Can Covid Change The Brain? Here's What Scans Reveal

As per a recent research, scientists found out huge differences in MRI (magnetic resonance imaging) scans before and after catching Covid infection. Even after getting mild disease, the complete size of the brain had shrunk a bit, with less grey matter in the parts around smell and memory. The researchers still do not know if these changes are permanent or temporary but mentioned that the brain can heal. The study was published in the journal Nature. Read on the article further to know about it.

The lead author Professor Gwenaelle Douaud, from the Wellcome Centre for Integrative Neuroimaging, at the University of Oxford, said, "We were looking at essentially mild infection, so to see that we could really see some differences in their brain and how much their brain had changed compared with those who had not been infected was quite a surprise." The UK Biobank project has observed the health of 500,000 people for around 15 years and has data of all recorded scans before the Covid pandemic so it have them a good opportunity to study the long-term health effects of Coronavirus.

The scientists rescanned:

• 401 participants for 4.5 months, on an average, after their infection, 96% of whom had mild infection
• 384 participants who did not have Covid

They found out:

• The overall brain size in infected patients had shrunk between 0.2 and 2%
• There were less grey matters in the olfactory regions, that are related to smell, and areas linked to memory
• Those who had recently recovered from the disease found it harder to perform complex mental challenges

However, the researchers do not know if these changes are reversible or actually matter for overall health and wellbeing. "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," Prof Douaud said. As mentioned earlier, a major loss of grey matter was in the olfactory areas, but it is still unknown whether the virus directly affects this area or cells just die off due to lack of use after people with COVID-19 experience a loss of sense and smell.

It is also not clear if all variants of the virus cause this damage. The brain scans were performed when the original virus and alpha variant were considered and loss of smell and taste was a common symptom. However, the more recent Omicron variant does not see much of this symptom in people. UK Biobank chief scientist Prof Naomi Allen said: "It opens up all sorts of questions that other researchers can follow up about the effect of coronavirus infection on cognitive function, on brain fog and on other areas of the brain - and to really focus research on how best to mitigate that."

Prof David Werring, from the University College London Institute of Neurology, also said that other health-related behaviour could have an impact on the changes seen. "The changes in cognitive function were also subtle and of unclear relevance to day-to-day function," he said. "And these changes are not necessarily seen in every infected individual and may not be relevant for more recent strains," he added.