Severe COVID-19 patients experience cognitive decline years later

There is evidence that people who were hospitalized with COVID-19 during the first wave of the pandemic still have lower than expected cognitive abilities several years later, forcing them to change jobs.

“What we found is that the average cognitive impairment is equivalent to 10 IQ points, based on what you would expect given age etc.,” says Maxime Taquet of the University of Oxford.

His team looked at 475 British people who had been admitted to and discharged from hospital with COVID-19 up to March 31, 2021.. All of the participants had undergone psychiatric and cognitive evaluations six months after they were discharged, as part of a separate study. Take’s team asked them to be reassessed two to three years later and found that, on average, symptoms of depression, anxiety, and fatigue had worsened. “More people get worse than they get better,” Take says.

Overall, those suffering from moderate to severe depression increased from 34% at six months to 47% at the second assessment, and those suffering from moderate to severe fatigue increased from 26% at the first test to 40%. Smaller changes were seen in the proportion of those suffering from moderate to severe anxiety, increasing from 23% to 27%.

It’s not clear why so many people’s symptoms worsened, but the team found that people whose symptoms were more severe in the initial tests tended to get worse over time. One participant said he’d had shortness of breath for three years and it was hard for him not to fall into depression, Take said.

The team also found that more than a quarter of participants changed jobs after hospitalization, half of whom said they did so because of poor health. The researchers found a strong association between changing jobs and declining cognitive function, but not with depression, anxiety, or fatigue. This suggests that many people are changing jobs because they can no longer cope with the cognitive demands of their previous jobs, rather than for a lack of energy or interest, Take says.

He acknowledges that the study has major limitations: Only a fifth of those invited to take part actually did so, so it’s unclear how representative the study is. And because the participants weren’t tested before being admitted, there’s no baseline to compare it to, says Paul Harrison, another Oxford researcher. Instead, the conclusion that there was an average 10-point drop in IQ relies on what would be expected for people of the same age, sex and education level, based on a survey called the Great British Intelligence Test.