Even Mild COVID Cases May Cause Damage in the Brain, Study Suggests

As the United States approaches nearly 80 million Covid-19 cases since the start of the pandemic, it's likely that you, or someone you know, has had it at some point. And while we know the symptoms' impact in the short-term, the virus' lasting effects still remain somewhat of a mystery.

However, a recent study conducted by researchers at the University of Oxford reveals a new understanding of the effects of Covid-19 on our bodies. The findings, published in Nature, suggest that even a mild case of Covid-19 can speed up the aging process of the brain.

The Research

The researchers examined brain scans of 401 individuals who'd been infected with Covid-19 between March 2020 and May 2021. The scans were taken before infection and about 4.5 months following infection.

When compared to brain scans from 384 individuals who hadn't contracted Covid-19, those who'd had the virus showed greater loss of gray matter and damage to brain tissue. These differences were found mainly in the areas of the brain that deal with our sense of smell.

The scans also revealed that overall brain size decreased in participants who'd been infected, as well. These findings were more prominent in older participants.

"They also showed greater decline in their mental abilities to perform complex tasks, and this mental worsening was partly related to these brain abnormalities," said lead study author Gwenaëlle Douaud, PhD, in a statement. "All these negative effects were more marked at older ages. A key question for future brain imaging studies is to see if this brain tissue damage resolves over the longer term."

The data used for the study was collected from a government health database, the UK Biobank. Participants, whose ages fell between 51-81, underwent two brain scans about 38 months apart. The scan taken prior to infection has special significance, said senior study author Stephen Smith in a release.

"The fact that we have the pre-infection scan helps us distinguish brain changes related to the infection from differences that may have pre-existed in their brains," Smith said.

A Better Understanding

"This study highlights that even non-brain infections and inflammation, in general, can have lasting deleterious effects in the body including brain injury, atrophy, and dementia," says neurologist Santosh Kesari, MD, PhD, regional medical director for the Research Clinical Institute of Providence Southern California.

While previous research has linked Covid-19 to inflammation as a potential cause for damage to the brain, Naomi Allen, chief scientist at the UK Biobank, noted in a release that this particular study is extremely rare in demonstrating a "before vs. after" depiction of the brain in relation to Covid-19.

"Collecting a second set of multi-organ imaging scans from some people who had been infected with SARS-CoV-2 and from others who had not been infected has generated a unique resource to enable scientists to understand how the virus affects internal organs," Allen said,

As a normal part of the aging process, our brains lose a little gray matter each year. And while study participants showed slightly greater loss in gray matter, researchers are still unsure as to whether that could impact function and quality of life.

While these findings are important, the long-term effects of Covid-19 are still unknown and further research is necessary.