Within six months of being diagnosed with Covid-19, more than 33% of patients were diagnosed with a neuropsychiatric condition—and severe neurological conditions, such as stroke and dementia, accounted for a low but significant proportion of those diagnoses, according to a new study in The Lancet Psychiatry.
For the study, Paul Harrison, a professor of psychiatry at the University of Oxford, and colleagues examined the EHRs of about 81 million patients. Of those, the researchers identified 236,379 patients—most of whom were American—who had been diagnosed with Covid-19 after January 20, 2020, and who were still alive as of December 13, 2020.
The researchers then compared the incidence rate of 14 psychiatric and neurological conditions among that cohort with three similar cohorts: one cohort of 105,579 patients who had been diagnosed with the flu; another cohort of 236,038 patients who had been diagnosed with a respiratory illness such as pneumonia or sinusitis; and a third cohort who were hospitalized for unrelated conditions, such as broken bones or gallstones.
The psychiatric and neurological outcomes the researchers assessed included ischemic stroke, Guillain-Barré syndrome, dementia, mood disorders, anxiety, insomnia, and substance misuse, among others.
Overall, the researchers found that 33.62% of patients who had received a Covid-19 diagnosis experienced at least one of the 14 assessed neurological or psychiatric conditions. About one in eight patients, or 12.84%, had never before received a neuropsychiatric diagnosis.
According to the researchers, anxiety (17%) and mood disorders (14%) were the most common neuropsychiatric diagnoses among the patients studied. However, the researchers also identified lower, but still significant, rates of severe neurological complications. Among all patients studied, 0.6% developed a brain hemorrhage, 2.1% experienced an ischemic stroke, and 0.67% were diagnosed with dementia.
The researchers also found that while people who were diagnosed with anxiety or depression had experienced a wide range of illness severity when sick with Covid-19, those who experienced stroke or dementia generally had severe cases of Covid-19. According to the researchers, patients who had been admitted to intensive care while sick with Covid-19 were not only more likely to be later diagnosed with any of the 14 assessed neuropsychiatric conditions (46.9%)—and more likely to have that diagnosis be a first-time event (25.79%)—they were also more likely to have a stroke (6.92%) or be diagnosed with dementia (1.74%).
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Overall, according to the researchers, patients who had received a Covid-19 diagnosis had a 44% higher risk of a neuropsychiatric diagnosis than those who had been diagnosed with the flu, and about a 16% higher risk than those who'd received any respiratory tract illness diagnosis. The researchers did find two exceptions to the trend, however, with no increased risk of either Parkinson's disease or Guillain-Barré syndrome.
According to Max Taquet, a clinical fellow in psychiatry at Oxford and co-author of the study, the findings demonstrate an "urgent" need to research "how and why…this occur[s] in patients with Covid-19 and how they can be treated and (how to) prevent it." However, he added that "regardless of the explanation, health services need to be prepared for the increased demand that this data is showing."
In an accompanying editorial, Jonathan Rogers and Anthony David, both of University College London, echoed those concerns, writing, "Sadly, many of the disorders identified in this study tend to be chronic or recurrent, so we can anticipate that the impact of Covid-19 could be with us for many years."
Separately, Simon Wessely, chair of psychiatry at King's College London, called the study "very important," adding, "It confirms beyond any reasonable doubt that Covid-19 affects both brain and mind in equal measure."
However, the study authors also cited several study limitations.
Masud Husain, a professor of neurology and cognitive neuroscience at Oxford and study co-author, explained while the EHRs indicated whether someone had previously experienced a stroke or received a neuropsychiatric diagnosis, they couldn't specify whether someone was going to have a recurrence regardless of Covid-19—such an assessment would require longer-term research. Further, he noted that the study didn't account for people who contracted Covid-19 but who either did not test positive or did not seek out medical care.
Conversely, Taquet noted that people with Covid-19 might simply be more likely to be diagnosed with a neuropsychiatric disorder because they were receiving more medical attention than those in the cohort groups.
And Allison Navis—an assistant professor in the neuro-infectious diseases division at the Ichan School of Medicine at Mount Sinai and lead clinical neurologist at Mount Sinai's post-Covid clinic, who was not involved in the study—cautioned that the findings shouldn't be sensationalized. She explained that while "the 12.8% who have a new diagnosis of something neuropsychiatric can sound very sensational," it's important to recognize that "the more severe things like strokes are still fairly uncommon. I don't want people thinking that 1 in 10 people get a stroke with Covid" (Cooney, STAT News, 4/6; Owens, "Vitals," Axios, 4/7; Kelland, Reuters, 3/7; George, MedPage Today, 4/6).