Schacter Chapter Fifteen: Psychological Disorders
A mental disorder is defined as: a persistent disturbance or dysfunction in behavior, thoughts, or emotions that causes significant distress or impairment, both to self and others.
According to the theory of physiognomy, mental disorders could be diagnosed from facial features. This fanciful theory is now considered superstition but was popular from antiquity until the early twentieth century.
Over the past 200 years, the new way of looking at psychological abnormalities is the medical model, in which abnormal psychological experiences are conceptualized as illnesses that, like physical illnesses, have biological and environmental causes, defined symptoms, and possible cures.
Conceptualizing abnormal thoughts and behaviors as illnesses suggests that a first step is to determine the nature of the problem through diagnosis.
It is important to note the differences among three related general medical and classification terms:
(1) a disorder refers to a common set of signs and symptoms;
(2) a disease is a known pathological process affecting the body;
(3) a diagnosis is a determination as to whether a disorder or disease is present (Kraemer, Shrout, & RubioStipec, 2007).
Knowing that a disorder is present (or diagnosed) does not necessarily mean that we know the underlying disease process in the body that gives rise to the signs and symptoms of the disorder. Note this is a practical application of the 'confounding variable' or the 'latent variable' concept.
Some psychologists argue that the medical model 'medicalizes' or 'pathologizes' normal human behavior. For instance, extreme sadness can be considered to be major depression; extreme shyness can be diagnosed as social anxiety disorder; trouble concentrating in school can be considered to be attention deficit disorder. Note: these concerns are a practical example of 'state versus trait' that we studied in the Personality chapter.
Classifying Mental Disorders
The most widely used classification system in North America is the Diagnostic and Statistical Manual of Mental Disorders (DSM5). The DSM5 is a classification system that describes the features used to diagnose each recognized mental disorder and indicates how the disorder can be distinguished from other, similar problems. Most of those with a mental disorder (greater than 80%) exhibit comorbidity, which refers to the co-occurrence of two or more disorders in a single individual. (Gadermann et al., 2012).
The medical model also suggests that each category of mental disorder is likely to have a common prognosis, a typical course over time and susceptibility to treatment and cure.
Here the weakness of the medical model becomes apparent, as it is rarely useful to focus on a single cause that is internal to the person and that suggests a single cure. Note: this is another variety of the 'correlation versus causation' problem.
Disorder
Main DSM5 Categories of Mental Disorders
Definition
Example
Neuro-developmental Impairments in thinking
Autism Spectrum Disorder
Schizophrenia/PsychoticDisturbances of thought & mood Paranoia
BipolarMajor mood flucuationsPsychotic breaks
DepressiveExtreme, persistent periods of
depressed moodDysthymia (male)
AnxietyExtreme fear impairs functioning Panic disorder
ObsessiveCompulsiveobsessive repetitive thinking &
actingHandwashing rituals,
germophobia
DissociativeDisruptions in consciousnessDID, fugue
SomaticSignificant distress from pain or Repeatedly checking your body
fatigue
for abnormalities
Feeding/EatingImpairment of health wrt foodAnorexia nervosa, bulimia
EliminationInappropriate elimination of
urine or fecesCoprophilia
Sleeping/WakingProblems with sleep/wake cycleInsomnia, narcolepsy
Sexual DysfunctionUnsatisfactory sexual activityErectile dysfunction
Gender DysphoriaIncongruence between person's Transgender difficulties after
experienced gender and assigned gender reassignment
gender
Disruptive/Impulse ControlProblems controlling emotionsConduct disorder, kleptomania
Substance Abuse / AddictionPersistent use of substances
leading to significant distressOpioids, also gambling
NeurocognitiveDisorders of ThinkingAlzheimer's
PersonalityThinking, feeling, behaving,
leading to significant problemsNarcissistic Personality Disorder
ParaphilicInappropriate sexual activityPedophilia
Other/ResidualDoes not fit other categories, but Medical conditions
associated with significant
distress
Adverse Effects of MedicationProblems with physical
movementTardive Dyskinesia
Focus of Clinical AttentionRelationship problemsAbuse & neglect
TraumaWhat do mental disorders look like in different parts of the world? Depression, anxiety, attention deficit/hyperactivity disorder, and substance abuse are seen all over the globe (Kessler et al., 2007) This leads to the biopsychosocial perspective, which explains mental disorders as the result of interactions among biological, psychological, and social factors. The biological focuses on genetic and epigenetic influences, biochemical imbalances, and abnormalities in brain structure and function.
