People who have been infected with coronavirus could face triple the rate of degeneration in some areas of the brain compared with those who have not, a groundbreaking study has found
University of Oxford researchers examined brain scans of more than 400 people between the ages of 51 and 81 before and after catching the disease.
Results showed that in olfactory-related regions of the brain, responsible for smell, brain volume shrunk by an average of 0.7% compared to a control group who had not contracted the disease.
The human brain naturally shrinks with age – however, the extent of the shrinking was far more significant among those who had caught the disease in the study.
A person of middle age would normally expect to lose about 0.2% volume in that area per year, while an older person could expect to see a 0.3% decrease.
Covid patients partaking in the study had an average of four months between the two scans, indicating that the virus' impact on those regions is fast-working and significant.
And that wasn't the only impact the virus had on Covid survivors – the participants were also asked to complete cognitive tests, which on average took longer for those who had had the virus than those who hadn't.
The Covid survivors also achieved worse scores on the tests.
To verify the results, the researchers carried out an analysis of the brains of pneumonia patients and found no similar changes – demonstrating that the difference in cognition was likely due to Covid.
The breakthrough study might explain why many report suffering brain fog and other neurological issues long after overcoming the initial Covid infection.
The scientists behind the research noted a more pronounced reduction in brain volume among older participants in the study, and the 15 who had been hospitalised with Covid.
However, the declines were still more significant in those who had mild or moderate Covid or were asymptomatic compared to their peers who had not contracted the virus at all.
Professor Gewnaelle Douaud, a neuroscientist who led the study, told MailOnline : "Despite the infection being mild in 96% of our participants, we saw a greater loss of grey matter volume and greater tissue damage in the infected participants.
"All these negative effects were more marked at older ages."
The study was published in weekly international research journal Nature, and is thought to be the first in the world to investigate large-scale changes in the brain after a Covid infection.
Nottingham University neuroimaging expert Dr Rebecca Dewey, who was not involved in the study, said the research was 'compelling'.
She said: "If the findings were based on imaging data alone, I would say that we have much less reason to worry about this as the brain is so plastic that it is likely to compensate in the absence of any conditions preventing this.
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"These sorts of changes are seen after many forms of disease onslaught, and even that of healthy ageing.
"The key difference shown here is that they appear to be happening faster than with ageing alone."
However, not everybody in the scientific community was convinced.
Professor Alan Carson, a neuropsychiatrist at the University of Edinburgh, said the changes were 'very modest'.
"Such changes can be caused by a simple change in mental experience," he explained.
"I am very concerned by the alarming use of language in the report with terms such as 'neurodegenerative'."
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