We created polygenic scores (PGS) from each set of GWAS summary statistics in particpants of primarily European ancestries from two independent cohorts: the National Longitudinal Study of Adolescent to Adult Health [25] (Add Health; N = 5107) and the Collaborative Study on the Genetics of Alcoholism [26] (COGA; N = 7594). Within each sample we created PGS for (1) ALCP-total; (2) EXT; and (3) ALCP-specific using PRS-CS, a Bayesian approach that uses a continuous shrinkage parameter to adjust GWAS summary statistics for linkage disequilibrium (LD) [27].
