While genomic findings for individual psychoactive substances are limited, the identification of genes that explain comorbidity across SUDs and with other externalizing psychopathology has shown some promise. Studies of alcohol, nicotine and drug dependence have found significant associations with SNPs in GABRA2, DRD2/ANKK1 and CNR1. Perhaps the most compelling of these, GABRA2, has also been shown to be associated with several aspects of externalizing behavior, including conduct disorder83 and impulsivity. Thus, GABRA2 may directly influence liability to behavioral undercontrol, which in turn, may increase an adolescent’s likelihood of experimenting with and sustained use of psychoactive substances.
