The brain before and after Covid-19

 People who have even a mild case of Covid-19 may have accelerated aging of the brain and other changes to it, according to a new study.The study, 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.

"We were quite surprised to see clear differences in the brain even with mild infection," lead author Gwenaëlle Douaud, an associate professor of neurosciences at the University of Oxford, told CNN in an email.

Douaud and her colleagues evaluated brain imaging from 401 people who had Covid-19 between March 2020 and April 2021, both before infection and an average of 4½ months after infection. They compared the results with brain imaging of 384 uninfected people similar in age, socioeconomics and risk factors such as blood pressure and obesity. Of the 401 infected people, 15 had been hospitalized.