more years to build up potential negative side effects. Teens who use a lot are much more likely to become addicted to weed.
– Where the evidence is much clearer is that consuming a lot of weed is really bad for teenagers on multiple levels. If you start using heavily, early, you have many more years to build up potential negative side effects. Teens who use a lot are much more likely to become addicted to weed.
It is especially bad for teenagers for a couple of reasons. First, starting early increases the chances of developing a CUD and with increased severity. Second, early onset users are likely to have more cannabis related harm and poorer life outcomes. Some researchers suggest that it becomes more likely for them to turn to cannabis use as a coping mechanism with difficulties with life, when other coping mechanisms are absent. There is also some line of evidence that early use is detrimental for brain development and cognitive functioning but more research is needed here to say something more conclusive.
Following study suggests that adolescents had a 3.5 times greater odds of having severe CUD than adults.
#Lawn W, Mokrysz C, Lees R, Trinci K, Petrilli K, Skumlien M, Borissova A, Ofori S, Bird C, Jones G, Bloomfield MA, Das RK, Wall MB, Freeman TP, Curran HV. The CannTeen Study: Cannabis use disorder, depression, anxiety, and psychotic-like symptoms in adolescent and adult cannabis users and age-matched controls. J Psychopharmacol. 2022
https://pubmed.ncbi.nlm.nih.gov/35772419/
Quote: “Conclusion: Adolescent cannabis users are more likely than adult cannabis users to have severe CUD. Adolescent cannabis users have greater psychotic-like symptoms than adult cannabis users and adolescent controls, through an additive effect. There was no evidence of an amplified vulnerability to cannabis-related increases in subclinical depression, anxiety or psychotic-like symptoms in adolescence. However, poorer mental health was associated with the presence of severe CUD.
[...]
We speculate that adolescents may be more sensitive to the development of CUD than adults for a number of reasons, including greater disruption of interpersonal relationships, for example, with parents or teachers; a hyper plastic brain and a developing endocannabinoid system (Meyer et al., 2018); a more malleable social life and evolving sense of identity which can quickly shift towards cannabis use (Hammersley et al., 2001); potentially subtle differences in acute effects of cannabis (Mokrysz et al., 2016; Murray et al., 2022); a greater desire to binge on cannabis (Borissova et al., 2022); and a drive towards social attunement (Cousijn et al., 2018). However, research into the different profiles of adolescent and adult CUD, and the neuropsychopharmacological predictors of CUD onset in adolescents is needed.”
#Lees R, Lawn W, Petrilli K, Brown A, Trinci K, Borissova A, Ofori S, Mokrysz C, Curran HV, Hines LA, Freeman TP. Persistent increased severity of cannabis use disorder symptoms in adolescents compared to adults: a one-year longitudinal study. Eur Arch Psychiatry Clin Neurosci. 2024
https://pubmed.ncbi.nlm.nih.gov/38709252
Quote: “In this one-year, longitudinal investigation of adolescents and adults who use cannabis, we found that adolescents (aged 16–17) scored on average 3.7 points higher on the CUDIT-R than adults (aged 26–29) across all 5 assessment waves (3.68, 95% CIs 1.81, 5.56). This efect was only partially attenuated after adjustment for gender, COVID-19, and mean weekly standard THC units (3.66 95% CIs 1.99, 5.34). CUD symptoms decreased linearly over the year in both age groups (−0.47, 95%CIs −0.67, −0.27). Through the use of a longitudinal study with fve assessment waves, and a comprehensive standardised assessment of cannabis exposure, these fndings show that the increased number of CUD symptoms that have been observed in adolescents persists over 12 months and is robust after adjustment for variation in THC dose.”
