Abstract
Background Observational studies have indicated that depression is associated with coronary artery disease (CAD) and myocardial infarction. Nevertheless, causal associations between depression and cardiovascular diseases remain controversial. Hence, we conducted a Mendelian randomization and mediation analysis to evaluate the associations of depression-related genetic variants with CAD and myocardial infarction. Methods and Results Summary statistics from genome-wide association studies of depression (807 553 individuals), and CAD (60 801 cases, including 43 676 with myocardial infarction, and 123 504 controls) were used. We pooled Mendelian randomization estimates using a fixed-effects inverse-variance weighted meta-analysis and multivariable Mendelian randomization. The mediation effects of potential cardiovascular risk factors on depression-CAD and myocardial infarction risk were investigated by using mediation analysis. We also explored the relationship of genetic liability to depression with heart failure, atrial fibrillation, and ischemic stroke. Genetic liability to depression was associated with higher CAD (odds ratio [OR], 1.14; 95% CI, 1.06-1.24; P=1.0×10(-3)) and myocardial infarction (OR, 1.21; 95% CI, 1.11-1.33; P=4.8×10(-5)) risks. Results were consistent in all sensitivity analyses. Type 2 diabetes mellitus and smoking demonstrated significant mediation effects. Furthermore, our Mendelian randomization analyses revealed that the genetic liability to depression was associated with higher risks of heart failure and small vessel stroke. Conclusions Genetic liability to depression is associated with higher CAD and myocardial infarction risks, partly mediated by type 2 diabetes mellitus and smoking. The potential preventive value of depression treatment on cardiovascular diseases should be investigated in the future.