COVID-19 is tied to deadly brain inflammation in some patients

Images of a human brain scan
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COVID-19 may cause dangerous neurological problems, including delirium, brain inflammation, nerve damage or stroke, according to a new study.

What's more, the study authors reported seeing a concerning increase in patients at their hospital with a rare and sometimes fatal neurological condition called acute disseminated encephalomyelitis (ADEM). All of the patients with ADEM had confirmed or suspected COVID-19, suggesting that the pandemic may be leading to an increase in this condition, the authors said.

The findings add to a growing body of evidence linking COVID-19 to brain effects, and suggest that doctors should be "vigilant and look out for these complications" in COVID-19 patients, study co-senior author Dr. Michael Zandi, a neurologist at the National Hospital for Neurology and Neurosurgery in London, said in a statement.

It's unclear exactly how frequently brain complications occur in COVID-19 patients, but the  study included only hospitalized patients who were referred to the hospital's neurology team, meaning the study likely included some of the most severe cases.

The study authors analyzed information from 43 patients ages 16 to 85 with neurological complications who were treated at National Hospital for Neurology and Neurosurgery, part of the University College London Hospitals NHS Foundation Trust. Of these, 29 had a positive COVID-19 test and the rest were probable or suspected cases of COVID-10 based on symptoms and results from other tests such as chest X-rays and CT scans.

There were 10 cases of so-called transient encephalopathies, or temporary brain dysfunction, with symptoms of delirium, such as confusion and disorientation. One patient had symptoms of psychosis, including visual and auditory hallucinations. Most of these patients eventually made a complete recovery without specific treatments.

Separately, eight patients had strokes, typically due to blood clots. Previously, researchers found that COVID-19 may increase the risk of blood clots. These patients tended to have poor outcomes, with none making a full recovery, and one patient died after their stroke.

Eight additional patients developed nerve damage, often due to Guillain-Barré syndrome, a rare autoimmune response that typically occurs after an infection, such as a respiratory or gastrointestinal infection.

Twelve of the patients developed brain inflammation, and most of these were also diagnosed with ADEM. One of the patients in this group died. Usually, ADEM is seen in children, but the patients with ADEM in this study were all adults. Before the pandemic, the research team typically saw one adult case of ADEM a month at their hospital, but during the pandemic, that increased to one case per week.

The researchers did not find SARS-CoV-2, the virus that causes COVID-19, in samples of patients' cerebrospinal fluid (the fluid around the brain and spinal cord), suggesting that the virus had not directly attacked the brain in these patients. In some of the patients, there was evidence from brain scans (and in one case, a brain biopsy) that suggested that the brain inflammation was caused by an immune system reaction.

"Our study advances understanding of the different ways in which COVID-19 can affect the brain, which will be paramount in the collective effort to support and manage patients in their treatment and recovery," said study co-first author Dr. Rachel Brown, of the University College London Queen Square Institute of Neurology. 

More studies are needed to understand what causes these brain effects and whether they will lead to long-term health problems, the authors concluded. 

Originally published on Live Science.  

Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.