Intentions matter: How planned and unplanned alcohol and cannabis use influences outcomes.

Objective: An important antecedent of substance use among young adults is intentions for use (e.g., planned vs. unplanned use). In contrast to previous theories, emerging evidence suggests planned use, rather than unplanned use, is primarily related to consumption and sometimes consequences. As this has been most recently investigated with alcohol-only use, there remains a limited understanding of planned versus unplanned cannabis use, as well as how cannabis consumption influences planned versus unplanned alcohol events.

Method: Using data from a 28-day ecological momentary assessment study in young adults (n = 110) that frequently use alcohol and cannabis, we examined how planned versus unplanned alcohol and cannabis use influence consumption levels and consequences while controlling for the impact of each substance on the other.

Results: Alcohol models revealed that planned alcohol use was linked to greater alcohol consumption at the day level and higher likelihood of experiencing positive alcohol consequences at the person level. The use of cannabis on a drinking day was also positively associated with experiencing a positive alcohol consequence. There were no day-level associations between planned alcohol use and negative alcohol consequences. Cannabis models revealed planned use was associated with higher likelihood of experiencing a negative cannabis consequence at the day level but was not associated with cannabis consumption or positive consequences.

Conclusions: This study highlighted differences in planned alcohol and cannabis use in predicting consumption and related consequences in young adults. (PsycInfo Database Record (c) 2025 APA, all rights reserved).