Alcohol and cannabis are two of the most commonly used substances among college students. Recently, a growing number of young adults have begun using alcohol and cannabis simultaneously. Simultaneous alcohol and cannabis use (SAM) has been associated with a variety of adverse effects including academic issues, social effects, and passing out. The order of substance use in SAM users has also been shown to influence that amount of substances consumed. This study examines substance use behaviors among SAM users.

The study’s sample consisted of 284 college students who indicated use of cannabis and alcohol during the past year. Participants completed web-based surveys that assessed alcohol use, cannabis use, and SAM use. Students were also asked to report the type of cannabis used on each occasion and consequences on the morning following the day of substance use. Data was analyzed using latent class analysis (LCA) to classify SAM users based on seven different latent class indicators of use behaviors.

Results of the data analysis indicated five-class models of SAM users. The first category was the Frequent Cannabis-Focused SAM class (21%) which was characterized by a high estimated blood-alcohol content (eBAC), multiple forms of cannabis used, two or more same-day consequences, cannabis on non-SAM days, and SAM use on three or more days. The second category was Frequent Alcohol-Initiating SAM class (29%) which was similar to the first category expect they typically began SAM days with alcohol and drank excessively on non-SAM days. The Heavy-Drinking Infrequent SAM class (12%) had a high eBAC, multiple same-day consequences, initiated SAM days with alcohol, and heavily drank on non-SAM days. However, they engaged in SAM 1-2 times. The Moderate-Drinking Infrequent SAM class (29%) was similar to the previously described class but did not have a high eBAC. Lastly, the Light-Drinking Infrequent SAM class (9%) reported 1-2 SAM days and no consequences of substance use. Men were more likely to be classified as Frequent-Cannabis Focused and Moderate SAM compared with Frequent Alcohol-Initiating SAM and Heavy-Drinking Infrequent SAM.

Takeaway: College students who engage in simultaneous alcohol and cannabis use present with a variety of substance use behaviors which can impact risk of negative consequences.

Lanza, S.T., Sokolovsky, A.W., Linden-Carmichael, A.N., White, H.R., Jackson, K.M.. Understanding Heterogeneity Among Simultaneous Alcohol and Marijuana Users: Latent Classes Derived From Daily Diary Data. Journal of Studies on Alcohol and Drugs. 2022;83(3):358-363.