Why Is Social Isolation Among Older Adults Associated with Depressive Symptoms? The Mediating Role of Out-of-Home Physical Activity

BackgroundSocial networks are known to be a key factor associated with late-life depression. However, there is limited knowledge about the pathways linking social isolation to mental health. It has been proposed that health-related behaviors such as physical activity represent one pathway. This study examines the way out-of-home physical activity mediates between social isolation and depressive symptoms in older adults.MethodsA subsample of 334 older adults from the ActiFE Ulm study, Germany, was randomly selected. Older adults (M=72.6years; 60.8% male) were interviewed at baseline and 3years later. Depressive symptoms were assessed using the Hospital Anxiety and Depression Scale (HADS). Social isolation was measured using the Lubben Social Network Scale (LSNS-6). Physical activity was measured by an accelerometer (activPAL) over 1week. To identify out-of-home physical activity, a contemporary physical activity diary classified out-of-home physical activity.ResultsA cross-lagged structural equation model supported an indirect effect (=.014, 95% CI .002 to .039) which means that being socially isolated was associated with lower levels of out-of-home physical activity, and this predicted more depressive symptoms after 3years. However, no direct relationship was observed between social isolation from friends and neighbors at the baseline and depressive symptoms 3years later.ConclusionsUtilizing a longitudinal study design and accounting for reverse causality, this study extends prior work linking social isolation to depression by showing that a variety of neighbor and friendship ties are linked to fewer depressive symptoms by providing occasions for out-of-home physical activity.