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Cognitive decline accelerated in over 50s during pandemic, study finds

BMJ 2023; 383 doi: https://doi.org/10.1136/bmj.p2596 (Published 06 November 2023) Cite this as: BMJ 2023;383:p2596
  1. Owen Dyer
  1. Montreal

The covid-19 pandemic brought a “sustained decline in cognition” to people in the UK aged over 50, including those who did not fall sick, showed a large longitudinal study that tracked the same people before and after SARS-CoV-2 struck.

The research, published in the Lancet Healthy Longevity,1 found that the normal process of cognitive decline accelerated sharply in the first year of the pandemic. In the second year the rate of decline slowed but remained worse than the rate before the pandemic.

In the two years from March 2020 the 3142 participants in the study, who had a mean age of 67, saw their scores in executive function tests fall at an annual rate 49% faster than in the year before the pandemic. Their working memory scores fell 55% faster.

The decline was statistically robust for both executive function and working memory in the overall cohort of 3142 participants, in the 752 who reported covid infection during the two years, and in the 147 who already had a diagnosis of mild cognitive impairment (MCI) at the outset of the pandemic. People who were infected experienced a slightly faster decline than those who were not, and those with existing MCI saw the fastest decline in cognitive scores.

When researchers asked the trial participants about their exposure to known risk factors for cognitive decline, increased alcohol use and reduced exercise were found to have the strongest associations with lower scores in the pandemic’s first year across the whole cohort. Among the subgroups of participants who had contracted covid or had previous MCI, depression was found to be significantly associated with accelerated loss of working memory. Among people with MCI self-reported loneliness was also significantly associated with rapid memory decline.

Previous research has shown that people around the world exercised less and drank more alcohol in the pandemic’s first year.[2] [3]

In the pandemic’s second year, reduced exercise was the only factor still negatively affecting executive function scores across the whole cohort. But among those with pre-existing MCI loneliness and depression were still significant drivers of worsening memory. Loneliness and depression also continued to affect the scores of people who had caught the virus, among whom reduced exercise in the second year was also strongly associated with declining memory.

The study was led by researchers at King’s College London and the University of Exeter and was partly funded by the UK’s National Institute for Health and Care Research. The study population, comprising people who had signed up for the long running Protect study, is more educated than the UK national average.

“Our findings suggest that lockdowns and other restrictions we experienced during the pandemic have had a real lasting impact on brain health in people aged 50 or over, even after the lockdowns ended,” said Anne Corbett, a professor in dementia research who leads the Protect study at Exeter. “This raises the important question of whether people are at a potentially higher risk of cognitive decline, which can lead to dementia,” she added. “Our findings also highlight the need for policymakers to consider the wider health impacts of restrictions like lockdowns when planning for a future pandemic response.”

Coauthor Dag Aarslund, of King’s College London, said, “The current study underlines the importance of careful monitoring of people at risk during major events such as the pandemic. On a positive note, there is evidence that lifestyle changes and improved health management can positively influence mental functioning.”

About 10% of people with mild cognitive impairment currently receive a diagnosis of dementia each year, the authors wrote. “The data indicate that the pandemic conditions have accelerated cognitive decline in these individuals, and a key emerging question is whether their risk of conversion to dementia has also increased.”

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