The psychological focuses on maladaptive learning and coping, cognitive biases, dysfunctional attitudes, and interpersonal problems.
The social factors include poor socialization, stressful life experiences, cultural and social inequalities. The interaction of the forces leads to the diathesis-stress model, which suggests that a person may be predisposed for a psychological disorder that remains unexpressed until triggered by stress.
Let's try an example for schizophrenia ('shattered mind') Brown, Columbia University (2004), identified that approximately 14% of schizophrenia cases seem to have been caused by influenza during pregnancy.
Another example from neuroscience: variations in a gene (DRD2) the codes for dopamine receptors are associated with abnormalities in connectivity between parts of the frontal lobe and the striatum.
This lack of connectivity is related to impulsiveness and responsiveness to rewards associated with a range of addictive behavior disorders (Buckholtz & MeyerLindenberg, 2012).
As the currently available body of knowledge about mental disorders grows, the field is moving beyond simple descriptive diagnostic categories towards ones based on the biopsychosocial approach.
How is this done? Using structured clinical interview technique, that decide whether a person meets the given criteria for a disorder (Nock et al., 2007). According to the DSM5, a person must have at least five of the nine symptoms of major depressive disorder to meet the criteria. Client self-report of symptoms is also called phenomenological assessment, and also has a structured analysis guidelines.
There a serious dangers in labelling, because the stigma of being 'mentally ill' can have lifelong consequences. One set of studies followed the lives of patients who were thought to be too dangerous to release, and had therefore been kept in the back wards of institutions for years. Their release showed that those with a mental disorder are no more likely to be violent than those without a disorder.
(Elbogen & Johnson, 2009).Anxiety Disorders
Situation-related anxiety is normal and adaptive. When anxiety arises that is out of proportion to real threats and challenges, however, it is maladaptive. There is significant comorbidity between anxiety and depression. (Beesdo et al., 2010).
The DSM5 lists phobic, panic, and generalized anxiety disorders.
Phobias involve excessive and persistent fear of a specific object, activity, or situation. Some phobias may be learned through classical conditioning, in which a conditioned stimulus (CS) that is paired with an anxiety-evoking unconditioned stimulus (US) itself comes to elicit a conditioned response (CR). Consider Mary, whose siblings locked her in closets, and now is terrified of elevators (Carson, Butcher & Mineka, 2000).
Social phobias are an irrational fear of being publicly humiliated or embarassed. A common example is urinating in a public bathroom, especially if you are male. Individuals with social phobias try to avoid situations where unfamiliar people will evaluate them.
Approximately 12% of people will develop a specific phobia during their lives, with rates slightly higher among women. (Kessler et al., 2012).
Why is this phobia so prevalent? It may be explained by the preparedness theory of phobias, which maintains that people are instinctively predisposed to towards certain fears. For example, we are more easily conditioned to fear facial expressions of anger than other types of expressions. (Woody & Nosen, Phobias2008).
From neuroscience: abnormalities in the neurotransmitters serotonin and dopamine are more common in individuals who report phobias than they are among people who do not. (Stein, 1998). These same individuals also abnormally high levels of activity in the amygdala.
People with social phobias report more distressing symptoms, but they are no more physiologically aroused than normals, if the task is social evaluation. This suggests that the social phobia may be due to the person's subjective experience of the situation (Jamieson, Nock & Mendes, 2013).