#Millar, S.R., Mongan, D., Smyth, B.P. et al. Relationships between age at first substance use and persistence of cannabis use and cannabis use disorder. BMC Public Health 21, 997 (2021).
https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-021-11023-0
Quote: “In this study we used data from Ireland’s 2010/11 and 2014/15 National Drug Prevalence Surveys to determine relationships between age at first use of alcohol, tobacco and cannabis and patterns of cannabis use, frequency of use within the last 30 days and whether age at first substance use was related to having a CUD. For the full sample, when compared to former users, the odds of being a current cannabis user were found to be reduced by 11% and 4% for each year of delayed alcohol and cannabis use onset, respectively. Among subjects who indicated current cannabis use, significant inverse linear relationships were noted, with increasing age of first use of tobacco and cannabis being associated with a decreased frequency of cannabis use within the last 30 days. In addition, fully adjusted models demonstrated relationships between age at first use of tobacco and cannabis and having a CUD among subjects aged 15–34 years of age.”
Findings from a 20-year longitudinal study from Australia suggested that early-age onset regular users had poorer life outcomes, measured over financial hardships, relationship and employment status, other substance abuses, compared to minimal or non-users.
#Chan GCK, Becker D, Butterworth P, Hines L, Coffey C, Hall W, Patton G. Young-adult compared to adolescent onset of regular cannabis use: A 20-year prospective cohort study of later consequences. Drug Alcohol Rev. 2021
https://pubmed.ncbi.nlm.nih.gov/33497516/
Quote: “Results: Substantially more participants (13.6%) initiated regular use after high school (young-adult onset) than in adolescence (7.7%, adolescent onset). By the mid-30s, both young-adult and adolescent-onset regular users were more likely than minimal/non-users (63.5%) to have used other illicit drugs (odds ratio [OR] > 20.4), be a high-risk alcohol drinker (OR > 3.7), smoked daily (OR > 7.2) and less likely to be in relationships (OR < 0.4). As the prevalence of the young-adult-onset group was nearly double of the adolescent-onset group, it accounted for a higher proportion of adverse consequences than the adolescent-onset group.
Discussion and conclusions: Cannabis users who began regular use in their teens had poorer later life outcomes than non-using peers. The larger group who began regular cannabis use after leaving high school accounted for most cannabis-related harms in adulthood. Given the legalisation of cannabis use in an increasing number of jurisdictions, we should increasingly expect harms from cannabis use to lie in those commencing use in young adulthood.
[...]
The similarities in outcomes between these two groups were particularly striking (e.g. over 60% of those in the adolescent and young-adult-onset regular groups engaged in highrisk drinking, compared to 25% in the minimal/nonuse group and 41% in the occasional use group; see Table 1 for other comparisons), given their very distinct risk profiles in mid-adolescence: adolescent-onset regular users had higher levels of adolescent smoking, antisocial behaviour and cannabis using peers than those initiating use after leaving school. Our hypotheses that adolescent onset of regular cannabis use would be associated with the worst psychosocial sequelae at age 35, followed by young-adult-onset and then minimal users, were supported.”
There might also be structural and functional changes in brain and cognitive deficits with early onset of use. However the findings there are currently uncertain or have small effects. Currently they are pointing to some small cognitive deficits caused by frequent cannabis use however we don’t know if they are irreversible or not. There is definitely a need for more research there to say something more conclusive.
A recent review summarized the research in the following key take-aways:
#Scott JC. Impact of Adolescent Cannabis Use on Neurocognitive and Brain Development. Psychiatr Clin North Am. 2023
https://pubmed.ncbi.nlm.nih.gov/37879830/
Quote: “KEY POINTS
– Converging evidence indicates that ongoing, frequent cannabis use in adolescence is associated with small reductions in neurocognitive functioning.
– Abstinence from cannabis is likely to lead to some recovery in cognitive functioning in adolescents.
– Adolescent-onset, sustained, long-term use of cannabis may result in cognitive deficits that do not recover as readily with abstinence.
– There is some evidence that cannabis use in adolescence is associated with differences in brain structure, but these findings need replication.”
– This may just be correlation and weed may not be the original reason, but heavy weed users are more likely to perform poorly in school and less likely to finish their education.
– This may just be correlation and weed may not be the original reason, but heavy weed users are more likely to perform poorly in school and less likely to finish their education.
