Catching Covid could cause shrinkage and tissue damage in relation to smell and mental capacities, a new study has found. This is the first crucial study to asses brain scans of people before and after they had Covid.
It comes after the biggest study of genetics of Covid-19 found 16 new genetic variants linked with severe illness and labelled a number of existing drugs that could be reused to help patients from getting seriously ill.
Both these studies have highlighted the biological mechanisms that develop the disease.
In the latest study, researchers at the University of Oxford studied 785 people aged between 51 and 81 who accepted brain scans prior and during the pandemic as part of the UK Biobank study. Over a half of them tested positive for Covid between the two scans.
Those who tested positive for Covid had more brain shrinkage and more grey matter shrinkage, notably in areas linked to smell, compared with 384 uninfected control subjects.
People who had Covid lost an additional 1.8% of the parahippocampal gyrus, which is a key region of smell. They also lost an additional 0.8% of the cerebellum, which aids motor skills and balance, compared with control subjects.
People who caught the disease also usually scored lower on a mental skills test than those who were uninfected. The lower scores were linked with a larger loss of brain tissues in the parts of the cerebellum involved in mental ability.
The results were more pronounced in older people and those hospitalised by Covid-19, but they were still visible in others whose infections were asymptomatic or mild.
“The brain is plastic, which means that it can re-organise and heal itself to some extent, even in older people,” said Prof Gwenaëlle Douaud at the University of Oxford.
More studies are needed to asses whether these brain changes are long-lasting or partially reversible.