Daily Order of Alcohol and Cannabis Use Predicts Drinking Quantity on Simultaneous Use Days, but Substance Use Motives do not Moderate

The present study examined whether using alcohol versus cannabis first when simultaneously using predicts levels of alcohol consumption on a given day, while focusing on daily levels of coping and enhancement motives for simultaneous alcohol and cannabis (SAM) use. Undergraduate student drinkers (n=370) participated in a 14-weekend diary study in Fall 2021, completing surveys on Friday, Saturday, and Sunday mornings (n=2,826 responses) assessing their SAM use, alcohol consumption, and motives for SAM use the previous day. Findings from multilevel models showed that students consumed a greater number of drinks on SAM use days than alcohol-only. Students reported consuming less alcohol on SAM use days when they used cannabis versus alcohol first, and no moderating effects of daily coping or enhancement motives were found. Results suggest that college and university students may not drink heavily on all SAM use days, and students may strategically use cannabis first to reduce their drinking.