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Six months after being diagnosed with Covid-19, 1 in 3 patients also had experienced a psychiatric or neurological illness, mostly mood disorders but also strokes or dementia, a large new study shows.

About 1 in 8 of the patients (12.8%) were diagnosed for the first time with such an illness, most commonly anxiety or depression. Compared to control groups of people who had the flu or other non-Covid respiratory infections, first-ever neuropsychiatric diagnoses were almost twice as high.

The study, published Tuesday in The Lancet Psychiatry, used real-world health data on millions of people to gauge the incidence of 13 brain disorders. Anxiety, mood, and substance use disorders were most common, but the researchers also found worrying, if lower, rates of serious neurological complications, especially in patients who had been severely ill with Covid-19. In all Covid-19 patients, 0.6% developed a  brain hemorrhage, 2.1% an ischemic stroke, and 0.7% dementia. 

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“We need urgent research to better understand how and why does this occur in patients with Covid-19 and how they can be treated and [how to] prevent it,” Max Taquet, a clinical fellow in psychiatry at the University of Oxford and a study co-author, said on a call with reporters on Tuesday. “But we think that regardless of the explanation, health services need to be prepared for the increased demand that this data is showing.” 

The size of the study lends confidence to its findings, which confirm what has been hinted in smaller studies, including earlier work from the Oxford group. The researchers analyzed electronic health records of 81 million U.S. patients (both insured and uninsured), finding 236,379 people who had been diagnosed with Covid-19 and comparing them to three cohorts of similar people: one cohort had the flu, another had another respiratory illness such as sinusitis or pneumonia, and one cohort included people who were hospitalized for unrelated conditions such as bone fractures or gallstones. The researchers hoped that comparing the Covid group to the others would help isolate Covid-19 as a cause and tease out its effects on the brain. 

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After accounting for patients’ age, sex, ethnicity, and existing health conditions, patients overall had a 44% higher risk of neurological and mental health diagnoses after Covid-19 than after flu, and a 16% higher risk after Covid-19 than after other respiratory tract infections. 

There were two exceptions: The researchers did not see increased risk of Parkinson’s disease, a movement disorder, or Guillain-Barré syndrome, which is a rare disorder that shows up after some viral infections as tingling and weakness when the immune system attacks nerves.

Allison Navis, assistant professor in the division of neuro-infectious diseases at the Icahn School of Medicine at Mount Sinai, sounded a note of caution. The lead clinical neurologist at Mount Sinai’s post-Covid clinic, she was not involved in the Lancet study.  

“It does highlight that there is something unique going on with Covid,” she told STAT. “And the 12.8% who have a new diagnosis of something neuropsychiatric can sound very sensational. That 12.8% encompasses depression and anxiety, so it’s extremely important to not minimize that and not make that sound like a lesser diagnosis at all, but 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.”

The new study reinforces previous research that showed some brain disorders increased with the severity of illness, going up in people who needed to be hospitalized and rising further in people who needed intensive care. While 33.6% of people developed a neuropsychiatric illness overall, that risk grew to 46.4% among Covid patients treated in an ICU.

What’s new is the distinction between neurological and psychiatric complications. People with very severe Covid-19 had a higher risk of complications like stroke or dementia, but people who developed anxiety or depression spanned the spectrum of illness severity. 

While the study did not examine the mechanisms that might explain neuropsychiatric disorders associated with the virus, the authors did speculate in the call with reporters that if patients know that they have Covid-19, that and other stressors might contribute to a psychiatric illness. “It could be psychological factors and biological factors and psychosocial factors, such as, for instance, the need to isolate and the loss of income as a result of that,” Taquet said. 

It’s easier to tie neurological disorders to the virus’ effects on the brain. Scientists believe the virus can enter the brain through the olfactory bulb, where taste and smell are decoded. Inflammation throughout the body also harms blood vessels in the brain, and can lead to stroke-causing blood clots, delirium, or dementia.

While the medical records could tell the researchers whether someone had previously suffered a stroke or been diagnosed with dementia, they couldn’t surmise whether someone was going to have a recurrence anyway or whether Covid-19 caused it, Masud Husain, professor of neurology and cognitive neuroscience at Oxford and a study co-author, warned. Longer follow-up will be needed to answer that question, but the signal was too strong to ignore, he said. 

