The study included 41 people who died at a medical center in New York. The median age of the patients was 74 years, and many of them had comorbidities, including dementia and Parkinson’s disease.
The brains of each deceased were examined by at least two neuropathologists. Using a variety of methods, specialists examined the organ for the presence of viral RNA and proteins, focusing mainly on the olfactory part. Although viral particles were expected to be found in the nasal cavity, they were not found in brain cells.
“At the same time, we saw many pathological changes that could explain why critically ill patients experience confusion, delirium and other severe neurological symptoms, and why people with mild COVID-19 suffer from brain fog for weeks and weeks. months, “- said the authors of the study.
Scientists have named several reasons that can cause neurological damage without brain damage in the presence of COVID-19. The most likely of these is hypoxia (lack of oxygen). When the body tries to get oxygen in a critical situation, various parts of the body and organs are affected. According to the researchers, in each of the studied brains of the deceased were found damage characteristic of hypoxia, which is not surprising with extensive damage to the lungs.
Among other possible causes, scientists named strokes and blood clots, which can block the access of oxygen to the brain and often occur in hospitalized patients with coronavirus.
Scientists have made another important discovery: in all the deceased patients who entered the study, specific immune cells in the brain called microglia were activated. The researchers believe that these immune cells mistakenly attacked neurons, and suggested that it could be due to inflammatory proteins associated with the coronavirus.
“So even without directly infecting brain cells, COVID-19 can cause brain damage,” the study authors wrote. They noted that if neurons are attacked by microglia, their loss is irreversible, which could cause memory problems in the future.