How Coronavirus and COVID-19 Affects The Brain

Brain Affects of Coronavirus and COVID-19

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Coronavirus Affects The Brain

We know that coronavirus (SARS CoV-2) has been found in the brain and we know it affects the brain.

A study published January 19, 2021 demonstrates a role of direct infection from SARS CoV-2 in the brain of the mice being studied. This new study found that intranasal infection of K18-hACE2 mice (see the end of the article for an explanation as to what these mice are) by SARS-CoV-2 causes severe neurological disease and death. This data demonstrates that the brain is the major target of SARS-CoV-2 infection in K18-hACE2 mice after introduction of the virus into the nasal passages, and that brain infection is associated with immune cell infiltration, inflammation and cell death.

What We Have Seen in The Neurological System of Humans

Although most individuals showing symptoms of COVID-19 syndrome demonstrate respiratory symptoms as a primary issue, there are other symptoms that are less commonly displayed and the central nervous system is one of the body organs that may also be affected. The symptoms indicating an infection of the central nervous system run the gambit of headache, loss of taste and smell, ataxia (act drunk, slurred speech, stumbling, falling, incoordination, eye movement abnormalities, tremors, heart problems), meningitis, cognitive dysfunction, memory loss, seizures and impaired consciousness. Some people (about 1/3 of those presenting with symptoms – remember a significant but unknown amount of people also never have symptoms – so this is not 1/3 of the population with COVID-19, but 1/3 of those who present with symptoms) have also experienced long-term lingering neurological symptoms. Other coronaviruses are also known to present with neurological symptoms.

The ACE2 Receptor

I have written in other articles about the angiotensin-converting enzyme 2 (ACE2) and we know that these receptors are in multiple body organs including the brain where the receptors are found in cells such as the neurons, glial cells and astrocytes. These receptors have been found in various parts of the brain including the amygdala, cerebral cortex and brainstem, with the highest amounts found in the pons and medulla oblongata in the brainstem that contain the medullary respiratory centers of the brain.

Coronavirus Found in Human Brains On Autopsies

Some of the autopsy reports have shown SARS-CoV-2 in brain tissue of people who have died with COVID-19. This would indicate that SARS-CoV-2 can infect the brain in humans. However, no one has yet studied COVID-19 in regard to how the virus infects the brain, the involvement of inflammation and the neurological complications that take place. So, this study was undertaken in mice to get some idea as to how COVID-19 might affect mice if introduced intranasally.

The Study Results

The mice were inoculated through the nose. There was subsequent viral infection of the central nervous system (brain) with high levels of virus replication and fatal disease. The inflammatory response was associated with production of cytokines/chemokines. Their data indicated that following infection by the intranasal route, the virus entered the brain by traversing the cribriform plate and infecting neuronal processes located near the site of intranasal inoculation. The peak amount of virus in the brains of these mice were approximately 1000 times higher than the peak amount in the lungs, suggesting the SARS-CoV-2 has the ability to replicate in large numbers in the brain. The relative upregulation of cytokine and chemokine mRNAs was approximately 10 to 50 times higher in the brain compared to the lungs, strongly suggesting that extensive neuroinflammation contributed to clinical disease in these mice.

How This Relates To Loss of Smell and Taste

Data from this research may also explain the loss of smell and taste noted by some individuals with COVID-19. The study indicates that SARS-CoV-2 can infect cells within the nasal turbinate, eye and olfactory bulb in intranasally infected K18-hACE2 mice. The detection of virus replication in these tissues suggests that SARS-CoV-2 can access the brain by first infecting the olfactory bulb and then spreading into the brain by infecting the connecting brain neuron axons. This hypothesis is consistent with previous studies that neurotropic coronaviruses infect olfactory neurons and are transmitted to the brain via axonal transportation. The authors point out that many viruses, such as Herpes simplex virus-1, Nipah virus, rabies virus, Hendra virus and influenza A virus, have also been shown to enter the CNS via olfactory sensory neurons. Another route by which a virus can gain access to the brain is via the disruption of the blood–brain barrier (BBB). (similar to disruption of the intestinal barrier that many call “leaky gut”) However, the researchers said they did not find any virus in the serum of the infected mice at any time after the infection, suggesting a limited role of BBB disruption in SARS-CoV-2 invasion of the brain.

The Use of K18-hACE2 transgenic mice

Some of you are asking, "what are K18-hACE2 transgenic mice?"

Mice are often genetically altered to study particular disease processes or drugs. K18-hACE2 transgenic mice express human ACE2. Remember this is the receptor used by The coronavirus SARS-CoV-2 to gain entry into our cells. These K18-hACE2 mice are more susceptible to SARS-CoV-2 and SARS-CoV viruses, making them useful to researchers for studying antiviral therapies to both coronaviruses.

Don't Get Freaked Out Just Yet

We should not all get freaked out thinking we will get an infected brain and die after reading this article. Remember, these mice are genetically altered to become more susceptible to this disease gaining entry into their cells. Additionally, they are mice and we can’t assume similar activities in humans although this is sometimes true. We know that most people have no symptoms or mild symptoms and we have not had enough people displaying neurological symptoms to yet figure out fully what is taking place. So, it is likely this is a small subset of the population. Remember that even herpes simplex can get into the brain and kill a person, yet it happens infrequently. We don't know enough about the effect of the SARS-CoV-2 virus on our central nervous system or how many people are affected by the coronavirus or how severe the symptoms are and to what extent they may linger. Plus, we can do things to support our body's innate healing ability and protective features. All this comes naturally as part of our birth-right (to some genetic degree or another). However, we do have to keep up the maintenance on our particular models or the warranty plan on our bodies becomes null and void.

I would suggest that those people who are inclined to pick their nose, should either stop or they might at least want to scrub their hands and fingernails well before hand, just in case they have touched a door knob or something else that had SARS-CoV-2 on it. Definitely, do wash your hands well when coming home from being out and about in the community. That should be a given for general health any way.

Luckily, we have the ability to support our immune system by eating well, exercising and using additional lifestyle choices to support our immune system. This is vitally important in protecting us from all viruses including coronaviruses.

There is a reason that people who have pre-existing inflammatory correlated diseases are more likely to do poorly with this illness. Many of these diseases can be prevented or their course altered if already present. This is good news for those of us who like to take our health-care into our own hands.

If you want to be healthier and less inflamed, take charge of your health care. Make sure you have a responsive immune system and live a lifestyle that decreases inflammation. What this means usually is the use of dietary changes, exercise, decreasing stress through being mindful and being more resilient. This last part is really important. Resilience of mind and body is important to allow us to change and adapt quickly. It helps keep stress under control and allows us to thrive. Stress is a big driver of inflammation. This can be mental, emotional, spiritual or physical stress. To be more resilient is not just about the body. This means being more accepting of the world at large, seeing the beauty in others, and recognizing that divine spark in all that surrounds you as well as inside of you yourself. Being more loving and inclusive of others is key. Not feeling like the world is a constant threat to be battled, but recognizing what is working well, seeing the gifts around us, and making lemonade from lemons. Here are a few articles that might be of use to you in this endeavour.