Study links even mild COVID-19 infection with changes to brain
published Monday in the journal Nature, is believed to be the largest of its kind. It found that the brains of those who had Covid-19 had a greater loss of gray matter and abnormalities in the brain tissue compared with those who didn't have Covid-19. Many of those changes were in the area of the brain related to the sense of smell.
The 785 participants were between the ages of 51 and 81 and were all part of the UK Biobank, an ongoing government health database of 500,000 people begun in 2012. Although the areas of the brain most affected appear to be related to the olfactory system, Douaud said it wasn't clear why that was the case.
And while the study finds some association between infection and brain function, it's still not clear why. Previous studies have shown people with significant and repeated loss of smell also have an associated loss of gray matter. However, this study did not evaluate whether people actually had a loss of smell.