Frequency matters: Relations among alcohol and cannabis co-use frequency and alcohol use disorder symptoms in emerging adults.

Emerging adult alcohol and cannabis co-use is on the rise and enacts risk for alcohol misuse/alcohol use disorder (AUD). However, few studies have differentiated whether levels of cannabis use (rather than any cannabis use) moderate between-person risk. Considering low-frequency co-users may use both substances via substitution, low-risk/frequency co-use may not enact the same risk for AUD as higher risk co-use. The present study sought to test this assertion. Public access data on emerging adults from the National Study on Drug Use and Health were used (2002-2019; = 231,681). Participants reported on their past year alcohol use, cannabis use, as well as AUD symptoms. Regression models tested whether levels of cannabis use frequency moderated the association between alcohol use frequency and AUD symptom counts. A significant interaction of cannabis use frequency by alcohol use frequency predicting AUD symptoms was detected. Individuals who co-used alcohol and cannabis reported more AUD symptoms than those who only used alcohol at the same frequency or less. However, co-use was associated with lower AUD symptom counts than alcohol-only use at higher frequency. Findings suggest that all co-users (and alcohol-only users) are not necessarily created equal, and that relations among co-use and risk for AUD symptoms are complex. Rather than a dichotomy of co-users versus alcohol-only users, between-group risk may depend on frequency of both alcohol and cannabis use. (PsycInfo Database Record (c) 2023 APA, all rights reserved).