Gwenaëlle Douaud et all.

There is strong evidence of brain-related abnormalities in COVID-191–13. However, it remains unknown whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology.

… Many of our results were found using imaging biomarkers of grey matter thickness or volume, which can be sensitive markers of a neurodegenerative process compared with other imaging modalities …

… the longitudinal differences between the SARS-CoV-2-positive and control groups, although significantly localised in a limbic olfactory and gustatory network, seemed also—at a lower level—to be generalised … This means that there is an overall stronger decrease in grey matter thickness across the entire cortex in the infected participants, but that this effect is particularly dominant in the olfactory system.