Significant Loss of Brain Grey Matter after COVID-19

[Tom.G]

TL;DR

Brain imaging Before and After COVID-19 shows loss of brain grey matter after COVID-19

We identified significant effects of COVID-19 in the brain with a loss of grey matter in the left parahippocampal gyrus, the left lateral orbitofrontal cortex and the left insula. When looking over the entire cortical surface, these results extended to the anterior cingulate cortex, supramarginal gyrus and temporal pole.

https://www.medrxiv.org/content/10.1101/2021.06.11.21258690v1
doi: https://doi.org/10.1101/2021.06.11.21258690

Full PDF (32 pages) at:
https://www.medrxiv.org/content/10.1101/2021.06.11.21258690v1.full.pdf

 

[Ygggdrasil]

After a quickly browsing the paper, I'm somewhat skeptical of the results of the study. The study did comparisons of ~2,000 features from their brain imaging between the two groups, which gives plenty of opportunities to find false positives (potentially an example of p-hacking). Furthermore, the statistically significant differences the paper finds seem quite small compared to normal variation. For example, here are some of the most significant longitudinal group comparison results from Fig 1 of the paper:

https://www.medrxiv.org/content/10.1101/2021.06.11.21258690v1.full.pdf

While these results may be statistically significant differences (at least, assuming they corrected for multiple comparison correction correctly), it's not clear whether these observed differences would be biologically meaningful (i.e. whether the differences are large enough to cause clinically relevant symptoms).