Study finds new evidence of SARS-CoV-2 damaging brain blood vessels
Scientists have found no trace of SARS-CoV-2 in the brains of people with the infection. However, they have observed blood vessel damage caused by the body’s inflammatory response in the post-mortem brains of patients who tested positive for COVID-19, which suggests the virus may indirectly attack the organ.
The scientific advances researchers made this past year have helped tremendously in learning about the new coronavirus that first appeared in Wuhan, China.
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Earlier this year, reports showed that younger adults who contracted the new coronavirus exhibited more neurological symptoms, including mental confusion, headaches, dizziness, uncoordinated muscle movements, seizures, and a rise in the risk of stroke.
These are but a few examples of how much we have learned and how much we are yet to learn in order to fully understand the SARS-CoV-2 virus. Now, new research suggests that the virus may also cause brain vessel injury.
The study was conducted by researchers from the National Institute of Neurological Disorders and Stroke (NINDS) in Bethesda, MD, and other institutions across the United States.
They examined post-mortem brain tissue samples from 16 patients in New York City and from three patients in Iowa City who had died between March and July 2020 and tested positive for COVID-19 before or after death.
Before death, treatment was mainly geared toward respiratory infection, and only two patients exhibited agitated delirium.
The researchers also used MRI images to detect any abnormalities in the brain tissue. This included the olfactory bulb, a brain area involved in the sense of smell, since loss of smell is known to be one of the first symptoms of COVID-19.
Another brain region they examined was the brain stem, which is crucial for human survival. It regulates sleeping and eating habits and controls heart rate and the rate of breathing.
To asses the relevant brain tissues, the researchers used a staining method called immunohistochemistry, which allows the visualization of proteins within cells and tissues.
Of the 19 brain tissue samples, 13 were imaged, and 10 showed brain anomalies. Further analysis showed blood vessel damage.
In nine patients, the presence of lesions suggested they were leaky brain vessel injuries. There were also signs of a leaking blood protein called fibrinogen in the brain. The authors suggest that this is evidence of inflammation that arises from an overreactive immune system fighting infection.
In 10 patients, MRI images showed hypointensities corresponding to congested blood vessels, and an accumulation of fibrinogen around the area.
“Our results suggest that this may be caused by the body’s inflammatory response to the virus,” says Dr. Avindra Nath, clinical director of the NINDS at the National Institutes of Health (NIH) and the senior author of the study.
Interestingly, the SARS-CoV-2 virus was not found in any of the patients’ brain tissue. However, the authors write that there is no way of knowing whether the virus was present at one point:
“It is possible that the virus was cleared by the time of death or that viral copy numbers were below the level of detection by our assays.”
When looking at the spots of injury more closely, the researchers found that immune cells, such as T cells, were present around the brain, further supporting evidence of an inflammatory response in the brain.
“We were completely surprised. Originally, we expected to see damage that is caused by a lack of oxygen,” says Dr. Nath. “Instead, we saw multifocal areas of damage that is usually associated with strokes and neuroinflammatory diseases.”
Because the novel coronavirus was not detected in the brain tissue of the deceased patients, the authors say it is too early to tell whether there is a link between the neurological effects associated with COVID-19 and the blood vessel injuries observed in this study.
“In the future, we plan to study how COVID-19 harms the brain’s blood vessels and whether that produces some of the short- and long-term symptoms we see in patients,” says Dr. Nath.
As scientists continue to investigate all the effects of SARS-CoV-2 infection, it is important to slow the spread of the virus.
The public can do their part in minimizing the risk of transmission by wearing a face mask, practicing social distancing, and staying home whenever possible.
Following these guidelines is essential as vaccination efforts continue to roll out worldwide.
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