In a recent study published in The Lancet Healthy Longevity, researchers assessed the effects of the coronavirus disease 2019 (COVID-19) pandemic on the cognition of older adults in the United Kingdom (UK).
Concerns have emerged about the neuropsychological effects of social restrictions imposed during the COVID-19 pandemic, which are particularly relevant for older adults. Social restrictions have reduced networking and contact, and social isolation has been associated with loneliness. Some studies have established links between COVID-19 and cognitive effects. Nevertheless, the impact of the pandemic per se on cognition is less clear.
Study: Cognitive decline in older adults in the UK during and after the COVID-19 pandemic: a longitudinal analysis of PROTECT study data. Image Credit: Lightspring / Shutterstock
About the study
The present study investigated the effects of the COVID-19 pandemic on older adults’ cognition in the UK. The researchers used data from the PROTECT study initiated in 2015 that collected data throughout the pandemic. Specifically, data from the year before the pandemic and the first and second pandemic years were analyzed.
Participants were at least 50 years old at the time of data collection and were not diagnosed with dementia. At baseline, demographic data, such as age, sex, education level, and ethnicity, were collected. Subjects completed cognitive tests, such as verbal reasoning, paired associated learning, self-ordered search, and digit span tests.
Cumulative scores from digit span, self-ordered search, and paired associate learning tasks served as the composite measure for working memory. Participants took the tests at each annual time point. Further, annual questionnaires were administered to obtain health-related data. The patient-health questionnaire was used to assess depression. Loneliness was examined using a broader questionnaire on mental health.
Data on the frequency of physical activity and alcohol consumption were obtained. Using cognition score as the outcome, timepoint as the explanatory variable, and sex and age as covariates, a linear mixed-effects model was constructed. In sensitivity analyses, people with cancer or Parkinson’s disease were excluded, and the change in cognition in the first pandemic year was compared with that in the second year.
Additionally, the primary analysis was repeated on two sub-groups – participants with mild cognitive impairment and those with a past COVID-19 diagnosis. Hierarchical multivariable regression was used in the sub-analysis of individual cohorts (overall cohort and two sub-groups) to examine associations of altered cognition.
Findings
Neuropsychological data from the PROTECT study were available for 3,142 individuals at the pre-pandemic time point. Of these, 10% and 13.6% did not provide data for the first and second pandemic years, respectively. The pre-pandemic trajectories did not significantly differ between those who completed assessments during the pandemic and those who did not.
Cognitive performance analysis revealed a significant worsening of working memory and executive function in the first pandemic year. The effect on working memory persisted in the second year. When people with a COVID-19 history or mild cognitive impairment were excluded, the differences in working memory and executive function were still significant between the pre-pandemic year and the first pandemic year. Participants showed a higher rate of cognitive changes during the pandemic than before.
Executive function and working memory in the whole cohort decreased by an average of 0.61% and 0.64% in the pre-pandemic year but by 1.24% and 1.16% during the pandemic, respectively. This higher rate of decline in the pandemic was also evident in both sub-groups. Depression and loneliness in people with mild cognitive impairment were associated with cognitive decline, and depression was associated with cognitive decline in the COVID-19 sub-group in the first pandemic year.
In the second pandemic year, reduced exercise frequency was the only factor affecting executive function in the whole cohort. Nevertheless, higher alcohol consumption, depression, and loneliness were associated with poor working memory in the mild cognitive impairment group in the second year. Likewise, in the COVID-19 sub-group, associations were observed between working memory and reduced exercise frequency, depression, and loneliness.
Conclusions
The study revealed an accelerated decline in executive function and working memory in older UK adults in the first pandemic year. Nevertheless, the worsening of working memory was sustained during the second year, when restrictions were lifted. The magnitude of cognitive change was notable, with over 50% higher decline in executive function and working memory.
Sub-group analysis similarly indicated the same effect but more rapid and pronounced cognitive decline than the overall cohort. Moreover, the analysis also highlighted associations between alcohol intake, depression, loneliness, and physical activity with cognitive decline during the pandemic. As such, it is necessary to address these changes in lifestyle behaviors. The researchers speculate that interventions for these (lifestyle) behaviors could benefit cognition.