Cognitive function and working memory declined in people aged 50 and older during the pandemic, even if they were not infected with the virus, British researchers have said.
The pandemic, they found, caused sustained harm to the brain health of older adults, and affected their cognitive function – regardless of whether or not they caught the virus – more quickly during the first year of the pandemic, between March 2020 and February 2021.
The trend continued into 2021/22, suggesting an impact beyond the initial lockdowns, reports The Guardian.
Almost 780m people were killed or made ill by the coronavirus, according to the World Health Organisation, health experts are still learning about the indirect effects of the biggest public health crisis in a century.
The research is the largest of its kind to link the pandemic conditions – and the enormous lifestyle shifts triggered by lockdowns and other Covid restrictions – to sustained cognitive decline.
This acceleration has been exacerbated by various factors since the arrival of Covid, the researchers said. These included an increase in loneliness and depression, a drop in exercise, higher alcohol consumption, as well as the effects of the disease itself.
The study, led by the University of Exeter and King’s College London, was published in The Lancet Healthy Longevity journal.
Anne Corbett, a professor in dementia research and the lead at Exeter for the Protect study, said: “Our findings suggest that lockdowns and other restrictions during the pandemic have had a real lasting impact on brain health in people aged 50 or over, even after the lockdowns ended.
“This raises the important question of whether people are at a potentially higher risk of cognitive decline, which can lead to dementia.
“It is now more important than ever to make sure we are supporting people with early cognitive decline, especially because there are things they can do to reduce their risk of dementia later on.
“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,” she added.
The researchers analysed brain function tests from 3 142 people who took part in the Protect study, which launched in 2014 to gain an insight into the brain function of people over 40 during a 25-year period.
The people assessed were all aged between 50 and 90 and based in the UK. Tests analysed participants’ short-term memory and their ability to complete complex tasks.
The study then looked at all the data collected over the year from March 2019 to February 2020, and compared it with the results from the pandemic’s first year (March 2020 to February 2021) and second year (March 2021 to February 2022).
Analysis showed the rate of cognitive decline quickened in the first year of the pandemic, and was higher among those who had already shown signs of mild cognitive decline before the outbreak of Covid-19.
“We found that people 50 and older in the UK had accelerated decline in executive function and working memory during the first year of the Covid-19 pandemic, during which the UK was subjected to three societal lockdowns for a total period of six months,” they wrote.
“Notably, however, this worsening in working memory persisted in the second year of the pandemic, after the social restrictions had eased. The scale of change is also of note, with all groups – the whole cohort and the individual subgroups – showing more than a 50% greater decline in working memory and executive function.”
They cautioned that the study was observational so could not prove cause and effect but said the rise in depression, loneliness and alcohol use and fall in exercise during Covid was “well known”.
“As such, there is a clear need to address these changes in lifestyle behaviour as a public health priority, and on the basis of the patterns of associations seen in the current study, we would hypothesise that interventions targeting these behaviours could benefit cognition.”
Dr Dorina Cadar, a senior lecturer in cognitive epidemiology and dementia at Brighton and Sussex Medical School, who was not involved with the study, said it was clear the effects of the pandemic on the general population had been “catastrophic”.
“The new findings from the Protect study indicate domain-specific cognitive changes for individuals with a history of Covid-19 that mirrored similar trajectories for those with mild cognitive impairment but with a slightly lower rate of decline,” said Cadar in a linked comment in The Lancet Healthy Longevity journal.
Study details
Cognitive decline in older adults in the UK during and after the Covid-19 pandemic: a longitudinal analysis of PROTECT study data
Anne Corbett, Gareth Williams, Byron Creese, Adam Hampshire, Vincent Hayman, Abbie Palmer, et al.
Published in The Lancet Healthy Longevity in November 2023
Summary
Background
Although the long-term health effects of Covid-19 are increasingly recognised, the societal restrictions during the Covid-19 pandemic hold the potential for considerable detriment to cognitive and mental health, particularly because major dementia risk factors—such as those related to exercise and dietary habits—were affected during this period. We used longitudinal data from the PROTECT study to evaluate the effect of the pandemic on cognition in older adults in the UK.
Methods
For this longitudinal analysis, we used computerised neuropsychology data from individuals aged 50 years and older participating in the PROTECT study in the UK. Data were collected from the same participants before the Covid-19 pandemic (March 1, 2019–Feb 29, 2020) and during its first (March 1, 2020–Feb 28, 2021) and second (March 1, 2021–Feb 28, 2022) years. We compared cognition across the three time periods using a linear mixed-effects model. Subgroup analyses were conducted in people with mild cognitive impairment and in people who reported a history of Covid-19, and an exploratory regression analysis identified factors associated with changes in cognitive trajectory.
Findings
Pre-pandemic data were included for 3 142 participants, of whom 1696 (54·0%) were women and 1 446 (46·0%) were men, with a mean age of 67·5 years (SD 9·6, range 50–96). Significant worsening of executive function and working memory was observed in the first year of the pandemic across the whole cohort (effect size 0·15 [95% CI 0·12–0·17] for executive function and 0·51 [0·49–0·53] for working memory), in people with mild cognitive impairment (0·13 [0·07–0·20] and 0·40 [0·36–0·47]), and in people with a history of Covid-19 (0·24 [0·16–0·31] and 0·46 [0·39–0·53]). Worsening of working memory was sustained across the whole cohort in the second year of the pandemic (0·47; 0·44–0·49). Regression analysis indicated that cognitive decline was significantly associated with reduced exercise (p=0·0049; executive function) and increased alcohol use (p=0·049; working memory) across the whole cohort, as well as depression (p=0·011; working memory) in those with a history of Covid-19 and loneliness (p=0·0038; working memory) in those with mild cognitive impairment. In the second year of the pandemic, reduced exercise continued to affect executive function across the whole cohort, and associations were sustained between worsening working memory and increased alcohol use (p=0·0040), loneliness (p=0·042), and depression (p=0·014) in those with mild cognitive impairment, and reduced exercise (p=0·0029), loneliness (p=0·031) and depression (p=0·036) in those with a history of Covid-19.
Interpretation
The Covid-19 pandemic resulted in a significant worsening of cognition in older adults, associated with changes in known dementia risk factors. The sustained decline in cognition highlights the need for public health interventions to mitigate the risk of dementia—particularly in people with mild cognitive impairment, in whom conversion to dementia within 5 years is a substantial risk. Long-term intervention for people with a history of Covid-19 should be considered to support cognitive health.
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