Characterizing alcohol consumption and positive and negative consequences during simultaneous alcohol and cannabis use events (2024)

OBJECTIVE: Young adults who engage in simultaneous alcohol and cannabis use report heavy use of both substances. Event-level studies examining differences between consequences experienced on simultaneous use compared with single substance use days have been mixed. Although studies often control for alcohol use levels, few have examined how quantity of alcohol may influence consequences experienced on simultaneous use days. Furthermore, little research has examined the relationship between simultaneous use and positive consequences or explored individual consequences. This study examined differences in consequences experienced on simultaneous use versus single substance use days (alcohol-only, cannabis-only) including endorsement of specific consequences and examined the relationship among simultaneous use, consequences, and alcohol consumption.
METHOD: Young adults who engage in simultaneous use (N = 86) completed 30 days of daily surveys reporting substance use and positive and negative consequences.
RESULTS: Simultaneous use days were associated with more negative and positive consequences than single substance use (alcohol-only and cannabis-only) days. We also examined endorsement of specific positive and negative consequences on alcohol-only, cannabis-only, and simultaneous use days. The effect of day type (simultaneous use vs. alcohol-only) on consequences was moderated by alcohol quantity. On lighter drinking days, more positive and negative consequences were endorsed if it was a simultaneous use versus alcohol-only day. On heavier drinking days, number of consequences did not differ between simultaneous use and alcohol-only days.
CONCLUSIONS: Findings from this study point to simultaneous use as both reinforcing and high risk and highlight the importance of intervening even on lighter drinking simultaneous use occasions to reduce harms.