The effect of the COVID-19 pandemic on the general population has been catastrophic. Despite substantial progress in understanding the virology, transmission, and pathogenesis of SARS-CoV-2, many of the long-term consequences of COVID-19 or the restriction measures implemented around the world remain unknown. Evidence for the associated adverse effects of isolation, loneliness, post-traumatic stress, depression, fear, anger, and confusion is overwhelming. However, changes in cognitive and physical functioning due to the COVID-19 pandemic have been less well documented.
Anne Corbett and colleagues used longitudinal data from the PROTECT study to evaluate the effect of the pandemic on cognition in older adults in the UK, exploring various factors associated with changes in cognitive functioning. The use of computerized neuropsychological data collected before the pandemic and during its first and second years enabled repeated measures to be obtained for the same individuals across the pandemic. Declines in executive function and working memory were observed across the whole cohort in the first year of the pandemic, including in subgroups of individuals with mild cognitive impairment or a history of COVID-19, and the decline in working memory continued into the second year of the pandemic. Although initially thought to cause acute respiratory symptoms, the effects of SARS-CoV-2 on other systems—including the central and peripheral nervous system—is becoming increasingly clear. 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. This study also highlights reduced exercise, alcohol use, depression, and loneliness as key risk factors that affected the rates of cognitive decline in the older population during the COVID-19 pandemic. The study was observational in nature and therefore causality cannot be inferred, but it would be of interest to elucidate some of the potential biological mechanisms involved in these associations.