According to a study published in the journal Nature that is believed to be the largest of its kind. It is found that those who had Covid-19 have had a greater loss of gray matter and abnormalities in their brain tissues compared to people who didn’t have Covid-19. Much of the changes were noted in the area of the brain that is related to the sense of smell.

Lead author Gwenaëlle Douaud, an associate professor of neurosciences at the University of Oxford said that it was surprising to see the clear difference in the brain even after a mild infection. After comparing 401 people who had Covid-19 between March 2020 and April 2021, both before infection and 4.5 months after infection. The brain imaging of 384 uninfected people was compared that were similar in age with risk factors including obesity and blood pressure. Out of 401 infected people, 15 had been hospitalized.

There were 785 participants that were aged between 51 and 81 who were part of the UK Biobank, which was an ongoing government health database of 500,000 people that had begun in 2012.

According to Douaud, it was normal for people to lose 0.2 per cent to about 0.3 per cent of gray matter every year in the brain area as they age, but a study found that people who were infected by Covid-19 lost an additional 0.2 per cent to 2 per cent of tissue compared to those who were not infected.

In additional imaging, people were tested for their cognitive and executive function using the Trail Making Test which is a tool used to help in detecting cognitive impairments associated with dementia to test a person’s brain function and processing speed. The researchers went on to find that people who had the greatest brain tissue loss also performed the worst on this exam.