Press release
Wednesday, December 30, 2020
The results of a study of 19 deceased patients suggest that brain damage is a byproduct of the patient’s disease.
In an in-depth study of how COVID-19 affects a patient’s brain, researchers at the National Institutes of Health have consistently identified the hallmarks of damage caused by dilution and leakage of blood vessels in the brain in tissue samples from patients who have 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 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, “said Avindra Nath, MD, clinical director at the National Institute of Neurological Disorders and Stroke (NINDS) and lead author of the study. We hope that these results will help doctors understand the full range of problems that patients may suffer, so that we can come up with 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 sense of smell. The disease can also cause patients to suffer strokes 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 a thorough examination of brain tissue samples from 19 patients who died after suffering from COVID-19 between March and July 2020. Samples from 16 of the patients were provided by the primary care physician’s office. . New York City, while the other 3 cases were provided by the pathology department at 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 a few hours to two months of reporting symptoms. Many patients had one or more risk factors, including diabetes, obesity, and cardiovascular disease. Eight of the patients were found dead at home or in public places. Three other 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 brainstem from each patient. . These regions are considered to be extremely sensitive to COVID-19. The olfactory bulbs control our sense of smell, while the brainstem controls breathing and heart rate. Scans showed that both regions had an abundance of light spots, called hyperintensities, which often indicate inflammation, and dark spots, called hypointensities, which represent bleeding.
The researchers then used the scans as a guide to examine the spots more closely under a microscope. They found that the light spots contained blood vessels that were thinner than normal and sometimes leaked proteins from the blood, such as fibrinogen, into the brain. This seems to trigger an immune reaction. The spots were surrounded by blood T cells and immune cells in the brain called microglia. Instead, the dark spots contained both clotted blood vessels and blood vessels, but did not respond immune.
“It simply came to our notice then. Initially, we expected to see damage caused by lack of oxygen. Instead, we have seen multifocal areas of damage that are usually associated with stroke and neuroinflammatory disease, ”said Dr. Nath.
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.
“To date, our results suggest that the damage we have seen may not have been caused by the SARS-CoV-2 virus that directly infects the brain,” said Dr. Nath. “In the future, we intend to study how COVID-19 damages the blood vessels of the brain and whether they produce some of the short- and long-term symptoms we see in patients.”
This study was supported by the NIH Intramural Research Program at the National Institute for Neurological Disorders and Stroke (NS003130) and an NIH grant (NS109284).
NINDS (https://www.ninds.nih.gov) is the largest national funder of research on the brain and nervous system. The mission of NINDS is to seek basic knowledge about the brain and nervous system and to use this knowledge to reduce the burden of neurological diseases.
About the National Institute for Aging (ANI): ANI is leading the US federal government’s effort to conduct and support research on aging, health and well-being in the elderly. Learn more about age-related cognitive changes and neurodegenerative diseases through the NIA Alzheimer’s Center and Dementias Education and Referral (ADEAR) website. For information on a wide range of aging topics, visit the ANI main website and stay connected.
About the National Institutes of Health (NIH):
NIH, the national medical research agency, includes 27 institutes and centers and is a component of the US 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 of both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.
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Article
Lee MH, Perl DP, Nair G, Li W, Maric D, Murray H, Dodd SJ, Koretsky AP, Watts JA, Cheung V, Masliah E, Horkayne-Szakaly I, Jones R, Stram MN, Moncur J, Hefti M, Folkerth RD, Nath A. Microvascular injury in the brains of patients with COVID-19. New England Journal of Medicine, 30 December 2020 DOI: 10.1056 / NEJMc2033369.