#Lorenzetti V, Hoch E, Hall W. Adolescent cannabis use, cognition, brain health and educational outcomes: A review of the evidence. Eur Neuropsychopharmacol. 2020
https://pubmed.ncbi.nlm.nih.gov/32268974/
Quote: “Longitudinal studies and some twin studies have found that cannabis users are less likely to complete secondary school than their non-using controls. This association might reflect an effect of cannabis use and/or the social environment of cannabis users and their cannabis using peers. Cognitive performance is altered in some domains (e.g. IQ, verbal learning) in young people while they are regularly using cannabis. There are two important messages to adolescents and young adults: First, cannabis has potentially detrimental effects on cognition, brain and educational outcomes that persist beyond acute intoxication. Second, impaired cognitive function in cannabis users appears to improve with sustained abstinence.”
It is important to note that there might be several confounding factors and, educational outcomes and cannabis use could both be due to the same environmental risk factors.
#Verweij et al. Is the relationship between early-onset cannabis use and educational attainment causal or due to common liability? 2013
https://www.sciencedirect.com/science/article/abs/pii/S0376871613002998
Quote: “Results: We find a significant phenotypic correlation between early-onset cannabis use and early school leaving (r = 0.26), which could be explained by familial influences (of genetic and/or shared environmental origin). The pattern of odds ratios found in the co-twin control design is not consistent with direct causation, but rather suggests that the association is due to shared environmental factors influencing both variables.
Conclusion: Our findings suggest that the relationship between early-onset cannabis use and school leaving is due to shared environmental risk factors influencing both the risk of early-onset cannabis use and early school leaving.”
– They are on average less satisfied with their life and what they achieved.
– They are on average less satisfied with their life and what they achieved.
There are not an awful lot of studies looking into the relation between life satisfaction and cannabis. And even the few that do so, have difficulties establishing the causality since the relation can also be bidirectional: people who are less satisfied with their lives could be more likely to use cannabis and this makes the interpretation of the cross-sectional studies difficult. So currently there is no consensus on the causality.
#Deligianni ML, Studer J, Daeppen JB, Gmel G, Bertholet N. Longitudinal Associations Between Life Satisfaction and Cannabis Use Initiation, Cessation, and Disorder Symptom Severity in a Cohort of Young Swiss Men. Int J Environ Res Public Health. 2019
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6518131/
Quote: “Only a few studies have explored the relationship between life satisfaction and cannabis use [6,10,11,18,19,20,21,22,23,24,25,26], and these studies mainly used cross-sectional designs, or, when using longitudinal designs, only tested the prospective association of cannabis use on later satisfaction with life. Prospective studies showed that cannabis does not have a positive impact on satisfaction with life among young adults, but has rather the opposite effect [6,21,26]. To our knowledge, only two longitudinal studies investigated associations between life satisfaction and later cannabis use, and those results were inconsistent. A recent longitudinal study conducted in Australia suggests that lower life satisfaction during early adolescence is associated with the onset of cannabis use in young adulthood [21]. In contrast, a more recent study among disadvantaged Australians failed to support any significant associations between life satisfaction and later cannabis use [27]. Nevertheless, some authors proposed that cannabis use might be motivated by unsatisfactory life conditions [20]. Therefore, consensus is lacking regarding the influence of life satisfaction on cannabis use.”
#Tartaglia et al. Life Satisfaction and Cannabis Use: A Study on Young Adults. J Happiness Stud. 2016.
https://link.springer.com/article/10.1007/s10902-016-9742-0
Quote: “Satisfaction with life was negatively related to cannabis use. This result is consistent with other studies that found a relationship between low levels of life satisfaction, general happiness, and cannabis use (Georgiades and Boyle 2007; Gruber et al. 2003). A possible interpretation of this result is that cannabis use may be motivated by coping with unsatisfactory life conditions (Fox et al. 2011).”
Also, substance abuse in general is associated with life dissatisfaction. However, it is important to note that life satisfaction is a complex measure and has many different aspects to it. So what we mention here is an observational statement rather than coming from studies that pinpointed the causality.
