The current study supports previous findings that both the EXT PGS and P3 amplitude are significantly associated with externalizing behaviors in COGA, as well as in other samples (Iacono, Malone, & Vrieze, 2017; Karlsson Linnér et al., 2021; Kuo et al., 2021; Porjesz et al., 2005). Findings from the current study are consistent with previous COGA findings that the EXT PGS was significantly associated with an externalizing behavior factor among EA, but not AA, adolescents (Kuo et al., 2021). The association between the EXT PGS and externalizing behavior among EA young adults is consistent with findings from the original paper describing the multivariate GWAS (Karlsson Linnér et al., 2021), and extend the association by also finding a significant association between the EXT PGS and externalizing behavior among AA young adults. Due to the cross-sectional nature of the data, these analyses cannot directly speak to the impact of genetic liability across development; however, the significant associations between the EXT PGS and externalizing behavior among adolescents and young adults suggest that the EXT PGS impacts the expression of externalizing behavior across a wide range of development.
