The data in Table 3 support Hypothesis 5 (combined diagnoses will be associated with more alcohol and drug use and problems than will be seen with either AUDs or SUDs alone). Even in this prospective study of men at high risk for AUDs, the development of combined AUDs and SUDs was associated with heavier substance use and more alcohol and drug problems over the 30 years for men in Group 1 compared to Groups 2 or 3. This result was observed despite similar ages, racial distributions, education, religious involvement, as well as alcohol and drug histories at T1 for Groups 1 and 3. The course of combined diagnoses might reflect the impact of concomitant substance use itself, perhaps through greater impaired judgment, poor executive functioning and problems in mood regulation associated with the exposure to multiple types of substances (Casper et al., 2010; Tait et al., 2011).
