Mystery behind brain fog in some COVID-19 patients unearthed: Cytokines, not virus, fuels it

New research indicates that COVID-brain may actually be the result of a cytokine storm and the COVID-19 virus may have had no role to play in this development.

By: Jahnavi Sarma | | Updated: February 11, 2021 8:42 am

COVID brain may occur due to the presence of inflammatory molecules in the liquid surrounding the brain and spinal cord, which is called the cerebrospinal fluid.

A December 2020 study published in the journal Nature Neuroscience says that the COVID-19 virus may enter the brain, which is why some patients exhibit cognitive symptoms like brain fog and fatigue. This condition is also referred to as COVID brain by some experts. The most common symptoms of this brain fog are confusion, headaches and loss of short-term memory. Some people may even experience psychosis and seizures. This brain fog may be apparent sometimes weeks after being infected with the virus. Also Read - Gurugram apartment declared containment zone after 20 tested positive for COVID-19

Till now, most experts believed that the COVID-19 virus is responsible for this condition and many researches are going on to identify possible treatment options. But now, new research indicates that COVID-brain may actually be the result of a treatment procedure and the virus may have had no role to play in this development. Also Read - Here's CoWIN 2.0 is different from its previous version

Coming together to help patients

A new study by researchers from Memorial Sloan Kettering suggests that there may be an underlying cause of COVID brain. It may occur due to the presence of inflammatory molecules in the liquid surrounding the brain and spinal cord, which is called the cerebrospinal fluid. The journal Cancer Cell published this study. According to researchers, experts observed severe delirium in many hospitalized COVID-19 patients So, they decided to collaborate with colleagues in neurology, critical care, microbiology, and neuroradiology to learn what was going on and to see how they could better help their patients. Also Read - 'Do not let your guards down': Centre asks states to deal COVID-19 violations firmly

Identifying the culprit

In medical terms, COVID brain is called encephalopathy. This condition is also common in other systemic inflammatory syndromes. It is also a side-effect in patients who are undergoing a kind of immunotherapy called chimeric antibody receptor (CAR) T cell therapy. This is basically a treatment for blood cancer. CAR T cell therapy causes immune cells to release molecules called cytokines, which enable the body to kill the cancer. But cytokines can also seep into the area around the brain and cause inflammation. When researchers first started looking into the causes of COVID brain, they did not know that cytokines were the cause. They suspected that the virus itself was having an effect on the brain.

For the purpose of the study, researcher looked at 18 hospitalized patients with severe neurologic problems. The patients had to undergo brain scans like MRIs and CTs and electroencephalogram (EEG) monitoring, so that researchers could find the cause of their delirium. But when nothing was found in the scans to explain their condition, the researchers suspected that they may find the answers if they look at the cerebrospinal fluid. So researchers devised a test to detect the COVID-19 virus in the fluid. Thirteen of the 18 patients had spinal taps to look for the virus, but it was not found. In the rest of the fluid, researchers saw persistent inflammation and high levels of cytokines, which explained the symptoms they were having.

Understanding the connection between immune and nervous systems

Experts always thought that the nervous system is an immune-privileged organ. It didn’t have any kind of relationship at all with the immune system. But this study proves that this is not the case always. Immune cells are sometimes able to cross the blood-brain barrier.

The inflammatory markers found in the COVID-19 patients were similar, but not identical, to those seen in people who have received CAR T cell therapy. And as with CAR T cell therapy, the neurologic effects are sometimes delayed. The initial inflammatory response with CAR T cell treatment is very similar to the reaction called cytokine storm that’s often reported in people with COVID-19. With both COVID-19 and CAR T cell therapy, the neurologic effects come days or weeks later. In CAR T cell patients, neurologic symptoms are treated with steroids, but doctors don’t yet know the role of anti-inflammatory treatments for people with neurologic symptoms of COVID-19. Many of them are already getting steroids, and it’s possible they may be benefitting.

(With inputs from Agencies)

Published : February 10, 2021 4:30 pm | Updated:February 11, 2021 8:42 am

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