Study suggests COVID aftereffect: Permanent loss of smell or taste

Grey matter loss in brains is usually associated with ageing, but a new study from the UK Biobank study shows that COVID-19 too could be a contributor.

The study shows significant loss of grey matter in the brains of people who recovered from the infection, which experts attribute to damage caused to brain tissues. The conclusions were drawn basis follow-up scans (before after infection) of 394 COVID survivors and 388 healthy volunteers. Most COVID survivors studied had mild to moderate infection.
Grey matter is a major component of the central nervous system which processes information. It includes regions of the brain involved in muscle control and sensory perception such as seeing and hearing, memory, emotions, speech, decision making, and self-control. A change in grey matter composition directly impacts communication skills and brain cells.

An earlier study had suggested that COVID may result in stroke or dementia-like symptoms.

The UK study suggests people affected by COVID reported significant loss of gray matter in regions of the brain that respond to smell, taste, cognitive function and memory. The scan also revealed damage to those areas of the brain that evoke emotional reactions.  The researchers, however, said more study is required to find out if patients who recovered will struggle to remember emotion-evoking events.

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Scientists also want to find out if the loss of grey matter is a direct consequence of virus entering the brain or its other implications.

“The converging longitudinal analyses revealed a significant, deleterious impact of COVID-19 on the olfactory and gustatory cortical systems, with a more pronounced reduction of grey matter thickness and volume in the left parahippocampal gyrus, the left superior (dorsal) insula and the left lateral orbitofrontal cortex in the Covid patients,” the study said.

None of these changes were observed in the 388 healthy volunteers, who had not been infected.