Here’s how COVID affects mental health and brain disorders

However, many questions remain. Are the risks of psychiatric and neurological problems eliminated, and if so, when? Are the risks in children the same as in adults? Is there a difference between the COVID variants?

Our new study, published in The Lancet Psychiatry, explores these issues. In the analyses, led by my colleague Maxime Taquet, we used the electronic health records of nearly 1.25 million people diagnosed with COVID, most of them from the US. We tracked the occurrence of 14 major neurological and psychiatric diagnoses in these patients for two years.

We compared these risks to a closely matched control group of people who were diagnosed with respiratory infections other than COVID.

We examined children (under 18 years of age), adults (18–65) and older adults (over 65 years of age) separately.

We also compared people who contracted COVID after the emergence of a new variant (notably Omicron, but also earlier variants) to those who had previously done so.

Our findings are a mix of good and bad news. Reassuringly, although we observed a greater risk of common psychiatric disorders (anxiety and depression) following COVID infection, this increased risk rapidly decreased. In people who had COVID, the rate of these disorders was no different from those who had other respiratory infections within a few months, and there was no exacerbation of these disorders at two years.

It was also good news that children were not at higher risk of these disorders at any stage after COVID infection.

We also found that people who had had COVID did not have a higher risk of getting Parkinson’s disease, which was a concern at the start of the pandemic.

Other findings were more worrying. The risks of being diagnosed with certain disorders, such as psychosis, seizures or epilepsy, brain fog and dementia, although mostly still low, remained high throughout the two years following COVID infection. For example, the risk of dementia in older adults was 4.5% in the two years following COVID, compared to 3.3% in those with other respiratory infections.

We also looked at increased risk of psychosis and seizures in children.

In terms of variants, although our data confirm that Omicron is a much milder disease than previous delta variants, survivors remained at similar risk of neurological and psychiatric conditions that we observed.

However, given how recently the omicron emerged, the data we have for people infected with this type only goes back to about five months after infection. So the picture may change.

mixed results

Overall, our study paints a mixed picture, with some disorders showing a transient additional risk after COVID, whereas other disorders have a sustained risk. For the most part, the findings are reassuring in children, but with a few exceptions.

The results on Omicron, which is currently prevalent worldwide, indicate that the burden of these disorders is likely to continue, even if this variant is mild in other respects.

The study has important caveats. Our findings do not capture people who may have had COVID, but it was not recorded in their health records – probably because they did not have symptoms.

And we cannot fully account for the impact of vaccination, because we did not have complete information about vaccination status, and some people in our study caught COVID before vaccines were available. That said, in a previous study we showed that the risks of these outcomes were quite similar among people who caught COVID after vaccination, so this may not have had a significant impact on the outcomes.

Furthermore, the risks observed in our study are relative to those who had other respiratory infections. We don’t know how they compare to people without any infections. We also don’t know how severe or long-lasting the disorders were.

In conclusion, our study is based on observation and therefore cannot explain how or why COVID is associated with these risks. Current theories include persistence of the virus in the nervous system, the immune response to infection, or problems with blood vessels. They are being investigated in different research.

*by Paul Harrison, University of Oxford

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