#Zullig et al. Relationship Between Perceived Life Satisfaction and Adolescents’ Substance Abuse. 2001.
https://pubmed.ncbi.nlm.nih.gov/11587912/
Quote: “Results suggest that a substantial number of public high school students are reporting dissatisfaction with their lives. This study also suggests that a substantial number of public high school adolescents are also engaging in substance abuse behaviors. Most importantly, this study identified significant relationships between self-reported LS and substance use behaviors. Furthermore, this study demonstrated the importance of two contextual factors as moderators of the relationships between life satisfaction and specific types of substance use. That is, the nature and magnitude of the substance use: life satisfaction associations were significantly influenced by both student gender and ethnicity.”
[...]
With the exception of black females using marijuana for the first time after the age of 13 years, and black males past 30 day use of marijuana, all four marijuana behaviors were significantly associated with reports of life dissatisfaction. Literature in this regard suggests that early use of marijuana has consequences for later psychological development [39]. Young people who have used marijuana on ten or more occasions have been reported to be significantly more likely to have come from socially disadvantaged backgrounds, to have been exposed to family adversities during childhood, to have formed affiliations with delinquent or substance-using peers, to have reported poorer parental attachment, and to have adjustment difficulties and problems by age 16 [40].”
There are also findings suggesting that adolescents who do not continue using into their twenties have similar life satisfaction compared to nonusers.
#The University of Queensland. Life success remains high despite adolescent drug use. 2022.
Quote: “Emeritus Professor Jake Najman said the research was the first to consider persistent use, rather than the age of first consumption, when predicting adult life success in adolescent drug users.
“We found no significant impact on adult life in study participants who started using cannabis, or cannabis and amphetamine before turning 21, but who stopped before they reached the age of 30,” Professor Najman said.
“However, we found people who used cannabis and amphetamines at 30 had substantially lower levels of life success.”"
– And there is strong evidence that teens users are way more likely to develop mental health issues like psychosis, schizophrenia, depression or anxiety later in life. Once again, the younger you start, the higher the risk – and it also seems to rise massively with high THC doses, making highly potent cannabis products even more dangerous for teens.
– And there is strong evidence that teens users are way more likely to develop mental health issues like psychosis, schizophrenia, depression or anxiety later in life. Once again, the younger you start, the higher the risk – and it also seems to rise massively with high THC doses, making highly potent cannabis products even more dangerous for teens.
In the following we added references for each condition. It is important to note that even though this relationship is very strong, it is still very difficult to ascertain causality.
Depression:
#Langlois C, Potvin S, Khullar A, Tourjman SV. Down and High: Reflections Regarding Depression and Cannabis. Front Psychiatry. 2021
https://pubmed.ncbi.nlm.nih.gov/34054594/
Quote: “The evidence from longitudinal studies suggest that there is a bidirectional relationship between cannabis use and depression, such that cannabis use increases the risk for depression and vice-versa. This risk is possibly higher in heavy users having initiated their consumption in early adolescence. Clinical evidence also suggests that cannabis use is associated with a worse prognosis in individuals with major depressive disorder.”
#Mustonen A, Hielscher E, Miettunen J, Denissoff A, Alakokkare AE, Scott JG, Niemelä S. Adolescent cannabis use, depression and anxiety disorders in the Northern Finland Birth Cohort 1986. BJPsych Open. 2021
https://pubmed.ncbi.nlm.nih.gov/36043688/
Quote: “Results: We included 6325 participants (48.8% male) in the analyses; 352 (5.6%) participants reported cannabis use until 15-16 years of age. By the end of the follow-up, 583 (9.2%) participants were diagnosed with unipolar depression and 688 (10.9%) were diagnosed with anxiety disorder. Cannabis use in adolescence was associated with an increased risk of depression and anxiety disorders in crude models. After adjusting for parental psychiatric disorder, baseline emotional and behavioural problems, demographic factors and other substance use, using cannabis five or more times was associated with increased risk of anxiety disorders (hazard ratio 2.01, 95% CI 1.15-3.82), and using cannabis once (hazard ratio 1.93, 95% CI 1.30-2.87) or two to four times (hazard ratio 2.02, 95% CI 1.24-3.31) was associated with increased risk of depression.”