Again we see the need for phenomenological assessment. Most studies find that people with phobias are no more likely than people without to recall personal experiences with the feared object that provided the basis for classical conditioning. (Craske, 1999).
Panic Disorder is characterized by the sudden occurrence of multiple psychological and physiological symptoms that contribute to a feeling of stark terror. Such symptoms are: shortness of breath; heart palpitations; sweating; dizziness; depersonalization (a feeling of being detached from one's body); or de-realization (a feeling that the external world is strange and unreal); a fear that one is going crazy; a fear that one is about to die. It is difficult to diagnose. (Katon, 1994).
Agoraphobia is a specific phobia involving a fear of public places.
Statistically, panic attacks are fairly common; a third of Canadians may experience one each year, during a period of intense stress. (Telch, Lucas, & Nelson, 1989). Women are twice as likely to develop a panic disorder (Stats Can., 2013).
Family studies suggest some hereditary component, with 30 to 40% of the variance in liability for developing panic disorder attributed to genetic influence. (Hettema, Neale, & Kendler, 2001).
Generalized Anxiety Disorder (GAD) is characterized by unrelenting worries that are not focused on any particular threat, and is accompanied by three or more symptoms: restlessness, fatigue, concentration problems, irritability, muscle tensions, and sleep disturbance.
This is accompanied by a sense of loss of control that erodes self-confidence, making it difficult to make simple decisions.
Approximately 1 in 20 Canadians suffer from GAD at least once in their lives. (CPA 2012); women experience this more than men, 8% to 5%. Identical twin studies of GAD are rare,but identical twins have a higher concordance rate than fraternal twins. Biological explanations of GAD suggest a neurotransmitter imbalance of GABA; although a wide variety of drugs (Valium, Prozac) seem to help the symptoms. Social factors are important. GAD is more likely in large cities, among people who have low incomes, especially women. (Strickland, 1991). Psychologically, unpredictable traumatic experiences in childhood increase the risk of developing GAD.
Obsessive-Compulsive Disorder features repetitive, intrusive thoughts (obsessions) and ritualistic behaviours (compulsions) designed to fend off those thoughts. OCD must significantly interfere with an individual's functioning.
Note: how many horror movies have a character who is intruded upon by a demon, and then must conduct a ritual to drive that demon away?
Anxiety plays a role in this disorder because obsessions typically produce anxiety, leading to irrational and excessive rituals. Thought suppression can backfire, increasing the frequency and intensity of the obsessions.
Again, how many horror movies have this exact pattern, especially in the first act?
In Canada, only 1 in 50 will develop full-blown OCD. (CPA, 2012) Similar to anxiety disorder, rates are higher among women.
Among those with OCD, the most common obsessions are: (1) checking 79%; (2) ordering 57%; moral concerns 43%; contamination (26%). (Ruscio et al., 2010).
OCD focuses on potentially real problems, placing it in the same evolutionary category of preparedness theory as a phobia. (Szechtman & Woody, 2006).
In terms of neurology, one hypothesis is heightened neural activity in the caudate nucleus, a portion of the basal ganglia known to be involved in intentional actions. (Rappoport, 1990).
Drugs than increase the activity of the neurotransmitter serotonin can inhibit the activity of the caudate nucleus and relieve some of the symptoms of OCD. (Hansen et al., 2002) This overactivity might be an effect of the disorder, not a cause.
Subjects in successful psychotherapy show a corresponding reduction in the activity of the caudate nucleus. (Baxter et al., 1992)
Post Traumatic Stress Disorder is characterized by chronic physiological arousal, recurrent unwanted thoughts or images of the trauma, and avoidance of things that recall the traumatic event. Many soldiers return from battle with combat experiences of PTSD, including flashbacks of battle, exaggerated anxiety and startle reactions, also medical conditions that do not arise from physical injury (such as paralysis or chronic fatigue). These are normal responses to horrifying events, and usually subside with time. At one time in their lives, 1 in 10 Canadians will suffer from PTSD (Kessler, Berglund, et al., 2005)
Research using brain imaging techniques to examine brain structure and function have identified important neural correlates of PTSD: heightened activity in the amygdala; decreased activity in the medial prefrontal cortex; a smaller sized hippocampus.
