Home >Science >Health >Covid may be more damaging to the brain than we thought

Covid-19’s impact on our health has been discussed a lot—it can cause weakness, respiratory issues, fever, sore throat, rashes etc. However, its impact on the brain has been spoken about only in terms of headache, brain fog, or a loss of smell and taste. But a recent study reveals more.

How much did we know so far?

Covid’s impact on brain has a much wider scope than previously believed. When the pandemic began, one of the distinct signs that health experts noticed was the loss of smell and taste, often even before or without signs of respiratory distress. Other neurological symptoms were soon noticed as well, such as headache, nausea and vomiting, and extreme fatigue. Dr. Kiran T. Thakur, a neurologist at Columbia University Irving Medical Center in New York, had told The Washington Post that “viruses that invade the brain are tough to eradicate because  a  barrier protects the  brain  from  the  rest  of  the  body."

What does the new study reveal?

Last week, medRxiv released a pre-print version (which has not been peer-reviewed yet) of a research paper showing that people suffering  from covid-19 had significant losses of grey matter surrounding the olfactory and gustatory system. Imaging-derived phenotypes of the participants revealed loss of grey matter in regions associated with memory in the left hemisphere and the temporal pole of the right hemisphere. It compared data from pre-infection imaging to data taken post-infection, letting it avoid the risk of pre-existing conditions which could have been misinterpreted as an outcome of the disease.

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Why are the new findings worrying?

Volume change in grey matter is only one of the brain conditions caused by covid. Authors of the study also believe that the brain volume loss lasts much longer than the actual infection. Besides, unlike what was previously believed, it can be noticed even in those with mild cases of covid-19, though, the loss of grey matter was seen to increase with the severity of the infection.

How was the study conducted?

The study used data gathered by UK Biobank, a long-term research and data centre that collects in-depth genetic and health details. It scanned 40,000 participants before the start of the pandemic. This year, it called back hundreds of those who had been scanned for a second imaging visit. Researchers then used multimodal data from 782 participants from the re-imaging study. Over 390 of them tested positive between the scans. They  then  compared  structural  and functional brain scans to compare longitudinal brain changes.

Has any other virus had a similar effect?

Sars-Cov-2, which causes covid-19, is not the only one which has impacted our brains. Many other infections similarly affect the nervous system. For example, Dr Gabriel A. de Erausquin, a professor of neurology at The University of Texas Health Science Center at San Antonio, has said, “Since the flu pandemic of 1917 and 1918, many of the flu-like diseases have been associated with brain disorders." Measles, HIV, herpes, polio all can lead to fatal outcomes. However, these are all infections.

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