Research suggests that people’s intelligence decreases when infected with the coronavirus, with severe infections having the greatest decline in IQ.
Brits who avoided the disease typically performed best on intelligence tests, while those who ended up in hospital performed worst.
However, it is thought that even people with only mild illnesses are likely to have impaired cognitive abilities.
Scientists at Imperial College London analyzed data from more than 112,000 volunteers who were tested for coronavirus during the pandemic.
The analysis found that people who were admitted to intensive care with COVID-19 had, on average, about nine points lower IQ scores on tests than those who avoided infection.
Those who reported having had a long-lasting coronavirus infection (with persistent symptoms such as “brain fog”) scored six points lower, and those who had a milder infection had two points lower.
Professor Adam Hampshire, lead author of the study published in the medical journal The Lancet, tried to match people as closely as possible by considering other factors when comparing groups.
Further testing revealed long-lasting effects on cognitive function, even in people infected more than a year ago.
While the original Covid strain was associated with a greater decline in IQ, there was only a small difference in Omicron. Vaccination also appears to have a preventive effect.
Professor Hampshire said the implications of the figures were “very frightening”.
Participants were enrolled in Imperial College’s React study. Dr Tackett said the study did not compare the same people before and after infection, so the results should be interpreted with caution.
Professor Benedict Michael, director of the Infectious Neuroscience Laboratory at the University of Liverpool, said there was “clearly a very severely affected group”.
But he added: “We have yet to see convincing evidence that the majority of the population has been knocked back by X IQ points.”
Another study, which analyzed brain scans taken before and after the pandemic, suggests that coronavirus infection can affect people even if they are not hospitalized.
Professor Michael said the virus did not infect the brain, but appeared to be a secondary result of infection in other parts of the body, and may have acted on blood vessels, reducing oxygen flow. Ta. Researchers say it remains unclear whether the brains of coronavirus patients fully recover.
