The current study sought to determine the associations between known genetic contributors and a specific neural risk factor, the visual oddball task related target P3, for a broad liability for externalizing behaviors within adolescents and young adults. We found support for Hypothesis 1, that the EXT PGS was positively associated with the externalizing behavior score in young adults and EA adolescents. Hypothesis 2 was partially supported such that blunted P3 amplitude was associated with increased externalizing behavior scores; however, this was only significant among EA young adults. Hypothesis 3 – that higher EXT PGS would be associated with lower P3 amplitude – was also supported, but again, only among EA young adults. Lastly, we did not find evidence that P3 amplitude accounted for the association between the EXT PGS and externalizing behavior (Hypothesis 4). P3 amplitude was not significantly associated with the EXT PGS and the two variables were statistically independent in analyses where they were both included in the same regression model. The present study adds to the literature in advancing the understanding of the mechanisms through which genetic liability is, and is not, conferred for externalizing behaviors.
