Genetic risk for problematic alcohol use was indexed by constructing genome-wide polygenic scores (PGS), which are aggregate measures of the number of risk alleles that individuals carry weighted by effect sizes from GWAS summary statistics. We used PRS-CSx35 to construct the polygenic scores. PRS-CSx35 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 EA participants, we used discovery sample GWAS summary statistics for problematic alcohol use in individuals genetically similar to reference populations from Europe (ie, EA) from a recent analysis of GWAS meta-analysis of problematic alcohol use36 (COGA removed). For AA participants, we used GWAS summary statistics from a GWAS meta-analysis summary statistics in EA36 in tandem with GWAS summary statistics from recent GWAS meta-analyses of problematic alcohol use in individuals genetically similar to reference populations from Africa (ie, AA)36 (COGA sample removed). Because PRS-CSx improves predictive power for non-European ancestry samples with smaller GWAS,35 we included both the European and African ancestry–derived polygenic scores in the AA sample in COGA,