Anxiety:
#Lowe DJE, Sorkhou M, George TP. Cannabis use in adolescents and anxiety symptoms and disorders: a systematic review and meta-analysis. Am J Drug Alcohol Abuse. 2024
https://pubmed.ncbi.nlm.nih.gov/38285048/
Quote: “Six longitudinal studies were identified for quantitative analysis, while twelve non-overlapping longitudinal studies were identified for qualitative review (total N = 18; 33380 subjects). Meta-analytical findings supported an association between adolescent cannabis use and the development of a subsequent anxiety disorder (Odds Ratio = 2.14, 95% CI: 1.37-3.36, p < .01). These findings were consistent with our qualitative synthesis where nine of the twelve longitudinal studies observed a significant relationship between adolescent cannabis use and exacerbation of anxiety symptoms later in life, irrespective of an anxiety disorder diagnosis. Discussion: In summary, the current evidence suggests a prospective association between adolescent cannabis use and later anxiety symptoms and disorders. These findings underscore the importance of refining research methodologies, considering sex-based differences and controlling for confounding factors, as well as implementing educational initiatives and developing clinical interventions to address the mental health risks associated with cannabis use among adolescents.”
Psychosis and schizophrenia:
#Malone DT, Hill MN, Rubino T. Adolescent cannabis use and psychosis: epidemiology and neurodevelopmental models. Br J Pharmacol. 2010
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2931552/
Quote: “A recent study found that cannabis use was significantly associated with a decrease in age of onset of schizophrenia (Sugranyes et al., 2009). This is concerning as the early onset of schizophrenia has been proven to be a negative outcome factor (Malla and Payne, 2005; Rabinowitz et al., 2006). A study in Spain found that patients presenting with first episode psychosis (average age 15.5 years) had a higher rate of positive symptoms and less negative symptoms if they were cannabis users compared with non-cannabis users (Baeza et al., 2009). In addition, the increases in cannabis use in the UK population over the last 30 years as reported by Hickman et al. (2007) were concluded by the authors to be mainly due to more prolonged use initiated at younger ages (Hickman et al., 2007). Thus, despite some variables factors such as the measurement of psychotic symptoms and control for confounding factors, it appears that there is a causal link between adolescent cannabis use and the development of psychoses such as schizophrenia. With a greater amount of adolescents consuming cannabis, it has become imperative to critically evaluate whether this age group is particularly vulnerable to developing psychoses such as schizophrenia compared with adolescents that do not consume cannabis, and to elucidate mechanisms responsible for this vulnerability.”
It is important to note that though currently most research on anxiety and cannabis use is correlational. Some researchers have suggested that cannabis increases the likelihood of anxiety in the genetically vulnerable users.
#Otten R, Huizink AC, Monshouwer K, Creemers HE, Onrust S. Cannabis use and symptoms of anxiety in adolescence and the moderating effect of the serotonin transporter gene. Addict Biol. 2017
https://pubmed.ncbi.nlm.nih.gov/26860734/
Quote: “Specifically, we concentrated on changes in cannabis use and symptoms of anxiety over time and differences herein for individuals with and without the short allele of the 5-HTTLPR genotype. Data were from 1424 adolescents over a period of 5 years. We used different statistical analyses to test co-development of cannabis use and symptoms of anxiety throughout adolescence and the possible role of the 5-HTTLPR genotype in this process. Results from different analyses showed that cannabis use is associated with an increase in symptoms of anxiety, but only in carriers of the short allele of the 5-HTTLPR genotype, not in non-carriers. The findings of the present study show first evidence that the links between cannabis use and symptoms of anxiety are conditional on the individuals' genetic make-up.”
