In this study, we investigated the structure of the shared genetic architecture among externalizing phenotypes and SUDs. To accomplish this, we tested a series of factor analytic models using genomic SEM.18 We further explored the potential differences in genetic architecture between externalizing and SUDs by estimating their genetic correlations with other relevant variables and quantifying the degree of polygenic overlap between externalizing and addiction risk. No models met our criteria for good fit; however, we identified three models with homogeneous, high and stable factor loadings, good reliability and no evidence of concerning model characteristics. We note, however, that the factors in the two-factor models were very highly correlated, suggesting they may not represent meaningfully distinct constructs.
