Self-determination theory correlates of cannabis-related outcomes among a large, multi-site sample of college student

Background: Self-determination theory (SDT) is a general theory of human motivation that has been applied to understand why people engage in healthy behaviors. That is, more autonomous reasons for engaging in healthy behaviors is associated with an increased likelihood of initiating and maintaining healthy behaviors. Recent research has shown that this framework is useful for understanding engagement in harm reduction behaviors for alcohol among college students. It stands to reason that this framework may be equally useful for cannabis with the potential to inform intervention efforts for reducing harms associated with unhealthy cannabis use. In the present study, we examined autonomous functioning and psychological need satisfaction per SDT as correlates of cannabis-related outcomes among a large, multi-site sample of college students who use cannabis. Method: Participants were 5497 students recruited from Psychology Department participant pools at 10 universities in 8 states across the U.S (AK, CA, CO, ID NM, TX, VA, WA) who completed an online survey for partial course credit. We restricted analyses to those who reported consuming cannabis at least once in the past month (n=1398, about one-fourth of the total sample). The analytic sample was 20.25 years of age on average (SD=3.88) and mostly female (68.9%) and non-Hispanic white (59.4%). Participants completed measures assessing the three facets of autonomous functioning (authorship, interest-taking, and susceptibility to control) and satisfaction and frustration of the psychological needs for autonomy, competence, and relatedness, as well as a variety of measures assessing cannabis-related outcomes, including severity of use (i.e., Cannabis Use Disorder Identification Test [CUDIT]), negative consequences (i.e., Marijuana Consequences Questionnaire [MACQ]), and harm reduction behaviors (i.e., Protective Behavioral Strategies for Marijuana [PBSM]). Results: Consistent with hypotheses, overall autonomous functioning was positively correlated with PBSM (r=.179, p<.001) and negatively correlated with CUDIT (r=-.160, p<.001) and MACQ (r=-.092, p=.017). Separating autonomous functioning by subscale (i.e., domain), the correlations were largest in magnitude for the authorship domain (r=.250, r=-.240, and r=-.168, respectively, p<.001). Also consistent with hypotheses, greater satisfaction of each psychological need was positively correlated with PBSM (.149<rs<.203, ps<.001) and negatively correlated with CUDIT (-.146<rs<-.120, ps<.01) and MACQ (-.171<r<-.132, ps<.01); generally, these correlations were largest in magnitude for relatedness satisfaction. In contrast, greater frustration of each psychological need was negatively correlated with PBSM (-.144<rs<-.121, ps<.001) and positively correlated with CUDIT (.199<rs<.229, ps<.001) and MACQ (.133<rs<.215, ps<.01); the correlations were largest in magnitude for relatedness frustration with PBSM and competence frustration with CUDIT and MACQ. Conclusions: The present study is the first to demonstrate that higher autonomous functioning and greater psychological need satisfaction are protective factors for cannabis-related outcomes, including less consumption, fewer negative consequences, and more frequent use of harm reduction behaviors. SDT provides a rich framework for understanding not only why college students may engage in healthy cannabis-related behaviors, but also the conditions that foster that engagement, making it an ideal theory to inform cannabis interventions. The present findings warrant replication but suggest promise for SDT as a framework for understanding cannabis-related outcomes that future research should investigate further.