Background and purpose. The literature supports depression as an independent risk factor for morbidity and mortality from cardiovascular diseases. Depression has been found to be a risk factor for coronary heart disease, and possibly may also be a risk factor for stroke. The present research aimed to: (1) provide a systematic review of the literature investigating the prospective association between depression and stroke; (2) determine the relationship between depression and incidence of stroke in a cohort of older adults; and (3) examine the role of inflammation in the relationship between depression and stroke.
Methods. Studies were identified by searching electronic databases. Inclusion and exclusion criteria were defined and applied by two independent researchers. Data were combined using fixed and random effects for meta-analysis. We investigated the prospective association between depression and stroke using 5,639 older adults participants of the Cardiovascular Health Study. Cox proportional hazards model were used to evaluate the association between baseline depression and incidence of stroke. We used a time-dependent model to evaluate the change of depression over time as a predictor of stroke. The mediator role of inflammation was evaluated using stratification analyses and extension of Cox regression models.
Results. As part of the metaanalysis we identified 5 cohort studies. When combined using a random effects model the estimate was 1.6. Our prospective analysis demonstrated a positive association between depression and stroke. The change in depression over time was a strong predictor of stroke even after adjusting for depression at baseline. Inflammation was not a mediator in the association between depression and stroke. There was some evidence that inflammation acted as a moderator for this relationship.
Conclusions. Research to date supports a positive relationship between depression and stroke. Depression is a treatable medical condition, and its detection and treatment could have an important effect on vascular diseases (cardio- and cerebro-vascular), two of the leading causes of mortality in USA. The role of inflammation could be considered as a moderator instead of a mediator. Future research should concentrate on identifying underlying mechanisms in addition to inflammation that explain the excess risk for cardiovascular disease related to depression.