#Rubino T, Zamberletti E, Parolaro D. Adolescent exposure to cannabis as a risk factor for psychiatric disorders. J Psychopharmacol. 2012
https://pubmed.ncbi.nlm.nih.gov/21768160/
Quote: “ In the same line McGrath et al. (2010), using a sibling pair analysis nested within a prospective birth cohort, demonstrated that early cannabis use is associated with psychosis-related outcomes in young adults. The use of sibling pair analysis provides the opportunity to control for a range of unmeasured potential confounding variables, thus making the results more compelling. Interestingly, the inverse relationship has also been demonstrated: that is, the presence of psychotic symptoms in those who had never used cannabis predicted future cannabis use (for a review see Dekker et al., 2009). This association between cannabis consumption and subsequent psychotic illness appears to be highly dependent on the age when drug use begins. For example, in a New Zealand study initiation by the age of 18 years doubled, whereas initiation by 15 years quadrupled, the odds of subsequent psychotic disorders at follow-up at the age of 26 years (Arseneault et al., 2002).
Moreover, cannabis use at a younger age relates to an earlier onset of psychotic symptoms (Dragt et al., 2010; Sugranyes et al., 2009). The reasons underlying the greater effect observed in those who begin cannabis use early in adolescence is still unclear. However, as previously mentioned in this review significant changes in the brain occur during adolescence and drugs of abuse affect brain circuits involved in reward, decision making, attention, learning and memory, and behavioral control, all of which are still maturing into early adulthood, and cannabis use in this period may lead to alterations in neurobiology that increase psychosis risk.”
Several studies indicated that the relation is dose-dependent.
#Di Forti M, Morgan C, Dazzan P, Pariante C, Mondelli V, Marques TR, Handley R, Luzi S, Russo M, Paparelli A, Butt A, Stilo SA, Wiffen B, Powell J, Murray RM. High-potency cannabis and the risk of psychosis. Br J Psychiatry. 2009 Dec;195(6):488-91. doi: 10.1192/bjp.bp.109.064220. PMID: 19949195; PMCID: PMC2801827.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2801827/
Quote: “Patients experiencing a first episode of psychosis were not more likely to have ever taken cannabis or to have started doing so earlier than the control group. This is not surprising because cannabis consumption is very common among adolescents in the UK: 40% of British children aged 15–16 years have used cannabis.1 However, psychosis was associated with more frequent and longer use of cannabis. This confirms previous suggestions that the risks of both transient psychotic symptoms and schizophrenia in those who use cannabis are dose-related.6
Our most striking finding is that patients with a first episode of psychosis preferentially used high-potency cannabis preparations of the sinsemilla (skunk) variety. In south-east London this form of cannabis is estimated to contain between 12% and 18% Δ9-THC and less than 1.5% cannabidiol. In contrast, those in the control group who used cannabis were more likely to consume resin (hash), with an average Δ9-THC concentration of 3.4% and a similar proportion of cannabidiol.9”
#Hines LA, Freeman TP, Gage SH, et al. Association of High-Potency Cannabis Use With Mental Health and Substance Use in Adolescence. JAMA Psychiatry. 2020
https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2765973
Quote: “The present study restricts analyses to individuals who have used different forms of cannabis to inform understanding of the implications of the proliferation of high-potency cannabis in legal markets.4,5 In a general population sample of young people in the UK, individuals who use high-potency cannabis (compared with those using lower-potency forms of cannabis) are more likely to be using cannabis regularly, more likely to report having recently experienced problems associated with their cannabis use, and more likely to concurrently be experiencing use of other illicit drugs, tobacco dependence, AUD, generalized anxiety disorder, and PEs. After adjustment for age at onset of cannabis use or for early adolescent measures of psychopathologic conditions and frequency of cannabis use, high-potency cannabis was associated with increases in the likelihood of frequent cannabis use, having recently experienced problems associated with cannabis use, and the likelihood of experiencing generalized anxiety disorder. The results provide a profile of individuals who use high-potency cannabis, indicating that this behavior is more common among individuals who are male, grow up in families with a low socioeconomic status, experience early PEs, and report early-onset cannabis use.”
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