Whether changes are irreversible not yet known, says study
Even a mild infection of Covid-19 can negatively tinker the brain and thinking, scientists have found in a study that highlights the illness’ alarming impact on mental function.
However, in a bid to not scare the Covid-survivors about their mental status, the researchers simultaneously clarified that they are yet to investigate whether the changes are reversible.
The researchers identified Covid-associated brain damage months after infection, including in the region linked to smell. They pointed out that shrinkage in size could be equivalent to as much as a decade of normal aging. The changes were linked to cognitive decline in the study, which was published Monday in the journal Nature.
The study is believed to be the first involving people who underwent brain scans both before they contracted Covid and months after. Neurological experts who were not involved in the research said it was valuable and unique, but they cautioned that the implications of the changes were unclear and did not necessarily suggest that people might have lasting damage or that the changes might profoundly affect thinking, memory or other functions.
The study, involving people aged 51 to 81, found shrinkage and tissue damage primarily in brain areas related to sense of smell. Some of those areas are also involved in other brain functions, the researchers said.
The study involved 785 participants in UK Biobank, a repository of medical and other data from about half a million people in Britain. The participants each underwent two brain scans roughly three years apart, plus some basic cognitive testing. In between their two scans, 401 participants tested positive for the coronavirus, all infected between March 2020 and April 2021.
The other 384 participants formed a control group because they had not been infected with the coronavirus and had similar characteristics to the infected patients in areas like age, sex, medical history and socioeconomic status.
With normal ageing, people lose a tiny fraction of gray matter each year. For example, in regions related to memory, the typical annual loss is between 0.2 per cent and 0.3 per cent, the researchers said.
But Covid patients in the study — who underwent their second brain scan an average of four and a half months after their infection — lost more than non-infected participants, experiencing between 0.2 per cent and 2 per cent additional gray matter loss in different brain regions over the three years between scans. They also lost more overall brain volume and showed more tissue damage in certain areas.