Genetic risk for alcohol problems was indexed by constructing genome-wide polygenic risk scores (PRS), which are aggregate measures of the number of risk alleles individuals carry, weighted by effect sizes from GWAS summary statistics. We used PRS-CSx (Ruan et al., 2022) to construct the polygenic scores. This approach uses ancestry-specific discovery sample GWAS weights, paired with linkage disequilibrium information from an ancestry-matched external reference panel, to estimate the posterior effect size for each SNP. For participants of European ancestry, we used discovery sample GWAS summary statistics for alcohol problems in individuals of European ancestry from a recent meta-analysis of GWAS weights from the Psychiatric Genomics Consortium (PGC) DSM-IV alcohol dependence analyses (COGA sample removed; Walters et al., 2018), the UKBiobank AUDIT-P analyses (Sanchez-Roige et al., 2017), and the Million Veteran Program (MVP) alcohol use disorder analysis (Kranzler et al., 2019; Zhou et al., 2020). For participants of African ancestry, we used GWAS summary statistics from a meta-analysis of the European ancestry in tandem with GWAS summary statistics from the PGC DSM-IV alcohol dependence analyses (COGA sample removed; Walters et al.,
