Thousands of coronavirus patients have reported covid19, brain fog. In fact, in a study done in france, 34 of patients experienced memory loss from the coronavirus and 27 of patients actually had concentration problems after the recovery. Well, this was just from a phone questionnaire. This begs to question: could these cognitive symptoms be something we should be worried about? Patients have come together and shared their stories, and one patient actually states that they lost the memory of a 12-day trip.
They took to france just three weeks before contracting the virus. Another lady was unable to identify her car in a parking lot and she was very confused that she looked around for her toyota, not remembering what her car looked like or what type of car she drove at all. Another nurse practitioner that suffered from covert 19 as well stated that she forgot how to do routine lab tests and often has to ask colleagues for help dealing with different terms that used to come to her like this.
So this is called Covid - 19 brain fog. It deals with memory, loss, confusion, dizziness grasping for words and difficulty concentrating why this might be happening could be because of the persistent immune response that our bodies exhibit to the covid-19 virus. If we have inflammation of blood vessels and cells lining vessels in our brains, then we can have these cognitive effects. Also, the release of cytokines with the cytokine storm could be triggering the cognitive effects as well.
So what are cytokines? Are these immune system molecules that are communication molecules released into the body to cause inflammation and cause a response that can help fight foreign invaders or fight infection in the body, but for the brain cytokines can cause too much inflammation, which can lead to cognitive impairments. Another proposition by one neurologist was that perhaps tiny strokes are happening which could be leading to these spouts of dizziness or to these white static moments in somebody's day.
Now, we've actually seen some brain fog in the flu with the influenza virus. We have seen that the immune response sometimes does trigger this cloudiness and, if you're, ever getting over a cold or if you're, ever sick, maybe a couple days before you come down with the flu and you get your fever. You might feel this fogginess and inability to focus it's not all in your head. The immune system is actually coming into play and our body working towards attacking the foreign invader actually leads to impacts on our brain.
This is actually known as psychoneuroimmunology. That's the interaction of psychology neuroscience and immunology. So what is pni or psychoneuroimmunology? I is interactions between the central nervous system and the immune system. So if we want to talk about the central nervous system, the central nervous system includes nerves, hormones and neurotransmitters. The immune system includes organs throughout our bodies that help fight off disease, and they do so by releasing things called cytokines, which help promote inflammation and attack.
Foreign invaders cytokines can also communicate with the nervous system in a way that might be detrimental to cognition. So let's talk about these cytokines cytokines tend to be pro-inflammatory in response to an infection. Now some studies have shown that the immune system and the nervous system are actually linked through evolution and activating the immune system has been shown to influence neurotransmitters, particularly monoamines and glutamate.
So if we talk about glutamate, glutamate is one of the number one excitatory neurotransmitters in the nervous system. What happens when we have an immune response? Is we see failed clearance of glutamine? We see increased release of glutamine and this increased release actually leads to loss of synaptic fidelity. So, let's break down what this means. Glutamate basically, is just a little messenger molecule when our nerves, fire they release glutamate to tell the next nerve hey.
This is what's happening. So if we have an activated immune system, our body actually starts releasing more glutamate and weirdly enough. Our body is unable to clear the glutamate as quickly as usual, so usually a nerve will release the messenger and then other cells will clean up the glutamate and get it out of the way. But this is no longer happening and when the body is bombarded with glutamate, all of a sudden, it's not going to the right neurons it's now spreading and we lose the fidelity which is the connection from one nerve to another.
Now the message is getting more dispersed throughout the brain. We also see impacts on dopamine dopamine is a motivational neurotransmitter, and we see with the immune response. We have decreased motivation and we can also have issues with movement. Dopamine is also important in parkinson's disease, where we have a loss of dopamine, and then we have a loss of movement. So, with this decreased dopamine that we see with the immune response, we also see decreased movement and motor slowing.
Perhaps this can be why it's harder to move when you're sick, but also your body is probably really tired, fighting off the disease. Now we also see the immune system being related to neurodegeneration neurodegeneration. With the immune system, we would have things like excessive pruning pruning, like pruning a bush. When you cut the bush and you make it look nice and pretty it actually happens in our brain with synapses.
