The current study had several methodological strengths. Our use of multiple informants in the factor model of impulsivity and sensation seeking increased confidence in the findings because associations were likely not due to informant bias. We utilized longitudinal data to prospectively predict change in externalizing outcomes over 18 months. This allowed us to establish the directionality of the effect from disinhibition to externalizing outcomes and assess the role of the SNP on behavior change. We also tested these models without controlling for T1 externalizing symptoms to ensure that genetic effects were not weakened by predicting change in externalizing problems, especially because T1 and T2 externalizing problems were moderately stable. Our use of a high-risk sample likely more clearly illuminated the pathways of interest due to greater variability in study constructs. In addition, to reduce the possibility of false-positive findings, we tested only theoretically driven associations, examined only one SNP based on biological and theoretical reasoning, included covariates, and corrected for multiple testing. Furthermore, this particular SNP has been widely studied and many of our results replicated prior findings.
