Transitions in Marijuana Use and Patterns of Reasons for Use during Young Adulthood

Introduction: Marijuana is the most frequently used drug after alcohol, although it remains illegal in the majority of the U.S. and is associated with negative consequences including decreased cognitive ability and addiction. Marijuana users may engage in use for a variety of reasons; understanding these reasons may be key to identifying individuals at risk for escalating use. Recent work has identified patterns of reasons for marijuana use at ages 19/20 and linked patterns to marijuana use and disorder at age 35 (Patrick, Bray, & Berglund, 2016). However, little is known about how individuals may change their reasons for use over time. The current study builds on our recent work by examining transitions in reasons for marijuana use across early young adulthood.

Method. Data from the Monitoring the Future (MTF) study were used. The analysis sample included all participants who had used marijuana in the past year at modal ages 19/20, 21/22, and/or 23/24 (weighted n=7294; 56% female; 79% White, 9% Black, 5% Hispanic, 7% other) because they provided self-reported responses to reasons for use. Latent class analysis (LCA) was used to describe patterns of reasons for using marijuana; a set of thirteen reasons were considered, including social/recreational (e.g., to experiment), coping with negative affect (e.g., to get away from problems), compulsive use (e.g., to get through the day), and drug effect (e.g., to decrease the effects of other drugs) reasons. Then, latent transition analysis (LTA) was used to examine transitions between patterns over time. Covariates were added to explore the extent to which cohort group, gender, race/ethnicity, parent education, grade of first marijuana use, and four-year college attendance predicted transitions.

Results. The 6-class model was selected as optimal. Non-Users (34-41% prevalence) were accommodated at each age (even though they did not respond to reasons) so that individuals could move in and out of use over time. Among users, identified patterns included Experimental Reasons (11-19%), Get High + Good Time Reasons (10-23%), Typical Reasons (11-28%), and Typical + Coping Reasons (10-11%). Members of the Typical Reasons and Typical + Coping Reasons classes showed the highest rates of stability over time. When moving out of the Non-Users class, participants were most likely to transition to the Experimental Reasons class. Additional findings and effects of covariates on class membership and transitions will be discussed. 

Conclusions. These classes of marijuana use reasons suggest distinct profiles underlying marijuana use that persist across young adulthood. Implications for intervention will be discussed and include the need for specific motivational tailoring in efforts to reduce marijuana use and related problems.