Catching Covid makes people less intelligent, with severe infections lowering IQ the most, a study suggests.
Britons who avoided the disease tended to perform best in intelligence tests, while those who ended up in hospital performed the worst.
But even those who have had only mild illness are likely to have seen their cognitive skills decline, it is thought.
Scientists from Imperial College London analyzed data from more than 112,000 volunteers who took Covid tests during the pandemic.
Analysis found that those admitted to intensive care with Covid scored on average around nine IQ points lower in exams than those who avoided infection.
Britons who avoided the disease tended to perform best in intelligence tests, while those who ended up in hospital performed the worst. (Stock image.)
Those who reported having Covid for a long time – persistent symptoms such as ‘brain fog’ – scored six points lower and those with only a mild infection 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 when comparing the groups, in an attempt to take other factors into account.
Further research found a long-lasting cognitive impact, even in people who had been infected a year or more previously.
The original Covid strain was associated with a greater drop in IQ, while with Omicron there were only marginal differences. Vaccination also appeared to have a protective effect.
Professor Hampshire said the implications of the figures are ‘quite scary’.
The participants had enrolled in Imperial College’s React study. Dr. Taquet said the results should be interpreted with caution because the study did not compare the same person before and after infection.
Those who reported having Covid for a long time – persistent symptoms such as ‘brain fog’ – scored six points lower and those with only a mild infection two points lower. (Stock image.)
Professor Benedict Michael, director of the University of Liverpool’s Neuroscience Laboratory for Infections, said there is “clearly a very seriously affected group”.
But he added: ‘I have yet to see compelling evidence that the vast majority of the population has been set back by X number of IQ points.’
Separate studies analyzing brain scans taken before and after the pandemic suggest that a Covid infection could have an impact even in those who are not hospitalized.
Professor Michael said it did not appear to be the virus infecting the brain, but a secondary result of an infection elsewhere in the body – possibly acting on blood vessels, reducing oxygen flow. Researchers say it remains unclear whether Covid patients’ brains will fully recover.