The last condition asks a question: “Correlation or Causation?”One important study suggests that although a group of combat veterans with PTSD showed reduced hippocampal volume, so did the identical (monozygotic) twins of those men, even though the twins have never had any combat exposure, or developed PTSD. This suggests that the veteran's reduced hippocampal volumes were not caused by the combat exposure; instead both these veterans and their identical twin brothers might have had a smaller hippocampus to begin with, a preexisting condition that made them susceptible to developing PTSD after combat. (Gilbertson et al., 2002)Depression and Bipolar Disorders
Mood disorders are characterized by disturbances in mood; their predominant feature is often sadness, but can also be irrational happiness or mania.
A major depressive (unipolar) disorder is characterized by a severely depressed mood and/or inability to experience pleasure that lasts 2 or more weeks and is accompanied by feelings or worthlessness, lethargy, sleep and appetite disturbances. In a related condition called dysthymia, the same cognitive and bodily problems as in depression are present, but they are less severe and last longer, persisting for at least 2 years.
Men are more likely to suffer from dysthymia, denying negative emotions, and engaging in self-distracting activities, such as drinking alcohol. When both types occurs, the resulting condition is a double depression, defined as a moderately depressed mood that persists for at least 2 years and is punctuated by periods of major depression.
Seasonal Affective Disorder (SAD) is not merely having the blues because of the weather. It appears to be due to reduced exposure to light in the winter months (Westrin & Lam, 2007).
On average, major depression lasts about 12 weeks (Eaton et al., 2008) Without treatment, approximately 80% of individuals will experience at least one recurrence of the disorder. (Mueller et al., 1999) Compared with people who have a single episode, individuals with recurrent depression have more severe symptoms, higher rates of depression in their families, more suicide attempts, and higher rates of divorce. (Merikangas, Wicki, & Angst, 1994).
Similar to anxiety disorders, rates of depression are much higher in women than in men (22% to 14%). (Kessler et al., 2012).
Are the causes social or biological? Women have lower incomes, and are more likely to live in poverty, but estrogen, androgen, and progesterone influence depression; some women experience postpartum depression (after childbirth) due to changing hormone balance.
There is also the social factor: women are more likely to face their depression and seek help, leading to higher rates of diagnosis.(Nolen-Hoekseam, 2008).
Biological factors for depression:
Heritability rates vary as a function of severity. A relatively large study of twins found that concordance rates for severe major depression (three or more episodes) were quite high (59%) for identical twins and 30% for fraternal twins (Bertelsen, Harvald & Hauge, 1977). In contrast, concordance rates for less severe major depression (less than 3 episodes) fell to 33% for identical twins and 14% for fraternal twins. Heritability rates for dysthymia are low and inconsistent. (Plomin et al., 1997)
Note: could this last statistic support why men are so little inclined to report depression?
Depletion of norepinephrine and serotonin was considered as the cause of major depression, leading to pharmacological solutions such as Prozac or Zoloft, which increase the availability of serotonin to the brain (SSRI). A biochemical model of depression must account for all evidence, as of today, it cannot account for increases of norepinephrine activity among depressed inviduals (Thase & Howland, 1995). Also antidepressants take at least two weeks to relieve depressive symptoms, and are not always effective in some cases.
A newer approach: diathesis-stress finds that stressful life events are much more likely to lead to depression among those with a certain genetic vulnerability (Caspi et al., 2003).
Note we discussed this in class as an epigenetic trigger.
