The common co-occurrence of behavioral disinhibition, substance use disorders, antisocial behavior, and conduct problems reflects a broad dimension of psychopathology termed the externalizing spectrum (Krueger et al., 2002). Externalizing disorders are associated with poor mental health outcomes, premature death (Eaton et al., 2013; Odgers et al., 2007) and are estimated to cost more than 417 billion dollars annually in the United States alone (National Institute on Drug Abuse, 2015). Twin studies have repeatedly found that externalizing phenotypes are highly heritable across different developmental periods and point to behavioral disinhibition as a common feature uniting externalizing disorders (Tarter et al., 2003; Young et al., 2009; Krueger and Markon, 2006). The goal of this study was to identify neural phenotypes of externalizing by investigating associations between measured genetic risk for externalizing disorders and brain networks. Based on growing evidence that connectivity in resting-state functional networks reflects heritable differences in brain organization and function (Glahn et al., 2010; Smit et al., 2008), we examined patterns of resting-state connectivity as plausible heritable neural phenotypes for externalizing.
