An NIH study has found damage and inflammation of the blood vessels in the brains of patients with COVID-19, but no infection

Press release

Wednesday, December 30, 2020

The results of a study of 19 dead patients suggest that brain damage is a byproduct of a patient’s illness.

In an in-depth study of how COVID-19 affects a patient’s brain, researchers at the National Institutes of Health consistently detected the distinctive features of damage caused by thinning and loss of cerebral blood vessels. in tissue samples from patients who died shortly after contracting the disease. In addition, they saw no signs of SARS-CoV-2 in the tissue samples, suggesting that the damage was not caused by a direct viral attack on the brain. The results were published as correspondence in the New England Journal of Medicine.

“We found that the brains of patients who contract SARS-CoV-2 infection may be susceptible to damage to microvascular blood vessels. Our results suggest that this may be caused by the body’s inflammatory response to the virus,” Avindra said. Nath, MD, clinical director of the NIH’s National Institute of Neurological Disorders and Treatments (NINDS) and lead author of the study. “We hope these results will help physicians understand the full spectrum of problems patients may suffer, so we can get better treatments.”

Although COVID-19 is primarily a respiratory disease, patients often experience neurological problems, including headaches, delirium, cognitive dysfunction, dizziness, fatigue, and loss of smell. The disease can also cause patients to suffer from stroke and other neuropathologies.

Several studies have shown that the disease can cause inflammation and damage to blood vessels. In one of these studies, researchers found evidence of small amounts of SARS-CoV-2 in the brains of some patients. However, scientists are still trying to understand how the disease affects the brain.

In this study, researchers conducted an in-depth examination of brain tissue samples from 19 patients who had died after experiencing COVID-19 between March and July 2020. Samples from 16 of the patients were provided by the main forensic doctor’s office. New York, while the other 3 cases were provided by the pathology department of the University of Iowa College of Medicine, Iowa City. Patients died at a wide range of ages, from 5 to 73 years. They died within hours or two months of being notified of symptoms. Many patients had one or more risk factors, such as diabetes, obesity, and cardiovascular disease. Eight of the patients were found dead at home or in public settings. Three more patients collapsed and died suddenly.

Initially, the researchers used a special high-power magnetic resonance imaging (MRI) scanner, which is 4 to 10 times more sensitive than most MRI scanners, to examine samples of olfactory bulbs and brain stem of each patient. These regions are thought to be highly susceptible to COVID-19. Olfactory bulbs control our sense of smell while the brainstem controls respiration and heart rate. Explorations revealed that both regions had abundant bright spots, called hyperintensities, which often indicate inflammation, and dark spots, called hypointensities, which represent bleeding.

The researchers used the scans as a guide to examine the spots closer to the microscope. They found that the bright spots contained blood vessels that were thinner than normal and sometimes filtered blood proteins, such as fibrinogen, into the brain. This seemed to trigger an immune reaction. The spots were surrounded by blood T cells and the brain’s own immune cells called microglia. In contrast, the dark spots contained clotted and leaking blood vessels, but no immune response.

“It simply came to our notice then. Originally, we expected to see damage caused by lack of oxygen. Instead, we saw multifocal areas of damage that are often associated with stroke and neuroinflammatory diseases, ”Dr. Nath said.

Finally, the researchers saw no signs of infection in brain tissue samples although they used several methods to detect genetic material or SARS-CoV-2 proteins.

“So far, our results suggest that the damage we’ve seen may not have been caused by the SARS-CoV-2 virus that directly infects the brain,” Dr. Nath said. “In the future, we plan to study how COVID-19 harms the blood vessels in the brain and whether this produces some of the short- and long-term symptoms we see in patients.”

This study was supported by the NIH Intramural Research Program of the National Institute of Neurological Disorders and Treatments (NS003130) and an NIH grant (NS109284).

NINDS (https://www.ninds.nih.gov) is the leading national funder of research on the brain and nervous system. The mission of NINDS is to seek fundamental knowledge about the brain and nervous system and to use this knowledge to reduce the burden of neurological diseases.

Regarding the National Institute on Aging (NIA): NIA leads the U.S. federal government’s effort to conduct and support research on aging and the health and well-being of older people. Learn more about age-related cognitive change and neurodegenerative diseases through the NIA’s Center for Reference and Education on Dementia (ADEAR) website. For information on a wide range of aged topics, visit the NIA’s main website and stay connected.

Regarding the National Institutes of Health (NIH):
NIH, the country’s medical research agency, includes 27 institutes and centers and is a component of the U.S. Department of Health and Human Services. NIH is the leading federal agency that conducts and supports basic, clinical, and translational medical research, and investigates the causes, treatments, and cures for common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

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