A recent meta-analysis (a quantitative synthesis of 24 brain imaging studies) found that when viewing negative stimuli such as words or images people suffering from depression showed both increased activity in regions associated with processing emotional information and decreased activity in areas involved with cognitive control. (Hamilton et al., 2012).
Structure Activity in Depression
A Amygdala=Increased
B Dorsal ACC=Increased
C Insula & superior temporal gyrus=Increased
D DLPFC=Decreased
E Caudate=Decreased
Cognitive Model of Depression. A negative, pessimistic view of the world is remarkably stable and consistent and begins in childhood with experiences that create a pattern of negative self-thoughts. (Gibb, Alloy & Tierney, 2001). Abramson, Seligman and Teasdale (1978) have proposed a helplessness theory, part of a cognitive model of depression which maintains that individuals who are prone to depression automatically attribute negative experiences to internal causes, stable, and global. For example: “It's my fault; I can't change; I'll always do this everywhere I go, and to everyone”.
You can fill in the addiction or other self-destructive behaviour yourself.
Bipolar Disorder
Bipolar disorder is a condition characterized by cycles of abnormal, persistent high mood (mania) and low mood (depression). In about two thirds of people with bipolar disorder, manic episodes immediately precede or immediately follow depressive episodes (Whybrow, 1997). The depressive phase of bipolar is often indistinguishable from major depression (Johnson, Cueller, & Miller, 2009). To meet DSM5 standards, the manic phase must last at least one week, and exhibit elevated, expansive, or irritable moods. Other prominent symptoms include grandiosity, decreased need for sleep, talkativeness, racing thoughts, distractability, and reckless behaviour such as compulsive gambling, sexual indiscretion, unrestrained spending sprees.
Psychotic behaviors such as hallucinations and delusions may be present, so the condition may be misdiagnosed as schizophrenia. Bipolar disorder is typically a recurrent condition, with approximately 90% of afflicted people suffering from several episodes over a lifetime. (Coryell et al., 1995) About 10% of the afflicted have rapid-cycling bipolar disorder, characterized by at least four mood episodes (either manic or depressive) every year, making this form of the disorder especially difficult to treat. (Post et al., 2008). Rapid cycling is more common among women than men, and may be precipitated by antidepressant drugs. (Whybrow, 1997).
Biological And Epigenetic Factors Of the various mental disorders, bipolar disorder has the highest rates of heritability, with concordance from 40 to 70% for identical twins and 10% for fraternal twins. (Craddock & Jones, 1999). It is likely polygenic arising from an interaction of multiple genes.
There are also pleiotropic effects, one gene influences another's susceptibility to multiple disorders (a domino effect). The genes that are common in bipolar disorder and schizophrenia comprise the abilities to filter unnecessary information and recognition memory, as well as imbalances of dopamine and serotonin transmission. (Huang et al.,2010)
Epigenetic triggers explain that genetic risk factors influence the development of bipolar and related disorders. Studies examining monozygotic twin pairs (identical twins who share 100% of their DNA) in which one develops bipolar disorder or schizophrenia and one does not, reveal significant epigenetic differences between the two, with decreased methylation of genetic locations know to be important in brain development. (Labrie, Pai, & Petronis, 2012).
Note: DNA methylation of the gene turns it off.
Schizophrenia and Other Psychotic Disorders
Schizophrenia is a psychotic (break from reality) disorder characterized by profound disruption of basic psychological processes, a distorted perception of reality, altered or blunted emotion, and disturbances in thought, motivation, and behavior.
The positive symptoms are: hallucinations; delusions; disorganized speech; and grossly disorganized behavior. The last symptom can be explained as specific motor disturbance including strange movements, rigid posturing, odd mannerisms, bizarre grimacing, or hyperactivity. The last can also include catatonia, a marked decrease in all movement or an increase in muscular rigidity.
Such individuals may resist being moved, or become completely unresponsive and unaware of their surroundings, a catatonic stupor.