Husain also cautioned that the numbers they reported could be an underestimate if they don’t include people who were infected with Covid but did not test positive for it, or if people had no symptoms that drove them to seek medical care. On the flip side, patients with Covid-19 might be more likely to have a neurological and psychiatric disorder diagnosed simply because they were receiving more medical attention compared to patients with the flu or other respiratory infections, Taquet pointed out.

This was not a study of long-Covid, said Paul Harrison, professor of psychiatry at the University of Oxford and a study co-author, referring to the constellation of lingering symptoms that overlap with some problems caused by the neuropsychiatric illnesses described in the current paper. But the need for more research and continued clinical care is the same.

“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,” Jonathan Rogers and Anthony David of University College London wrote in a commentary appearing with the Lancet study. 

  • I’m hoping they got approval from the 81 million people whose EHR’s they went through. That’s my only concern. This is a powerful study. I’ve been looking for some statistics.

  • My grandmother had Covid early on and months later out of the blue is suffering from severe dementia and neurological issues

  • As a behavioralist I am not surprised by this information on neuro psychiatric conditions increased by covid 19 but do find the parellel from people and similar symptoms of mad cow disease .

  • My aunt received the 2nd vaccine shot of Phizer vaccine. The following Monday she has brain fog. Is this temporary? this is the 3rd week. She can’t tell us what items are like a TV or bed or table. Everything is a thing!

  • I am interested in the working population who were diagnosed with Positive COVID-19 and have returned to work. Might you be able to refer me to a group interested &/or researching on the mental health and physical stamina of working adults post positive COVID-19 illness? Thank you, Pearl Garcia, DNP, FNP

  • My husband was recently in the hospital for 27 days due to a medical situation that had nothing to do with COVID. He became very mentally impaired solely due to “hospital dementia.” He had been “tortured” for weeks from confinement, daily blood tests, CT Scans, X’rays, IVs, needles, needles, and more needles. Once he was released, and returned home, his mental faculties has improved greatly. Whether he will ever return to being 100% the way he was before entering the hospital with double pneumonia, kidney failure, lung failure, and heart failure, is yet to be determined. It is my opinion that; once again, COVID is erroneously being blamed for something it was not responsible for.

    • Agreed. I wonder how the numbers compare to the general population over this past year. I have seen headlines stating that mental illness has risen dramatically for everyone due to the effects of quarantine and disruption of “normal life.”

  • The authors excluded from the control groups persons who subsequently developed COVID-19. This is ordinarily incorrect in follow-up studies, as it restricts the control group post hoc to persons less at risk for Covid-19 and possibly by correlation less at risk for other adverse outcomes as well. There are standard techniques for dealing with this phenomenon. The result may or may not be meaningfully affected by the bias, but for now, I’d hold off on any sweeping conclusion.

  • Gee, I think it has more to o with lock downs, loss of income, loss of social interactions, and fear spread by the media that it does the virus…

    • Absolutely – I wonder if the control group data was even sourced during the same time period I didn’t see that specifically mentioned. Sadly all media, government and most of academia has lost my trust.

    • I agree, 1 in 3 is a very huge number, but perhaps being confined didn’t help it either, when under stress, the symptoms of mental health are greatly exaggerated.

    • Eric K, absolutely right.

      Is epidemiology a truly scientifically serious field? I have always had my doubts, and studies like this, with many confounding factors, only increase these doubts. I wouldn’t presume to dispute the claims of some of the commenters here about their specific situations, and I wish them the best for a return to normalcy.

      However, studies like these, no doubt performed under at least SOME pressure to publish, don’t do anything but to get the public relations wheel in motion and have journalists breathlessly present the EXTREMELY tentative conclusions of such studies to a lay audience. Frankly, it serves only to increase the fear factor.

      Personally, I know people who have Covid and for them it was a very bad case of the flu? Are they outliers? Or are they emblematic? Right now, our epidemiological betters are still guessing about that and many many other things related to this virus.

      The late great Lewis Thomas wrote decades ago that “health” is by and large the normal state of affairs for most people–and this before some of the miraculous therapies we have today. What he said back then is true now.

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