AUD shares genetic influences with several other common externalizing disorders (e.g., illicit drug dependence and antisocial behavior) and measures of impulsivity [66, 67]. Disinhibition, or the inability to control one’s impulses, is the central feature shared among these disorders [68]. Impulsivity is a multifaceted construct that encompasses diverse behaviors that are poorly planned, inappropriate, or unnecessarily risky [69]. Impulsivity as a whole is likely not tractable for study as an endophenotype because it does not represent a unitary construct unseen to the unaided eye, but specific features, such as the ability to delay rewards (i.e., exhibit self-control) have been proposed as a cognitive endophenotype for AUD and substance use disorders more generally [70]. Delayed reward discounting is heritable [30–51% in an adolescent sample; 71]. Abstinent alcoholics are less likely to delay rewards [72] and the unaffected adult daughters (but not adult sons) of alcoholic fathers are less likely to delay reward [73]. To date, however, there have not been systematic gene identification efforts for sub-clinical impulsivity phenotypes such as delayed reward discounting, and so its potential to aid in gene identification for AUD is still relatively unknown.