So we have all these branches coming off of the nerve and the nerve communicates to a bunch of other nerves. But some connections are unnecessary, so we prune them with neurodegeneration. We would have excessive pruning, and this happens in things like schizophrenia, but also with aging as well, when we see disorders like alzheimer's disease, as we get older, the microglial cells that we talked about earlier actually become hyper, responsive and pro-inflammatory.
So we have more inflammation as we age and more responsiveness. Interestingly, in models of alzheimer's studies have been done where we ablated microglial cells, and this actually decreased the amount of spine loss and cognitive impairment in the mice. Now, why is this happening? Well, because there's not excessive pruning going on, but when it comes to the balance we need pruning. Still, if you didn't have microglial cells to keep the brain in order, then we would have too many connections and it would be hard to function just the same as if you don't have enough connections.
So there's an important balance but again when the immune system is affected, this actually affects our brain, which can affect our cognition and our thinking now. Another aspect of the immune system in the central nervous system is the choroid plexus, the choroid plexus filters blood. Now blood doesn't go into the brain. Blood goes through the choroid plexus different proteins get filtered out of it.
What the brain needs stays in and it becomes known as cerebral spinal fluid. Now, when we have inflammatory signals going through the body we actually upregulate, inflammatory cytokines, so those signaling molecules from the immune system increase when we have some sort of infection. These include things like interleukin, beta, tumor, necrosis factor, alpha interleukin-6, and when that happens, we have up-regulation of adhesion molecules and down regulation of tight junctions.
So tight junctions keep cells together, and this is very important at the blood-brain barrier, because we have a barrier of cells bound really tight together with those tight junctions, and if we start to break them down, we break down the blood-brain barrier a little now this tends To be a very quick reaction and there's only a small amount of immune cells that can get through the brain during the response that lasts for typically about 24 to 48 hours, so some immune cells can enter the brain during inflammation because of this reduction in tight Junctions, so it seems that peripheral immunity or immunity throughout our body seems to be influencing brain homeostasis and brain function.
One very interesting study actually took lipopolysaccharide lipopolysaccharide in the human body mimics the effect of an infection, so it triggers an immune response and a cytokine storm. We've talked about the cytokine storm in several of our other cobin 19 articles. So if you want to check those out feel free to check them out as well they're, also in the description. Basically, what happened after lipopolysaccharide injections was that there was a reduction in ltp or long-term potentiation.
Long-Term potentiation is very important for learning and getting memories to stick in the brain. Basically, what happens with long-term potentiation? Is we form synapses to create memories or to create neural networks that represent memories in the brain? So what could be happening is if we have reductions in ltp. Memory is harder to form which might have been what happened in the case of the gentleman that forgot his trip to paris, long-term potentiation might have been reduced and the memory just might have never been encoded, so he had a little bout of retrograde amnesia.
So all in all, the conclusion is that patients are having these symptoms and it's not all in their head. One patient actually said that people have said that to them and I think we need to get over the stigma about mental health issues, and this could be considered mental health. When you have fogginess and one patient even said she didn't know what to do, because how can you explain these symptoms to somebody? How can you say that you're, forgetting common names of items like a toothbrush, she had to ask her friend? What's that thing called you used to clean your teeth with these are common everyday items that we would be shocked if we couldn't find the name of it in our head.
So it seems that this is all happening because of some sort of immune response to the virus that is lasting longer than our usual responses. This could be because maybe it's a new virus and our body is trying to develop an adaptive immune response and create new antigens for the virus. But there could be other reasons as well that we don't know if you're interested in this and why it's happening. And if you're interested in the interactions of the brain and the immune system, I suggest you look into psychoneuroimmunology and if you have any questions, leave them down below make sure you like comment and subscribe, leave any suggestions.
You have for future articles and we'll see you next week on neurosci q for another week's episode. If you have any theories about why this might be happening or if you've read any interesting papers that tie into this concept, leave them down below i'd love to check them out, make sure you like comment and subscribe to the blog. So we can keep creating more articles for your educational purposes and your viewing pleasure thanks for reading i'll, see you next week on neurosciq