The negative symptoms are deficits or disruptions to normal emotions and behaviour, including social withdrawal, apathy, and poverty of speech. Especially important here is negative affect, or a lack of emotion, demonstrated by flat monotonal speech and a lack of facial expression.
The cognitive symptoms are deficits in executive functioning such as decision making, focus of attention, and working memory. These make it difficult for the schizophrenic to maintain friendships or hold down a job. (Green et al., 2000).
Schizophrenia occurs in about 1% of the population (Jablensky, 1997) and is slightly more common in men than in women.
Biologic and Genetic Factors The average concordance rate of the disorder is higher (48%) for identical twins than for fraternal twins (17%) which suggests a genetic component (Torrey et al., 1994).
Environmental factors, such as prenatal environments also effect concordance rates. (Jurewicz, Owen, & O'Donovan, 2001).
The dopamine hypothesis suggests that schizophrenia involves an excess of dopamine activity. This hypothesis is used to explain why amphetamines (which increase dopamine levels) can exacerbate symptoms of schizophrenia. (Iverson, 2006). This was a strong argument, until it was demonstrated that dopamine-blocking drugs (major tranquilizers) do not get the favourable response expected, and even then that beneficial response may take weeks (although the drugs act immediately).
More likely the disorder may involve a complex interaction among a host of different biochemicals.(Risman et al., 2008)
Neuroanatomy demonstrates enlarged ventricles (hollow areas in the brain filled with cerebrospinal fluid) in schizophrenic patients. In some individuals (primarily those with chronic, negative symptoms) the ventricles are abnormally enlarged, suggesting a loss of brain tissue mass that could arise from an anomaly in prenatal development. (Arnold et al., 1998).
The enlarged ventrical explanation is not complete, because, for example, some types of antipsychotic medications prescribed in schizophrenia can cause the ventricles to enlarge.
The advent of MRI scans and high-powered computers has allowed researchers to create 3d models of normal and schizophrenic brains, especially adolescent ones. (Thompson et al., 2001) They detected progressive tissue loss in the parietal lobe , eventually encompassing much of the brain, and of a much higher order of magnitude than normal brain tissue lost in adolescence.
Psychological and social factors in schizophrenia suggest that family environment plays a role in the development and recovery from the condition. Tienari et al., (2004) found that children (whose biological mothers had schizophrenia) and were adopted into disturbed families (extreme conflict, lack of communication, and/or chaotic relationships) were at increased risk for the likelihood of developing the disorder. This outcome was not found among children who were also reared in disturbed families but whose biological mothers did not have schizophrenia.
Childhood and Adolescent Developmental Disorders
Autism Spectrum Disorder is a condition beginning in early childhood in which a person shows persistent communication deficits as well as restricted and repetitive patterns of behaviors, interests, or activities.
At present, the rate of ASD diagnosis is 60 in 10,000 children, which may be a result of better screening. (Newschaffer et al., 2007). Boys have higher rates of ASD than girls by a ration of 4:1. ASD is currently viewed as a heterogeneous set of traits that cluster together in some families (heritability estimates for ASD can be 90%, leaving some children with a few mild ASD traits and other with a more severe form of the disorder. (Geschwind, 2009).
Some people with ASD have unique strengths, such as remarkable abilities to perceive or remember details, or to master symbol systems such as mathematics or music. (Happe & Vital, 2009).
One current model suggest that ASD is an impaired capacity for empathizing (know the mental states of others) , combined with a superior ability for systematizing (understanding the rules that organize the structure and function of objects (BaronCohen & Belmonte, 2005).
Brain imaging studies show that ASD people have comparatively decreased activity in regions associated with understanding the minds of others and greater activation in regions related to basic object perception (Sigman, Spencer & Wang, 2006).
