The Relationship between Negative Affect and Alcohol and Marijuana Use Outcomes among Dual Users.

Background: Past research with college students has found that substance use motives, particularly coping motives, mediate the relationship between negative affect and alcohol- and marijuana-related outcomes.
Objectives: This study aimed to investigate substance use motives of dual users of both substances (past 30-day use; not necessarily simultaneous use) and identify any mediation effects that are either common to both substances or substance-specific.
Methods: The majority of dual users (n = 2,034) identified as being White, non-Hispanic (63.8%), female (69.08%), and reported a mean age of 20.24 (SD = 3.16) years. To test study aims, path models were conducted such that negative affect (stress, depressive and anxiety symptoms) were independently modeled as predictors of substance use outcomes (i.e. quantity and consequences) via substance use motives.
Results: All three negative affect symptoms were indirectly related to both alcohol and marijuana consequences via coping motives, such that higher negative affect was associated with higher coping motives; which in turn were positively associated with consequences. Substance-specific effects were also found: (a) stress was indirectly related to both alcohol and marijuana use quantity via enhancement motives, (b) depressive/anxiety symptoms were indirectly related to alcohol use quantity via enhancement motives, and (c) all three negative affect symptoms were indirectly related to both marijuana use quantity and negative consequences via expansion motives. Conclusions: Findings suggests that dual users of alcohol and marijuana with negative affect symptoms engage in substance use for similar reasons as single substance users with negative affect symptoms. Intervention efforts should examine ways to replace substance-related coping and expansion methods with non-substance-related methods.