2010), our finding that HR offspring showed increased impulsivity may provide further evidence for the notion that etiological connections exist between impulsivity and alcoholism and other SUDs (for reviews, see Sher and Trull, 1994; Verdejo-Garcia et al., 2008; Dick et al., 2010). In a review, Kamarajan and Porjesz (2012) have outlined electrophysiological abnormalities in impulsivity spectrum disorders, which include AUD and other related disorders. Studies have also shown that psychometrically measured impulsivity, as done in our study, was associated with externalizing disorders in general and substance use disorder in particular (Saunders et al., 1973; O’Boyle and Barratt, 1993; Krueger et al., 2002; Romer et al., 2009). It may be worth noting that prevalence rates of externalizing disorders were significantly higher in the HR group than in the LR group, suggesting that the HR group is susceptible not only to alcoholism but also to other externalizing disorders (see Table 2). Further, our finding of a negative correlation between P3 amplitude and impulsivity scores suggests that individuals with lower P3 amplitudes have higher impulsivity, lending further support to the notion that P3 abnormalities are intrinsically related to impulsivity traits (Justus et al., 2001; McGue et al., 2001; Moeller et al., 2004; Potts