Attention Deficit / Hyperactivity Disorder is characterized by persistent patterns of severe problems with inattention and/or hyperactivity or impulsiveness that causes significant impairments in functioning. Approximately 10% of boys and 4% of girls meet criterian for ADHD (Polanczyk et al., 2007). The DSM5 requires that the symptoms be present for the age of 12 in order to meet the criteria for this disorder. One study of 500 people with ADHD found that about half had a C average or lower, and about one third were in special classes. (Bierdermann et al., 2006).
It is now thought that the disorder persists into adulthood; approximately 4% of adults meet the criteria for ADHD. Adults with this disorder are likely to be male, divorced, and unemployed. Most do not receive treatment for their condition. (Kessler, Alder, et al., 2006).
Genetic studies suggest that there is a strong biological influence and estimate the heritability of ADHD is 76% (Faraone et al., 2005)
Brain imaging studies of those with ADHD have smaller brain volumes (Castellanos et al., 2002) as well as structural and functional abnormalities in fronto-subcortical networks associated with attention and behavioural inhibition. (Makris et al., 2009).
Conduct Disorder is a persistent pattern of deviant behavior involving aggression to people or animals, destruction of property, deceitfulness, theft and serious rule violations. In the U.S. approximately 9% of people report a lifetime history of conduct disorder: 12% of boys and 7% of girls. (Nock et al., 2006).
There are a wide range of confounding causes: risk factors for the disorder include maternal smoking during pregnancy, affiliation with deviant peer groups, and the presence of deficits in executive functioning (such as impulsiveness).(Boden et al., 2010). Conduct disorder tends to co-occur with other disorders characterized by problems with decision making and impulsiveness, such as ADHD, substance abuse, and antisocial personality.
Personality Disorder Focus: Anti-Social and Suicidal
Antisocial personality disorder (APD) is a pervasive pattern of disgregard for and violation of the rights of others that begins in childhood or early adolescence and continues into adulthood. Adults with an APD diagnosis typically have a history of conduct disorder before the age of 15. There are seven diagnostic signs: illegal behavior; deception; impulsivity; physical aggression; recklessness; irresponsibility; and an lack of remorse for wrongdoing. About 3.6% of the population had APD, and the rate of occurrence in men is 3 times that of women. (Grant et al., 2004).
Both the early onset of conduct problems and the lack of success in treatment suggest that career criminality has an internal cause (Lykken, 1995). Evidence of brain abnormalities in people with APD is also accumulating. For example, criminal psychopaths who are shown negative emotional words such as hate or corpse exhibit less activity in the amygdala and hippocampus than do noncriminals. (Kiehl et al., 2001) These two brain areas are involved in fear conditioning , so their relative inactivity suggests the APD's are less sensitive to fear than are othe people.
Suicidal Behaviour is intentional self-inflicted death. In Canada, it is the second most common cause of death for people aged 15 to 34, claiming 18 out of every 100,000 males, and 5 out of every 100,000 females aged 10 and older. (Stats Can, 2014).
Demographics are important; 75% of suicides occur among men, and immigrants are only 1/2 as likely as those born in Canada. (Malenfant, 2004). Rates of suicide among Canadian Aboriginals are much higher: 56 out of 100,000 males; 12 out of 100,000 females. (SIM, 2013).
A suicide attempt has to be considered separately. Here a person engages in potentially harmful behaviour with some intention of dying, occurring much more frequently than suicide deaths. Only 1/3 of those who think about suicide actually go on to make a suicide attempt. Women experience suicidal thoughts and nonfatal suicide attempts at significantly higher rates than do men. (Nock et al., 2008)
In the United States, suicidal thoughts and behaviours are virtually nonexistent before age 10, but then increase dramatically from 12 to 18 years, levelling off before early adulthood. (Nock at al., 2013)
More than 90% of people who die by suicide have a mental disorder; the experience of a significant negative life event during childhood (physical and/or sexual assualt); the presence of severe medical problems.
(Nock, Borges & Ono, 2012).