October 29, 2020 -- The coronavirus can affect brain functioning and cause mental decline equivalent to the brain aging by about 10 years, according to a new study published on the preprint server MedRxiv. The study hasn’t yet been peer-reviewed.

Even those who have recovered from COVID-19 may face “chronic cognitive consequences,” they found. In the worst cases, the mental decline was similar to a drop in 8.5 IQ points.

“The results align with the ‘brain fog’ reported by many people who, even months after recovery, say they are unable to concentrate on work or focus how they did before,” Adam Hampshire, the lead research and a doctor at Imperial College London, told The Times of London.

The research analyzed cognitive tests for more than 84,000 people in the UK who had recovered from confirmed or suspected COVID-19. They saw that recovered patients performed worse on cognitive tests in multiple areas than would be expected for their age and other demographics. The tests included questions that measured problem-solving abilities, working memory, selective attention and emotional processing.

They found that the cognitive declines led to a “substantial effect size” and were greater based on the severity of COVID-19 symptoms. The shift was particularly evident among those who were hospitalized, they found, but it also appeared among those who weren’t hospitalized.

Those who were hospitalized and placed on a ventilator had an average score that equated to a 10-year decline in brain performance, the authors wrote. This is similar to an 8.5-point difference on a classic IQ test, they added. The difference was most noticeable for problem-solving tasks and visual selective attention, they wrote, which has been observed in previous studies of hospitalized patients with respiratory disease.

“Consequently, the observation of post-infection deficits in the subgroup who were put on a ventilator was not surprising,” the research team wrote. “Conversely, the deficits in cases who were not put on a ventilator, particularly those who remained at home, was unexpected.”

The findings are a “clarion call” for more research, the team wrote. A limitation of the study, for instance, is that the researchers weren’t able to do before-and-after cognitive test scores.

“The cognitive function of the participants was not known pre-COVID, and the results also do not reflect long-term recovery — so any effects on cognition may be short-term,” Joanna Wardlaw, a professor of applied neuroimaging at Edinburgh University, told Reuters.

The research is “intriguing but inclusive,” Derek Hill, a professor of medical imaging science at University College London, told Reuters.

“As researchers seek to better understand the long-term impact of COVID, it will be important to further investigate the extent to which cognition is impacted in the weeks and months after the infection and whether permanent damage to brain function results in some people,” he said.

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MedRxiv, “Cognitive deficits in people who have recovered from COVID-19 relative to controls: An N=84,285 online study.”

The Times, “Coronavirus could age the brain by 10 years or cause IQ to fall.”

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