This project is marked by four notable limitations. First, due to limited availability of GWAS summary statistics and technical issues involved with including multiple ancestries in a single genomic SEM model, our analyses are limited to individuals of European ancestries. Second, we note that none of our models met our preregistered criteria for good fit. One explanation for this is the use of residual correlations in the original externalizing model, which were excluded from the main analyses here, but in sensitivity analyses were shown to improve model fit substantially. Third, our model does not account for other sources of genetic variance (e.g., internalizing and thought disorders) shared among externalizing and SUD phenotypes and which may contribute to the increased overlap among these phenotypes. These sources of variance may be especially important, given evidence that the addiction risk and externalizing factors are differentially associated with internalizing and thought disorder psychopathology. Finally, the definitions of cases in the GWAS used in this study include any person who meets criteria for the relevant diagnosis without regard to comorbid conditions for which they may
