Covid can cause brain gray matter loss in recovered patients, Oxford researchers say – ThePrint

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New Delhi: British scientists have found evidence in brain images that show that mild Covid-19 infection causes significant loss of gray matter in several parts of the brain related to various functions such as memory formation, emotional response and basic functions vital for survival, such as heart rate, respiration and digestion.

The team at the University of Oxford in the UK noted that while there is strong evidence that Covid can affect the brain, the vast majority of brain imaging studies so far have focused on cases. moderate to severe. Such studies are often performed on hospitalized patients.

However, it is not known whether the impact of Covid-19 can be detected in the milder cases.

The team wanted to determine whether the effect of mild Covid on the brain can reveal a possible mechanism for the spread of the disease.

UK Biobank – a large-scale biomedical database with in-depth genetic and health information from half a million UK participants – had scanned more than 40,000 participants before the start of the Covid-19 pandemic.

This allowed the researchers to invite hundreds of previously imaged participants again in 2021 for a second imaging visit.

“We studied the effects of the disease on the brain using multimodal data from 782 participants in UK Biobank’s COVID-19 re-imaging study, with 394 participants who tested positive for SARS infection. CoV-2 between their two scans “, the team writes in their study Posted on medRxiv which has not yet been peer reviewed.

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Gray matter loss

Researchers compared brain scans before and after Covid infection to determine brain changes between these 394 Covid-19 patients and 388 controls (participants who did not contract Covid).

Researchers identified significant effects of Covid in the brain with loss of gray matter in the left parahippocampal gyrus, left lateral orbitofrontal cortex, and left insula.

The left parahippocampal gyrus is associated with memory, the orbitofrontal cortex (OFC) is involved in the cognitive decision-making process, and the insula is related to basic survival needs such as heart rate, digestion, respiratory rate , urination, sexual arousal, and fight-or-flight response.

The team also compared 15 Covid-19 patients who had been hospitalized with those who were not. Although the results were not significant, the team found a higher amount of gray matter loss in hospitalized patients from the cingulate cortex, central nucleus of the amygdala, and horn of the hippocampus.

The cingulate cortex is associated with emotional responses, the amygdala forms emotional memories, and the hippocampal ammonia horn is essential for memory formation.

The researchers noted that unlike several studies that look at brain images only after Covid infection, this particular research was able to look at “before” and “after” brain images of patients, allowing scientists to rule out any other cause. gray matter. loss.

However, because this study is observational, the researchers said that the causation of the disease cannot be claimed with absolute certainty – that is, the loss of material does not have to be gray was caused by infection with Covid-19.

Other undetermined factors may be causing the loss, which require further studies, the researchers said.

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