Abstract 12976: Clinical Depression Substantially Increases the Risk of Future Ischemic Stroke

Abstract

Introduction Depression has shown to be an independent risk factor of future ischemic stroke by numerous studies. The proposed biological mechanisms linking these two disorders include excessive platelet activity, mechanisms of stress response, and inflammatory mechanisms. Most former studies have investigated the association with subclinical depressive symptoms at a single time point. Moreover, many studies have included CVD cases at baseline, and thus included the potential for reverse causality. In our study we examined the effect of clinical depression on risk of ischemic stroke morbidity and mortality. Change in depression status over time was incorporated by using time varying covariates. All prevalent CVD cases were excluded, to reduce the possibility of reverse causality. Hypothesis We assessed the hypothesis that clinical depression is associated with increased risk of ischemic stroke, independent of several well established stroke risk factors. Methods Material from the Twingene population has been used, which is a large population-based study on Swedish elderly twins. Twingene has been linked to the Swedish national patient register and the cause of death register. After excluding all CVD cases at baseline, 11417 individuals remained in the study population and were included in the statistical analyses. In total, 481 depression cases and 381 stroke events could be identified. Cox regression was carried out, days since study entry was used as the underlying time scale. Covariates included in the fully adjusted model were; age, gender, atrial fibrillation, HDL, self-reported diabetes, systolic blood pressure and smoking status. Separate analysis using all-cause mortality as the outcome was also performed. Results In the fully adjusted model, clinical depression was associated with an increased risk of ischemic stroke (hazard ratio=2.23, p-value<0.01). Clinical depression was also associated with all-cause mortality in the fully adjusted model (hazard ratio=1.54, p-value=0.045). Conclusions We found evidence that clinical depression is an independent risk factor for stroke. The findings suggest that depressed patients should be monitored more closely for stroke symptoms. We believe our findings merit further investigations.