Temporal relationship between depression and dementia – findings from a large community-based 15 year follow-up study

Context—Late-life depression is associated with increased risk of dementia but the temporal relationship between depression and development of dementia remains unclear. Objectives—To examine the association between risk of dementia and 1) baseline depressive symptoms; 2) past history of depression, particularly early-life (< 50 years) versus late-life depression; and 3) individual domains of the Center for Epidemiologic Studies Depression Scale (CESD). Design—A large cohort with initially non-demented participants was followed biennially for up to 15 years for incident dementia. Baseline depressive symptoms were assessed using the 11-item version of CESD (CESD-11), and defined as CESD-11 score ≥ 11. Self-reported history of depression was collected at the baseline interview. Cox proportional hazards regression was used to assess the association between depression and the dementia risk. Setting—Population-based cohort drawn from members of Group Health Cooperative in Seattle, Washington. Participants—A cohort of 3,410 participants without dementia aged ≥ 65 years