Depression, Vascular Factors, and Risk of Dementia in Primary Care: A Retrospective Cohort Study

ObjectivesTo study the interaction between and timing effects of depression and vascular disorders on dementia risk. DesignRetrospective cohort study. SettingPrimary care practices in the south of the Netherlands. ParticipantsIndividuals in primary care aged 50 to 100 followed for 13years (N=35,791). MeasurementsMedical diagnoses of incident depression, hypertension, obesity, type 2 diabetes mellitus, stroke, and dementia were extracted from a research database. Cox proportional hazards regression was used to test whether incident depression predicted dementia and its putative interactions with vascular factors. ResultsIn total, 1,680 participants developed dementia. Individuals with depression (n=978) had a higher risk of dementia (adjusted hazard ratio (HR)=2.03, 95% confidence interval (CI)=1.56-2.64). Depression exerted most effect in participants with incident stroke (HR=5.29, 95% CI=2.52-11.14) or newly diagnosed hypertension (HR=3.09, 95% CI=1.54-6.20). ConclusionDepression in later life increases the risk of dementia. The effect is particularly high in individuals with depression and vascular disorders. Targeting late-onset depression in individuals with vascular disorders might lower dementia risk by preventing cerebrovascular changes.