S100B and major depressive disorder: We applied two-sample MR methods on the recently published large-scale GWAS for blood S100B levels measured 5-7 days after birth (N = 8138; the iPSYCH dataset) [29] and in an older adult sample (mean age: 72.5 years; N = 769; the Lothian dataset) [30, 31] as exposure, and case-control GWAS for SCZ (N = 79,845) [2], BIP(N = 51,710) [3], MDD(N = 500,199) [32], ASD(N = 46,350) [7], AD(N = 63,976), and Parkinson’s Disease (PD) (N = 482,730) [33] as outcomes.