The IVW method also identified evidence for associations of genetically-predicted depression and lifetime smoking index (ORDep-Smk = 1.09, 95% CI: 1.06–1.13, p < 0.001), and between genetically-predicted CRP levels and lifetime smoking index (ORCRP–Smk = 1.03, 95% CI: 1.02–1.05, p < 0.001) (Supplementary Table 3). Here, CRP is linked to depressive disorder.