An analysis of brain scans from people once infected with COVID-19 suggested a consistent pattern in loss of grey matter over time, researchers say.

"Our findings thus consistently relate to loss of grey matter in limbic cortical areas directly linked to the primary olfactory and gustatory system," or areas in the brain related to the perception of smell and taste, authors wrote.

Researchers said the three areas revealing a "significant loss" in thickness and volume of grey matter among COVID-19 patients was the "parahippocampal gyrus, the lateral orbitofrontal cortex, and the superior insula," later adding that the "strongest deleterious effects of COVID-19 could be seen predominantly in the left hemisphere.".

Results from the comparison of hospitalized patients "were not significant," but authors noted "comparatively similar" findings to the larger group of coronavirus patients, "with, in addition, a greater loss of grey matter in the cingulate cortex, central nucleus of the amygdala and hippocampal cornu ammonis.".

"By using automated, objective and quantitative methods, we were able to uncover a consistent spatial pattern of loss of grey matter in limbic brain regions forming an olfactory and gustatory network