Recognizing these complexities, studies of AUDs often evaluate multiple genes that might contribute to genetically-influenced characteristics, or endophenotypes (Gottesman and Gould, 2003), to help dissect a complex phenotype into relatively independent etiological components. Among the many genetically-influenced characteristics that relate to alcohol problems (Kendler et al., 2003; Reilly et al., in press), COGA has emphasized the importance of impulsivity in part because many of the original COGA subjects were recruited from public institutions where patients are more likely to have elevated levels of impulsivity. We have also emphasized the low level of response (low LR) to alcohol as a reflection of the long-standing interest by some COGA investigators in AUD risks related to how a person responds to alcohol (Dick et al., 2013; Schuckit et al., 2001; Sher et al., 2005; Wardell et al., 2015).
