Regarding Hypothesis 4 (combined diagnoses will relate to the items that predict AUDs plus those that predict SUDs), there were few unique earlier life correlates of combined diagnoses, and the predictors of Group 1 reflected items that related to AUDs alone and SUDs alone. One important caveat regarding this conclusion, however, relates to the differences across Groups 1, 2, and 3 regarding the performance of Novelty Seeking, Sensation Seeking, and Impulsivity, as these externalizing characteristics are not homogenous (Courtney et al., 2012). Additional study is needed to explore the possibility that the different scores on these questionnaires across Groups 1-3 may have clinically relevant implications.
