New research today seeks to bring us closer to understanding how covid-19 can cause brain damage. The study suggests that, although viral infection may not directly reach the brain in most cases, it can trigger the type of destructive inflammation seen in other neurological conditions, such as stroke.
The research was conducted by scientists from the United States government at the National Institutes of Health and was 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 MRIs, as well as looking at brain tissue under a microscope. The age of these patients ranged from 5 to 73 years, some with health problems such as diabetes and cardiovascular diseases.
The researchers were unable to find any trace of the virus in these samples, indicating that it had not infected the brain. But they found clogged, diluted and leaking blood vessels. Near some of these vessels, they also found signs of inflammation, such as higher levels of immune cells in the brain called microglia. In all, the findings indicate that these patients and others like them are developing a defective immune response that attacks blood vessels in the brain – a response that is triggered by coronavirus infection.
“We were completely surprised. We originally expected to see damage from lack of oxygen. Instead, we saw multifocal areas of damage that are generally associated with strokes and neuroinflammatory diseases, ”said senior study author Avindra Nath, clinical director of the NIH National Institute of Neurological Diseases and Strokes, in a statement released by NIH.
G / O Media can receive a commission
Some studies have found evidences that the virus can directly invade the brain and parts of the body connected to the brain, particularly the olfactory bulb that helps us process the smell. Infection in these areas may still be responsible for certain symptoms seen with covid-19, such as loss of smell, 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 harm the body, including the brain. Other research found that covid-19 may increase risk or worsen inflammation-related health conditions, such as blows and heart damage.
“While it is quite possible that we may have lost any brain infection with the virus, we think it is unlikely, as we use several techniques to detect the virus,” Nath told Gizmodo via email. “These other studies found a very low number of virus copies in the brain, so it is unlikely to be the main mechanism of pathology.”
Although all of the patients in this study died, the findings may also help explain why some survivors continue to experience persistent complications, even after the infection is cleared. Often, these complications appear to be neurological and include difficulty focusing, memory problems and other symptoms known collectively as brain fog.
“Even if the patients died suddenly, they did not die from an apparent neurological disease,” explained Nath. The people included in this survey are probably not inconsistent, he said, so “the findings here may be relevant for long-term survivors as well.”