Scientists have discovered that even a mild case of COVID-19 might inflict damage on your brain.
On average, middle-aged and older adults who’d been sick with COVID showed signs of tissue shrinkage in brain areas related to the sense of smell, the researchers reported. They also tended to have more trouble completing complex mental tasks, when compared to people with no history of COVID-19 — an effect that was most striking among the oldest adults.
Experts said the findings strengthen evidence that even mild COVID-19 may cause detectable deficits in the brain.
That’s because the researchers had access to brain scans taken from people both before and after they’d been infected. That helps distinguish brain changes associated with COVID-19 from any abnormalities that may have already been there.
“We still cannot be sure with 100% certainty that there is a causal effect of the infection,” lead researcher Gwenaelle Douaud, a professor at the University of Oxford, in the United Kingdom says.
“But,” she adds, “we can disentangle the effects that we observe from differences that may have pre-existed in the brain of the participants before they became infected with SARS-CoV-2.”
What does this mean?
There are still key questions, however. What caused the brain changes? And what, precisely, do they mean?
Recent research has estimated that up to 30% of people with COVID-19 develop “long-haul” symptoms that plague them well after they’ve beaten the infection. The list includes fatigue, headaches, shortness of breath, dulled sense of smell and taste, and problems with memory and concentration that have been dubbed “brain fog.”
Experts still do not know what causes “long COVID,” or why it can strike after a mild infection. One theory pins the blame on overactivation of the immune system, leading to widespread inflammation in the body.
Dr. Joanna Hellmuth is a neurologist at the University of California, San Francisco, who is studying post-COVID symptoms. She says it’s not clear what may have caused the brain changes seen in this study.
But Hellmuth says the fact that tissue shrinkage occurred in smell-related areas points to one possibility: lack of