[i] ePRS significantly outperforms elastic net while achieving comparable standard error across 50 different train-test splits of the target data set. R² represents the proportion of variance in BIS scores explained by the various polygenic scores. ADHD-PRS performs comparably well, potentially owing to R² being driven by a few variants with large effect sizes. (ADHD) Attention-deficit/hyperactivity disorder, (BIS) Barratt impulsiveness scale.