Category: Addictive Behaviors

PS7- #B60 - Consequences of Concurrent Marijuana and Alcohol Use

Friday, Nov 17
4:00 PM – 5:00 PM
Location: Indigo Ballroom CDGH, Level 2, Indigo Level

Keywords: Addictive Behaviors | Substance Abuse | College Students

Marijuana (MJ) and alcohol (ETOH) are two substances that are commonly used by young adults in the United States. Previous studies suggest that past-year prevalence rates of MJ doubled over ten years, and the rates of alcohol-use disorder continued to grow during the same time. The increased prevalence is also found in the concurrent use of ETOH and MJ. Concurrent substance use is the ingestion of two or more substances within the same period, so that they interact in an additive or synergistic manner. This could lead to increased risk of experiencing negative consequences, but no studies have examined this relation. This study intends to build on the understanding of ETOH and MJ consequences by examining their relation with concurrent use of these substances.


Data collection is ongoing at a large Midwestern state university, and currently includes 276 students (76.8 % female, 81.5% White) who completed an online survey regarding MJ and ETOH use. Hypotheses include: 1) there will be a significant relation between the frequency of use with amount of consequences experienced; 2) concurrent users will endorse a greater amount of consequences compared to non-concurrent users; and 3) there will be a significant interaction between type of user and frequency of use on consequences experienced, where concurrent users experience greater consequences compared to non-concurrent users. Using linear regression, analyses indicated that the number of days that MJ was used in the previous 30 days was significantly related to the number of consequences experienced in the last 30 days for both concurrent and noncurrent users. Previous 30-day MJ use was also related to a greater number of consequences during a period of heavy MJ use for both concurrent and noncurrent users.  Analyses also indicate that the number of days that ETOH was used in the previous 30 days was significantly related to the number of consequences experienced in the last 30 days for both concurrent and noncurrent users. Previous 30-day ETOH use was also related to the number of consequences during a period of heavy ETOH use for both concurrent and noncurrent users. Analyses indicated that being a concurrent user was significantly related to increased consequences experienced in the last 30 days compared to non-concurrent users. Being a concurrent user was also significantly related to the number of consequences experienced during a period of heavy use compared to non-concurrent users.  When examining the interaction of type of user with MJ and ETOH use, all relations were nonsignificant except for the number of consequences during a heavy period of alcohol use (β = .372, p = .011).


Increased consequences from MJ and ETOH use were related to both the frequency of use, as well as the type of user; however, when examining the interaction of these predictors, only the consequences from heavy periods of alcohol use were significantly related. Furthering the understanding of how substance use is related to consequences, among concurrent substance users, provides insight into the development of substance-related issues.

Joey K. Smith

Colorado State University
Fort Collins, Colorado

Jamie E. Parnes

Colorado State University
Fort Collins, Colorado

Bradley T. Conner

Associate Professor
Colorado State University
Fort Collins, Colorado