New Study Suggests Covid Increases Risk of Brain Disorders

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A study published this week in the journal Lancet Psychiatry showed an increased risk of some brain disorders two years after infection with the coronavirus, shedding new light on the long-term neurological and psychiatric aspects of the virus.

The analysis, conducted by researchers at the University of Oxford and based on health data from more than 1 million people worldwide, found that while the risks of many common psychiatric disorders returned to normal within a few months, people were at increased risk for dementia, epilepsy, psychosis and cognitive impairment (or brain fog) two years after contracting covid. Adults appeared to be at particular risk for persistent brain fog, a common complaint among coronavirus survivors.

The study’s findings were a mix of good and bad news, said Paul Harrison, a professor of psychiatry at the University of Oxford and the study’s senior author. One of the reassuring aspects was the rapid resolution of symptoms such as depression and anxiety.

“I was surprised and relieved by how quickly the psychiatric effects dissipated,” Harrison said.

David Putrino, director of rehabilitation innovation at Mount Sinai Health System in New York, which has been studying the lasting effects of the coronavirus since the start of the pandemic, said the study revealed some very troubling results.

“It allows us to see without a doubt the emergence of significant neuropsychiatric consequences in individuals who had covid and much more often than those who did not,” he said.

Because it focused only on the neurological and psychiatric effects of the coronavirus, the study authors and others emphasized that it is not strictly a long-term covid study.

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“It would be an exaggeration and unscientific to immediately assume that everyone in the… [study] cohort had covid for a long time,” Putrino said. But the study, he said, “does inform about long covid research.”

According to recent government estimates, between 7 million and 23 million people in the United States have long had covid — an umbrella term for a wide variety of symptoms, including fatigue, shortness of breath and anxiety that last for weeks and months after the acute infection clears. Those numbers are expected to rise as the coronavirus establishes itself as an endemic disease.

The study was led by Maxime Taquet, a senior research fellow at the University of Oxford who specializes in using big data to shed light on psychiatric disorders.

Between January 20, 2020 and April 13, 2022, the researchers matched nearly 1.3 million patients diagnosed with Covid-19 with an equal number of patients with other respiratory illnesses during the pandemic. The data, provided by the electronic health record network TriNetX, came largely from the United States, but also includes data from Australia, Great Britain, Spain, Bulgaria, India, Malaysia and Taiwan.

The study group, which consisted of 185,000 children and 242,000 older adults, revealed that the risks varied by age, with those over 65 at the highest risk of lasting neuropsychiatric effects.

For people aged 18 to 64, there was a particularly significant increased risk of persistent brain fog, affecting 6.4 percent of people who had had Covid, compared with 5.5 percent in the control group.

Six months after infection, children were not found to be at increased risk for mood disorders, although they did have a higher risk of brain fog, insomnia, stroke and epilepsy. None of those effects were permanent for children. In epilepsy, which is extremely rare, the increased risk was greater.

The study found that 4.5 percent of the elderly developed dementia in the two years after infection, compared with 3.3 percent of the control group. That 1.2 point increase in a diagnosis as damaging as dementia is particularly concerning, the researchers said.

The study’s reliance on a large body of unidentified electronic health data sparked some caveats, especially given the tumultuous time of the pandemic. Tracking long-term outcomes can be difficult when patients may have sought care through many different health systems, including some outside the TriNetX network.

“Personally, I find it impossible to judge the validity of the data or the conclusions when the data source is shrouded in mystery and the sources of the data are kept secret by legal agreement,” said Harlan Krumholz, a Yale scientist who conducts an online survey. platform where patients can enter their own health data.

Taquet said the researchers used several ways to assess the data, including making sure they reflected what was already known about the pandemic, such as the drop in death rates during the ommicron wave.

Taquet also said, “Data validity will not be better than diagnosis validity. If clinicians make mistakes, we will make the same mistakes.”

The study follows on from previous research by the same group, which reported last year that a third of Covid patients experienced mood disorders, stroke or dementia six months after infection.

While they caution that it is impossible to make full comparisons between the effects of recent variants, including omicron and its subvariants, which currently cause infections, and those that were common a year or more ago, the researchers outlined some preliminary findings: Although omicron caused less severe immediate symptoms, the longer-term neurological and psychiatric outcomes appeared comparable to the delta waves, indicating that the burden on global health care systems could continue even with less severe variants.

Hannah Davis, co-founder of the Patient-Led Research Collaborative, which has long studied covid, said the finding made sense. “It goes against the story that omicron is milder for long-term covid, which is not based on science,” Davis said.

“We see this all the time,” Putrino said. “The general conversation will not be taken into account for a long time because of covid. The severity of the initial infection doesn’t matter when we talk about long-term consequences that ruin people’s lives.”

Dan Keating contributed to this report.

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