Daily associations between cannabis use and alcohol use in young adults: The moderating role of self-report and behavioral measures of impulsivity

Although impulsivity has been implicated in cannabis and alcohol use, its role in alcohol and cannabis co-use behavior use requires further study. We examined the moderating role of self-report and behavioral measures of impulsivity in the daily-level relationships between cannabis use and both (a) likelihood of same-day alcohol use and (b) number of drinks consumed on the same day. Young adults (N=153) completed a 90-day Timeline Follow Back assessing the amount of cannabis smoked (in grams), other forms of cannabis (e.g., oils, edibles), and number of standard drinks consumed each day. Participants also completed a structured interview of Alcohol and Cannabis Use Disorders (AUD/CUD), and both self-report (UPPS impulsivity scales) and behavioral (behavioral disinhibition and delay discounting) measures of impulsivity. Zero-inflated multilevel modelling revealed that negative urgency, delay discounting, and disinhibition were significant, unique moderators of the daily relationship between cannabis and alcohol consumption, after controlling for AUD/CUD symptoms and other covariates. Specifically, individuals high (but not low) on negative urgency and delay discounting showed a positive association between grams of cannabis used on a given day and same-day number of standard drinks consumed. Contrary to expectations, individuals low on negative urgency and low in disinhibition showed a stronger relationship between grams of cannabis consumed and odds of engaging in any drinking on the same day. Results extend research on moderators of within-person, daily-level associations between cannabis and alcohol use, suggesting that several impulsivity-related constructs may contribute to complementary use of cannabis and alcohol among young adults.