IL6 and depressive symptom measurement: Several putative biological mechanisms have been proposed to explain the bidirectional association between depression and CVD, including autonomic nervous system dysregulation30; platelet receptor and function change31; inflammatory biomarkers such as interleukin-6, tumor necrosis factor-alpha, CRP, or coagulation factors32; endothelial dysfunction; and genetic variation of the serotonin transporter33.