Background: Social relations and depressive symptoms are intertwined. They both predict subsequent dementia, but only few studies on the association between social life aspects and subsequent dementia exist.
Methods: The risk of subsequent dementia was estimated over 2 follow-up assessments, each 18 months apart, depending on leisure activity, social support (general scale and the 3 factors emotional support, practical support, and social integration), and depressive symptoms, using proportional hazard models in a cohort of elderly patients (n = 2,300, with a mean age of 82.45 years) recruited for the study by their general practitioners.
Results: Higher depressive symptoms and lower cognitive and physical activity were associated with an increased risk of subsequent all-cause dementia and Alzheimer's dementia (AD). While neither social engagement nor the general social support scale was associated with subsequent dementia, a higher level of social integration was associated with a lower dementia risk. In combined models, the results for activity variables remained similar, but the strength of the association between depressive symptoms and the subsequent risk of dementia decreased, and the association with social integration disappeared.
Conclusions: Depressive symptoms increased and activity variables decreased the risk of subsequent dementia; however, activity variables, namely cognitive and physical activity, partly mediated the effect of depressive symptoms on the subsequent risk of all-cause dementia and AD. In many cases, social support was not associated with a risk of subsequent dementia.
Keywords: Alzheimer's dementia; Cognitive activities; Dementia; Depressive symptoms; Emotional support; Physical activities; Practical support; Social engagement; Social support.