New research conducted today seems to bring us closer to understanding how covid-19 can cause brain damage. The study suggests that while the viral infection does not directly reach the brain in most cases, it can cause the kind of destructive inflammation seen in other neurological conditions, such as a stroke.
The research was conducted by US government scientists at the National Institutes of Health and published in the New England Journal of Medicine. The team studied the brains of 19 people who died after contracting covid-19, using highly sensitive MRI scans and looking at brain tissue under a microscope. These patients ranged in age from 5 to 73 years, and some had pre-existing health problems such as diabetes and cardiovascular disease.
The researchers could not find traces of the virus in these samples, indicating that it had not infected the brain. But they did find clogged, thinned, and leaky blood vessels. They also found signs of inflammation in some of these blood vessels, such as higher levels of immune cells in the brain called microglia. Taken together, the findings indicate that these patients and others like her are developing a faulty immune response that attacks the blood vessels of the brain – a response caused by an infection by the coronavirus.
“We were totally surprised. We originally expected to see damage caused by a lack of oxygen. Instead, we saw multifocal areas of damage commonly associated with strokes and neuro-inflammatory diseases, ”said senior study author Avindra Nath, clinical director of NIH’s National Institute of Neurological Disorders and Stroke, in a statement. released by the NIH.
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Some studies have found proof that the virus can directly enter the brain and parts of the body that are connected to the brain, especially the olfactory bulb that helps us process the smell. Infection of these areas could still be the cause of certain symptoms seen with covid-19, such as loss of odor, at least in some cases. But the new results add to the Substantial evidence that inflammation is a key factor in explaining how covid-19 can cause damage to the body, including the brain. Other research has shown that covid-19 increases the risk of health problems related to inflammation, such as strokes and heart damage.
“While it is entirely possible that we missed an infection of the brain with the virus, we think it is unlikely as we used multiple techniques to detect the virus,” Nath told Gizmodo in an email. “These other papers found very low copy number of viruses in the brain, so it is unlikely to be the main driving mechanism of pathology.”
While the patients in this study all died, the findings may also help explain why some survivors continue to experience persistent complications even after the infection clears. Often these complications appear to be neurological and include difficulty focusing, memory problems, and other symptoms collectively known as brain fog.
“Although the patients died suddenly, they did not die from an apparent neurological condition,” Nath explained. The people involved in this study are likely not outliers, he said, so “the findings here may also be relevant to the long-term survivors.”