The distribution of significant odds-ratios of the OR models presented in Table 5 revealed that the risk of abuse/dependence in young adulthood was elevated once a person had used any substance at least once. For instance, the likelihood of developing a lifetime diagnosis of an alcohol SUD at Wave 2 was at least two times greater when comparing persons who experimented with alcohol, tobacco, or marijuana in adolescence to persons who abstained (OR model), and at least eight times greater if they were dependent on tobacco as opposed to being abstinent. More importantly, correcting for involvement with other substances during adolescence revealed significant relationships within and between substances across all three Wave 1 comparisons. For example, use or dependence on tobacco during adolescence elevated the likelihood of not only tobacco dependence in young adulthood but also alcohol and marijuana problems. It is important to note that, among statistically significant findings, the comparison between the odds-ratios of the OR and the AOR models revealed minor differences between the models, providing strong evidence of a common or shared liability between the substances.
