Association of social isolation and smartphone use on cognitive functions

Background: The number of socially isolated older adults has increased owing to the coronavirus disease pandemic, thus leading to a decrease in cognitive functions among this group. Smartphone use is expected to be a reasonable preventive measure against cognitive decline in this social context. Thus, this study aimed to investigate the influence of social isolation and smartphone use on cognitive functions in community-dwelling older adults.Methods: We divided 4,601 community-dwelling older adults into four groups based on their levels of social isolation and smartphone use. Then, we conducted cognitive functions tests including a word list memory task, trail-making test, and symbol digit substitution task. Social isolation was defined when participants met two or more of the following measures: domestic isolation, less social contact, and social disengagement. We used an analysis of covariance adjusted by background information to measure between-group differences in levels of cognitive functions and social isolation. A linear regression model was used to analyze the association of standardized scores of cognitive function tests with smartphone use.Results: Smartphone users' scores of the symbol digit substitution task were superior compared with both nonusers with social isolation and without. All cognitive functions were associated with smartphone use among non-socially and socially isolated participants. Socially isolated older adults showed an association only between trail making test-part A and smartphone use. Conclusions: Smartphone use was associated with cognitive functions (memory, attentional function, executive function, and processing speed) even in socially isolated community-dwelling older adults.