Cognitive and Mental Health Decline Persists Years After COVID-19 Hospitalization

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Long COVID has become a major public health concern, referring to a diverse group of symptoms that can persist in people who have recovered from infection with SARS-CoV-2.

A new study following individuals hospitalized during the first wave of the pandemic has highlighted the persistent, significant nature of these symptoms and the emergence of new symptoms years after COVID-19 was first present.

Published in the journal Lancet Psychiatry, the findings suggest that many people who were hospitalized with COVID-19 continue to have cognitive and psychiatric problems two to three years post-infection.

Severe COVID-19 sufferers continue to show cognitive decline

Most studies investigating neuropsychiatric outcomes of COVID-19 beyond 18 months post-infection have relied on electronic health records. Such studies are hindered as they cannot distinguish emergent disorders from delayed diagnosis, nor can they ascertain the duration and severity of symptoms.

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The current study of 475 participants comprised individuals who were hospitalized during the first wave of the pandemic and consented to follow-up assessments (as part of the PHOSP-COVID study). This is one of the first prospective cohort studies to assess trajectories of psychiatric and cognitive symptoms over the first two to three years post-hospitalization for COVID-19.

Participants were invited to complete a set of online cognitive tests and to report their symptoms of depression, anxiety, fatigue and their subjective perception of memory problems. They were also asked whether they had changed their occupation and why.

The researchers found that participants scored significantly lower in cognitive tests two to three years after being infected with COVID-19. The average deficit was equivalent to 10 IQ points.

A substantial proportion of individuals reported severe symptoms of depression (22.4%), fatigue (24.6%), and subjective memory problems (24.9%), with these symptoms worsening over time.

At two to three years, these symptoms were already present six months post-infection in many participants. However, some participants also described experiencing new symptoms within the same period after their infection. New symptoms often emerged in individuals who had already exhibited other symptoms at six months post-infection.

“Long-term consequences, especially for thinking skills, have been noted in several reports and of course by the COVID-19 survivors themselves,” said Professor Dame Til Wykes, head of the School of Mental Health at King’s College London. “This paper quantifies their concerns and points out that we need better interventions to prevent or treat these long-term issues.”

More than one in four (26.9%) participants reported changing their occupation with many giving poor health as a reason. This change in occupation was associated with cognitive deficits and not with depression or anxiety.

“The robust and specific association between occupation change and cognitive deficits (both objective and subjective) suggests that many people who changed occupation in the months and years after acute COVID-19, did so because they could no longer meet the cognitive demands of their job rather than because they lacked energy, interest or confidence,” the researchers said.

New symptoms mostly affected people already experiencing symptoms at six months. The researchers suggest therefore that early treatment of the initial symptoms might be an effective way to prevent longer-term psychiatric and cognitive problems.

“Survivors of COVID-19 clearly deserve further clinical interventions focussing on their key long-term problems, this paper shows that they were not imagining them,” said Wykes.

Public relevance of these findings

While these findings offer new insights into how psychiatric and cognitive symptoms appear to change over the first two to three years post-hospitalization, the findings may not be generalizable.

“These results are important, but they refer to those who were the most affected by COVID-19,” said Wykes. “New treatments that have been introduced, as well as vaccinations, will reduce the numbers of people needing admission and should decrease these after-effects.”

The study sample consisted of individuals hospitalized during the first wave of the pandemic before vaccines were available. Of the individuals invited to the study only 20% consented to follow-up assessments.

“I think it’s very difficult to decide what this study tells us about the prevalence of problems after infection with COVID-19 because 2,469 volunteers were invited to participate in the study but only 475 actually did so, fewer than 1 in 5,” explained Professor David Curtis, honorary professor at University College London. “It is easy to speculate that those who agreed were those who were more likely to have experienced deterioration of their mental health, cognitive function and/or occupational function, whereas people who were now functioning well post-COVID might have been less motivated.”

The researchers also caution that while this study provides insights into the long-term effects of COVID-19, further research is essential to develop effective interventions. The researchers conclude that the next steps in this research will involve understanding the biological mechanisms driving these symptoms and identifying therapeutic strategies to promote cognitive recovery or prevent further decline.

Reference: Taquet M, Skorniewska Z, Deyn TD, et al. Cognitive and psychiatric symptom trajectories 2–3 years after hospital admission for COVID-19: a longitudinal, prospective cohort study in the UK. Lancet Psychiatry. 2024. doi: 10.1016/S2215-0366(24)00214-1

This article is a rework of a press release. Material has been edited for length and content.