The study’s findings were a mix of good and bad news, said Paul Harrison, a professor of psychiatry at Oxford University and the study’s lead author. Among the reassuring aspects was the rapid resolution of symptoms such as depression and anxiety.
“I was surprised and relieved at how quickly the psychiatric sequelae subsided,” Harrison said.
David Putrino, director of rehabilitation innovation at Mount Sinai Health System in New York, who has been studying the lasting impacts of the coronavirus since the beginning of the pandemic, said the study revealed some very troubling results.
“It allows us to see without a doubt the emergence of significant neuropsychiatric sequelae in individuals who had covid and much more frequently 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 this is not strictly long-term research.
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“It would be exaggerated and unscientific to make the immediate assumption that everyone [study] The cohort had covid for a long time,” Putrino said. But the study, he said, “reports long-term investigations of covid.”
Between 7 million and 23 million people in the United States, according to recent government estimates, have long-term covid, a term that refers to a wide range of symptoms, including fatigue, shortness of breath and anxiety, that persist for weeks and months after the acute infection has subsided. These numbers are expected to rise as the coronavirus becomes an endemic disease.
The study was led by Maxime Taquet, a senior researcher at the University of Oxford who specializes in using big data to shed light on psychiatric disorders.
The researchers matched nearly 1.3 million patients with a diagnosis of covid-19 between January 20, 2020 and April 13, 2022, with an equal number of patients who had other respiratory illnesses during the pandemic. The data, provided by the TriNetX electronic health record network, came largely from the United States, but also included data from Australia, Great Britain, Spain, Bulgaria, India, Malaysia and Taiwan.
The study group, which included 185,000 children and 242,000 older adults, revealed that the risks varied by age, with those aged 65 and over at the highest risk of lasting neuropsychiatric effects.
For people aged 18-64, a particularly significant increase in risk was persistent brain fog, which affected 6.4% of people who had had covid compared to 5.5% of the group control
Six months after infection, the children were not found to be at increased risk of mood disorders, although they remained at increased risk of brain fog, insomnia, stroke and epilepsy. None of these effects were permanent for the children. With epilepsy, which is extremely rare, the increased risk was greater.
The study found that 4.5% of the elderly developed dementia within two years of infection, compared with 3.3% of the control group. This 1.2-point increase in a diagnosis as damaging as dementia is particularly concerning, the researchers said.
The study’s reliance on reams of de-identified electronic health data raised some caveats, especially given the tumultuous timing 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.
“I personally find it impossible to judge the validity of data or conclusions when the source of the data is shrouded in mystery and the sources of the data are kept secret by legal agreement,” said Harlan Krumholz, a Yale scientist who has developed an online study. platform where patients can enter their own health data.
Taquet said the researchers used several means to evaluate the data, including making sure it reflected what was already known about the pandemic, such as the drop in death rates during the omicron wave.
In addition, Taquet said, “the validity of the data will not be better than the validity of the diagnosis. If doctors make mistakes, we will make the same mistakes.”
The study follows earlier research by the same group, which reported last year that a third of covid patients experienced mood disorders, strokes or dementia six months after infection.
While cautioning that it is impossible to make full comparisons between the effects of recent variants, including omicrons and their subvariants, that currently cause infections, and those that were prevalent a year or more ago, the researchers outlined some initial findings: all and that omicrons caused less severe immediate symptoms, long-term neurological and psychiatric outcomes appeared similar to delta waves, indicating that the burden on the world’s healthcare systems could continue even with less severe variants.
Hannah Davis, co-founder of the Patient-Led Research Collaborative, which has been studying covid for a long time, said the finding was significant. “It goes against the narrative that omicron is milder for a long covid, which is not based on science,” Davis said.
“We see it all the time,” Putrino said. “The general conversation does not leave covid aside for a long time. The severity of the initial infection doesn’t matter when we’re talking about long-term sequelae that ruin people’s lives.”
Dan Keating contributed to this report.