The occurrence of mental health conditions and neurological disorders among people recovering from Covid-19 has been a concern since the start of the pandemic. Several studies have shown that a significant proportion of adults face the problems of this type, and that the risks are greater than after other infections.
However, several questions remain. Do the risks of psychiatric and neurological problems dissipate and, if so, when? Are the risks similar in children and adults? Are there differences between the Covid variants?
Our new study, published in The Lancet Psychiatry, explored these issues. In the analyzes led by my colleague Maxime Taquet, we used the electronic health records of around 1.25 million people diagnosed with Covid, mostly from the US. We tracked the occurrence of 14 neurological and psychiatric diagnoses significant in these patients for up to two years.
We compared these risks with a closely matched control group of people who had been diagnosed with a respiratory infection other than Covid.
We examine children (under 18), adults (18-65), and older adults (over 65) separately.
We also compared people who contracted Covid just after the appearance of a new variant (notably omicron, but also older variants) with those who contracted it just before.
Our findings are a mix of good and bad news. Reassuringly, although we observed an increased risk of common psychiatric disorders (anxiety and depression) after Covid infection, this elevated risk declined rapidly. The rates of these disorders among people who had covid were no different from those with other respiratory infections over a couple of months, and there was no overall excess of these disorders over the two years.
It was also good news that children were not at increased risk for these disorders at any stage after covid infection.
We also found that people who had had covid were not at increased risk of Parkinson’s disease, which had been a concern early in the pandemic.
Other findings were more worrying. The risks of being diagnosed with some disorders, such as psychosis, seizures or epilepsy, mental confusion and dementia, while still mostly low, remained elevated for two years after covid infection. For example, the risk of dementia in older adults was 4.5% in the two years after Covid, compared to 3.3% in those with another respiratory infection.
We also saw a continued risk of psychosis and seizures in children.
In terms of variants, although our data confirm that omicron is a much milder disease than the previous delta variant, survivors were still at similar risk for the neurological and psychiatric conditions we analyzed.
However, given the recent emergence of omicron, the data we have for people who were infected with this variant only goes back to about five months after infection. So the image can change.
COVID-19 Protect yourself
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— PCADG Davao Region (@davao_pcadg) August 14, 2022
Mixed results
Overall, our study reveals a mixed picture, with some disorders showing transient excess risk after Covid, while other disorders have sustained risk. For the most part, the results are reassuring in children, but with a few worrying exceptions.
The results for omicron, the currently dominant variant worldwide, indicate that the burden of these disorders is likely to continue, although this variant is milder in other respects.
The study has important caveats. Our findings don’t capture people who may have had COVID but it wasn’t documented in their health records, perhaps because they didn’t have symptoms.
And we can’t fully account for the effect of vaccination, because we didn’t have complete information on vaccination status, and some people in our study contracted Covid before vaccines were available. That said, in a previous study we show that the risks of these results were quite similar in people who contracted covid after being vaccinated, so this might not have significantly affected the results.
Furthermore, the risks observed in our study are relative to people who had had other respiratory infections. We don’t know how they compare to people without any infection. We also don’t know how severe or long-lasting the disorders were.
Finally, our study is observational and therefore cannot explain how or why Covid is associated with these risks. Current theories include persistence of the virus in the nervous system, immune reaction to infection, or problems with the blood vessels. These are being investigated in separate investigation.
This article first appeared on The conversation.
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