How COVID-19 can Affect Human Brain, Research Conducted On Mice

Coronavirus Disease (COVID-19), caused by severe acute respiratory syndrome (SARS-COV-2), broke out from Wuhan, a city in China. However, the virus is spreading worldwide through respiratory droplets or aerosols. This virus is often narrated as a respiratory disease since it strikes the lungs first. As a result, the world observed this disease to halt normal life, restricted the people into their homes, and imposed a travel ban on many countries. This blog discusses research conducted on mice to explain how COVID-19 can affect Human Brain.

More and more cases are being registered with different complications, including vascular, cardiac and neurological, etc. In contrast, neurological complications being more serious. So, Georgia State University administered research on mice.

How Coronavirus Is Affecting Mice

The Journal Viruses published the study in January 2021. The study revealed that on controlled exposure of mice with coronavirus. It found out that in the first few days, the virus was in its log phase in the lungs. But after few days of administration of the virus into the mice through the nasal passage, the brain contained a distinguishing level of the virus than the lungs.

Since lungs and other organs have a good inflammatory response, the virus attack is not possible there. The last phase, known as the declining or death phase on the fifth day after the invasion of the virus into the body. But, not in the brain where it was piling up because of poor brain response to inflammation. Up to this time, the virus population was 1000x more in the brain than in the lungs or any other body organ.

Pathways That Coronavirus Follows To Reach Brain

As the nasal passage provides direct access to the brain than the mouth, the study reveals that the mode of entry of the pathogen is also an important aspect of brain injury. In contrast, other organs can defend against viral invasions. Although the mouth also provides access to the brain, the access through the nasal route is more direct.

The virus entering the nose damages the nasal pathways, gradually moving forward to the olfactory bulb, damaging them and eyes and the remainder of the brain, especially the area surrounding the olfactory lobes.

Initiation Of Immune Response

Although brain cells also showed an inflammatory response to the virus RNA strand, marked by the release of cytokines, interferons, and other proteins needed for immune response. But the number of Cytokines released was more in the brain than they actually released in any other organs.

This high level of cytokines attracts more proteins and inflammatory cells, leading to damage of brain cells and the virus. Gradually, an autoimmune response is generated, leading to worsening health conditions.

Why Its Survival Chances Are High In Brain

Assistant Professor Mukesh Kumar, the lead researcher of the study on mice, explained that, since the survival chances of the virus are high while residing in the brain, most population of the virus is found there because tolerating the immune response in other organs of the body is very hard for the virus. This high population load in the brain leads to the onset or worsening of already present symptoms such as shortness of breath, septic shock, cardiac failure, urinary problems.

So the virus, without practically entering the organs, can make them damage by damaging the part of the brain that controls the organ. This explains the phenomenon that the person who was actually on his path to improvement suddenly collapses as stated by many doctors that the patient was doing fine. So we sent him back home, and within 2-3 days of leaving the hospital, he collapses.

He wrote in his study that while being in a hospital, the patients have minor brain damage that is even harder to diagnose than the major brain damage that can be seen on either MRI or CT Scan of the brain. So the patient leaves the hospital with no brain damage seen on MRI or CT scan, as it’s undetectable at this stage, but further processes to death as there is no mode of screening for the patient at home.

Aftereffects Of Brain Damage

He also explained that the most notable symptom of the disease is the loss of taste and sense of smell. Both of them are neurological rather than being respiratory. The study further revealed that the coronavirus could have lifelong impacts on one’s body depending upon immunity. He also stated the person whose brain is once affected by coronavirus could have many health-related issues in the future—significantly autoimmune diseases such as epilepsy, Parkinson’s disease, multiple sclerosis, and other neurological disorders.

He further said that some people assume that they have recovered from the COVID-19 and are now free to live however they want. I don’t think so that anyone affected by the coronavirus can ever be free of its symptoms as there is always a chance of some health issues due to brain damage.

Neuronal Findings Of COVID-19 In Human Beings

As we all know, the brain is the control center of all the activities, either voluntary or involuntary. Thus, brain damage is a serious concern and can lead to many complications. For example, a study conducted in October 2020 in Chicago exhibited that 82% of admitted patients showed neurological symptoms due to their exposure to the coronavirus.

These symptoms lie in between moderate such as dizziness, headaches to severe such as stroke, seizures. Some of the symptoms generally improved as the body’s white cell army invades and stops the virus attack. However, another study conducted by the Oxford University researchers says that 13% of the people infected by the coronavirus were there with neurological disorders within six months of the infection.

Autopsies Of Human Brain

Traces Of Coronavirus have been proclaimed in several human brain autopsies. According to the research published in the Journal of Virology, the Coronavirus has a strong connection with Multiple Sclerosis. A disease is responsible for the demyelination of neurons. As a result of it, neurological impairment will observe such as:

hyper rigidity
tingling
state of confusion and difficulty in higher intellectual activities
depression and anxiety

Meanwhile, in the research, the scientist revealed a point mutation in the RNA strand of the virus. Furthermore, mutation at OC43 was found consecutively in three patients with Multiple Sclerosis and one control patient. Thus, some researchers believe that the carriage of COVID-19 in human brains is uniform with neuroinvasion.

Another study is supporting the idea of the presence of the virus in neuronal tissues. The research was conducted between March 13 and April 21, 2020. However, the authors published it on October 20, 2020, at The Lancet Neurology. Among the 110 autopsies, 43 found positive for the qRT-PCR test. The test was used to identify and quantify the presence of coronavirus on specimens which in this case were brain tissues.

Among the 39% of people who tested positive for the virus, 37% were women, and 63% were men. The average age all of them lie into was around 76. However, there could be many possibilities regarding the effect of the virus on brain tissues specified with age, gender, etc.

How Coronavirus Impacts Brain

There is not a lot of research material on this genre. But now, several kinds of researches are ruling out the influence of coronavirus on the human brain. The four methods which scientists are considering for the brain damage in coronavirus are as follows:-

Infection
Hyperactive immune response
Increase blood clotting
Disturbance in the body on a larger scale

Signs Of Brain Damage

Normally the human brain, after exposure to the SARS-COV-2, gives some symptoms typical to neurological impairment. These indications may alter from body to body and even completely absent in some people. Some of them may include:-