Health problems and brain fog can linger for years in people hospitalized for Covid early in the pandemic, with some patients developing more severe or new symptoms after 12 months, researchers say.
They found that many people with long Covid improved over time, but a significant proportion still had cognitive problems two to three years later, and symptoms of depression, anxiety and fatigue worsened rather than improved.
The scientists studied long Covid in 475 people who were hospitalized with the virus before vaccines were available. They wanted to know whether brain fog, fatigue and mental health problems persisted or only developed after the first year.
Although researchers had no information about the participants’ thinking skills before they got Covid, cognitive tests two to three years later showed that patients’ IQs were, on average, 10 points lower than expected for their age, education and other factors. One in nine showed signs of “severe cognitive deficits,” equivalent to an IQ 30 points lower than expected.
Questionnaires completed by participants showed that many felt moderate to severe levels of depression (47%), fatigue (40%) and anxiety (27%) two to three years after Covid. Rather than improving over time, symptoms were on average worse two to three years after infection than six to 12 months.
“What we knew before we did the study was that COVID-19 was associated with a greater risk of cognitive problems, depression and anxiety compared to other respiratory infections,” said Dr. Max Taquet, an author of the study from the University of Oxford. “We found that there was a substantial neuropsychiatric burden in our cohort after two to three years.”
More than one in four people in the study changed jobs after contracting the virus, often because they could no longer meet the cognitive demands of their job.
People who got worse over the years tended to be among the sickest six months after infection. However, the severity of the original illness did not seem to affect their long-term outcome.
Although the percentage of patients reporting depression, anxiety and fatigue increased after six months, cognitive problems appeared to improve. Six months after infection, 44% had objective cognitive deficits compared to 33% after two to three years.
The work, published in Lancet Psychiatryled the authors to stress the importance of diagnosing and treating long-term Covid symptoms early to reduce the risk of people developing a more complex condition.
The number of people with long Covid continues to grow, with 2 million people in England and Scotland now experiencing symptoms, according to the Office for National Statistics. The brain fog many are reporting is equivalent to a six-point drop in IQ, a recent study found.
Danny Altmann, professor of immunology at Imperial College London, who was not involved in the research, said the findings were “profound and alarming” and warned people not to be complacent in the era of vaccines and milder Covid variants.
The risk of long Covid has fallen from around 10% in the first wave of infections to around 2.5% today, but that still represents a “huge number of cases,” Altmann said. “There could be no clearer warning that Covid-19 is here and can still do terrible things to you, so it’s worth staying pepped up and avoiding reinfection.”
However, the scientists urge caution about the results. Only 19% of the 2,500 people invited to the study took part, and if those who agreed did much worse or much better than the broader group, that would skew the results. It is also unclear whether people who developed long Covid later in the pandemic, after vaccination and without hospitalization, would experience serious health problems.