Press release
Wednesday, December 30, 2020
The results of a study of 19 deceased patients suggest that brain damage is a by-product of the 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 identified the marks of damage caused by narrowing and leaking cerebral blood vessels in tissue samples from patients who died shortly afterwards. 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 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 microvascular damage to 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 of the National Institute of Neurological Diseases and Stroke (NINDS) at the NIH and senior author of the study. “We hope that these results will help doctors understand the full spectrum 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 impairment, dizziness, fatigue and loss of smell. The disease can also cause strokes and other neuropathologies.
Several studies have shown that the disease can cause inflammation and damage to blood vessels. In one of these studies, the 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, the researchers performed an in-depth examination of brain tissue samples from 19 patients who died after trying COVID-19 between March and July 2020. Samples from 16 of the patients were provided by the Chief Medical Examiner’s Office in 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 in a wide range of ages, from 5 to 73 years. They died within a few hours to two months after reporting the 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 settings. Another three patients passed out and died suddenly.
Initially, the researchers used a special high-powered magnetic resonance imaging (MRI) scanner that is 4 to 10 times more sensitive than most MRI machines, to examine samples from each patient’s olfactory bulbs and brain stem. These regions are considered highly susceptible to COVID-19. The olfactory bulbs control our sense of smell, while the brain stem controls our breathing and heart rate. The scans revealed that both regions had an abundance of bright spots, called hyperintensities, which usually indicate inflammation, and dark spots, called hypointensities, which represent bleeding.
The researchers then used the scans as a guide to examine the points more closely under the microscope. They found that the bright spots contained blood vessels that were thinner than normal and sometimes leaked 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.
“We were completely surprised. We originally expected to see damage from lack of oxygen. Instead, we saw multifocal areas of damage that are often associated with strokes and neuroinflammatory diseases, ”said Dr. Nath.
Finally, the researchers saw no signs of infection in the brain tissue samples, although they used several methods to detect SARS-CoV-2 genetic material or proteins.
“So far, our results suggest that the damage we saw may not have been caused by the SARS-CoV-2 virus that directly infects the brain,” said Dr. Nath. “In the future, we plan to study how COVID-19 damages the blood vessels in the brain and whether it produces some of the short and long-term symptoms that we see in patients.”
This study was funded by the NIH Intramural Research Program of the National Institute of Neurological Disorders and Stroke (NS003130) and an NIH grant (NS109284).
NINDS (https://www.ninds.nih.gov) is the main national funder of research on the brain and nervous system. NINDS ‘mission is to seek fundamental knowledge about the brain and nervous system and use that knowledge to reduce the burden of neurological diseases.
About the National Aging Institute (NIA): The NIA leads the United States federal government’s efforts to conduct and support research on aging, health and well-being of the elderly. Learn more about age-related cognitive changes and neurodegenerative diseases through the website of the NIA and Alzheimer’s Dementia Reference and Education Center (ADEAR). For information on a wide range of aging topics, visit the main NIA website and stay connected.
About the National Institutes of Health (NIH):
NIH, the country’s medical research agency, includes 27 institutes and centers and is a component of the United States Department of Health and Human Services. NIH is the leading federal agency that conducts and supports basic, clinical and translational medical research, and is investigating 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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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 lesion in the brains of patients with COVID-19. New England Journal of Medicine, December 30, 2020 DOI: 10.1056 / NEJMc2033369.