The general similarity among the probands regarding baseline demography and psychiatric histories facilitated our ability to focus on the impact of several genetically-influenced intermediate phenotypes that relate to the risk for SUDs and/or AUDs (Schuckit, 2009). Regarding Hypotheses 2 (externalizing and internalizing characteristics will predict both AUDs and SUDs), in Tables 1 and 2, while the four outcome groups did not differ greatly on internalizing problems, higher scores on externalizing traits were related to SUDs, AUDs, and combined diagnoses. The fact that the externalizing questionnaires had not been measured at T1, but were evaluated at T10 or T15, means that we can only describe associations of these scores with the four outcomes, although the trait nature of the measures implies a possible causal relationship.
