When considering the number of shared loci as a proportion of the total polygenicity of ADHD, the vast majority of variants influencing ADHD were also estimated to influence the other investigated psychiatric disorders (84%–98%; Fig. 2, Supplementary Fig. 11, and Supplementary Table 19). While the fraction of concordant variants (within the shared part) with ASD and MDD was at the high end (75–76%), it was lower for SCZ (59%). When considering other phenotypes, insomnia demonstrated the smallest overlap with ADHD in terms of actual number of variants (4.5K, s.d. = 1,281; 62% of ADHD variants shared), while almost all variants influencing ADHD also influence educational attainment, age at first birth and smoking (Fig. 2 and Supplementary Table 19). For insomnia and smoking, 83% and 79% of shared variants had concordant directions, respectively, while only 21% and 20% of ADHD risk variants were concordant with educational attainment and age at first birth associated variants, respectively (Supplementary Table 19).
