Researchers have examined brain changes in people who had been mildly infected with SARS-CoV-2 (COVID-19), including identifying damage to the areas of the brain related to processing smell.
Over 700 people recruited from UK Biobank, underwent brain imaging twice over the course of 38 months to examine changes in their brain over time. 401 cases had tested positive for Covid-19 between the two scans. They also completed a number of cognitive tasks to assess whether thinking and information processing skills had been affected. A number of studies to date have already identified changes in cognitive processes such as memory following moderate or severe Covid infection.
The study found a reduction of grey matter thickness in the orbitofrontal cortex and parahippocampal gyrus, and tissue damage to regions connected to the olfactory cortex, an area of the brain responsible for processing smell. The overall brain size of those infected with Covid-19 was also found to be reduced. These brain changes were identified, on average, 4.5 months after infection. Participants also performed worse on the cognitive tasks than those who were not infected.
The authors of the study conclude that further research is needed to understand whether these changes are long-term or can be partially reversed over time.
The research, published in Nature, is available to view at www.nature.com/articles/s41586-022-04569-5.
A loss or change in sense of smell has been one of the earliest reported effects of Covid-19 infection. It is also a common effect of many types of brain injury. For tips on coping with a loss of sense of smell, see our information factsheet below.
Reference: Douaud, G., Lee, S., Alfaro-Almagro, F., Arthofer, C., Wang, C., McCarthy, P., Lange, F., Andersson, J.L.R., Griffanti, L., Duff, E., Jbabdi, S., Taschler, B., Keating, P., Winkler, A.M., Collins, R., Matthews, P.M., Allen, N., Miller, K.L., Nichols, T.E., & Smith, S.M. (2022). SARS-Cov-2 is associated with changes in brain structure in UK Biobank. Nature, 604, 697-707.
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