people who have had Covid-19 have a higher risk of neurological and psychiatric diseasesincluding mental confusion, dementia and psychosis, two years later, compared with those who have had other respiratory infections, according to the largest study of its kind published by The Lancet Psychiatry.
Patients also face an increased risk of anxiety and depression, the research suggests, but this disappears within two months of having Covid-19. Two years later, the risk is no more likely than after other respiratory infections.
Previous studies have found that people face increased risks of various neurological and mental health conditions in the first six months after infection. However, until now there has been no large-scale data examining the risks over a longer period of time. The new study, conducted by the University of Oxford and the National Institute for Health and Care Research at the Oxford Center for Biomedical Health Research, looked at 1.28 million cases of Covid-19 over two years.
In this analysis of 2-year retrospective cohort studies, the researchers drew data from the TriNetX electronic medical record network, an international network of de-identified data from health care records of approximately 89 million patients collected from hospital, health care providers primary and specialists. (mainly from the US, but also from Australia, UK, Spain, Bulgaria, India, Malaysia, and Taiwan).
A cohort of patients of any age with Covid-19 diagnosed between January 20, 2020 and April 13, 2022 and propensity score (1:1) was compared with a contemporary cohort of patients with any other respiratory infection. Matching was done by age group based on demographic factors, risk factors for COVID-19 and severe COVID-19 disease, and vaccination status. They also estimated how many people died after a neurological or psychiatric diagnosis during follow-up in each age group.
They identified 1,487,712 patients with a registered diagnosis of Covid-19 during the study period, of whom 1,284,437 were adequately matched with the same number of patients with another respiratory infection. The risk trajectories of outcomes after SARS-CoV-2 infection across the entire cohort differed substantially.
The risks of common psychiatric disorders (mood and anxiety) returned to baseline after 1 to 2 months and subsequently reached an overall incidence equal to that of the matched comparison group. In contrast, the risks of cognitive deficits (known as brain fog), dementia, psychotic disorders, and epilepsy or seizures were still increasing at the end of the 2-year follow-up period.
Los adults age 64 or younger who passed the Covid-19 had a increased risk of brain fog than those with other respiratory infections. In those older than 65 years, there was a higher incidence of brain fog, dementia, and psychotic disorders compared to those who previously had a different respiratory infection.
The results in children showed similarities and differences with adults. The probability of most diagnoses after Covid-19 was lower than in adults, and they were not at higher risk of anxiety or depression than children who had other respiratory infections. Like adults, however, children recovering from Covid-19 were more likely to be diagnosed with some conditions, including seizures and psychotic disorders.
The fact that the neurological and psychiatric outcomes were similar during Delta and Omicron waves indicates that the burden on the health system could continue even with variants that are less severe in other respects.
The researchers acknowledge that there are some important limitations to consider. The study may underrepresent self-diagnosed and asymptomatic cases of Covid-19, as they are unlikely to be recorded. It also did not look at the severity or duration of conditions after Covid-19 and how they compare to other respiratory infections.
“It is good news that over-diagnosis of depression and anxiety after Covid-19 is short-lived and not seen in children. However, it is worrying that some other disorders, such as dementia and seizures, remain more likely to be diagnosed after Covid-19, even two years later,” says Professor Paul Harrison, who led the study at the University of Oxford.