Covid brain can cause brain to shrink, new study finds

It may explain symptoms such as 'brain fog'

According to a recent study, the phenomena referred to as covid brain may not only be real but new data also suggests that it may cause people's brain to shrink. As per the research carried out on 785 UK Biobank participants and published in the peer-reviewed multidisciplinary science journal, Nature, three key long-term effects were observed: "(i) greater reduction in grey matter thickness and tissue-contrast in the orbitofrontal cortex and parahippocampal gyrus, (ii) greater changes in markers of tissue damage in regions functionally-connected to the primary olfactory cortex, and (iii) greater reduction in global brain size." Observing subjects aged between 51 and 81 who underwent two brain scans - 401 of which suffered a coronavirus infection between their first and second scan - on average, infected showed "cognitive decline between the two timepoints". [caption id="attachment_321846" align="alignnone" width="634"]

Credit: UK Biobank - The perceived change between first and second MRI scans[/caption] It was found that even after mild infections, the overall size of the participants' brain had shrunk slightly, with less grey matter in the regions related to smell and memory, specifically - hence people reporting side effects such as 'brain fog' and prolonged symptoms like loss of their olfactory senses. The study's lead author Professor Gwenaelle Douaud and her team are still trying to determine how great an impact these lasting changes have on those affected and whether or not they are reversible. However, given what they already know about the brain's physiology, they remain positive. "We need to bear in mind that the brain is really plastic - by that we mean it can heal itself - so there is a really good chance that, over time, the harmful effects of infection will ease," says Douaud; it is also unclear as to whether the associated cells die off and if variants cause these results. As you can see, those tested experienced anywhere between 0.2 and 2 per cent shrinkage but the subject of what larger impacts a covid infection can have on the brain remains one that is still very much being investigated.