Moderated mediation of physical activity through depression on the relationship between loneliness and cognitive function in older adults

OBJECTIVES: This study examined the mediating effects of depression on the relationship between loneliness and cognitive function. It also aimed to test whether this mediating effect varied with the level of physical activity. METHOD: Data were obtained from the English Longitudinal Study of Aging (ELSA) and responses of 3,537 adults aged 65 years or older were analyzed. RESULTS: Analysis using the PROCESS Macro 7 model showed that loneliness had a negative effect on cognitive function. Also, the mediating effect of depression on the association between loneliness and cognitive function and the moderated mediating effect of physical activity were significant. That is to say, loneliness influenced cognitive function decline mediating depression, and the mediating effect of depression varied according to the level of physical activity. CONCLUSION: This study revealed the psychological mechanism by which loneliness influences cognitive decline in older adults, and suggests that physical activity can be a preventive and therapeutic intervention for cognitive decline.