College students with lower psychological need satisfaction were more likely to use alcohol and marijuana simultaneously, primarily to cope with stress — and this pattern was strongest among students who expected positive effects from combining the substances.
College health professionals, counseling center staff, substance use prevention program designers, and addiction researchers.
What the researchers found
Lower psychological need satisfaction predicted greater simultaneous alcohol-marijuana (SAM) use through calm/coping and social motives, with the coping pathway strengthened among students with higher positive SAM expectancies, suggesting a vulnerability profile for co-use.
Why it matters
Understanding that unmet psychological needs drive co-use through coping motives — especially when amplified by positive expectations — identifies specific intervention targets for reducing risky substance combinations on college campuses.
The numbers in context
N=822 from 6 universities; 70.2% female; mean age 19.44; coping and social motives mediated PNS→SAM use; moderation significant for coping motives with positive expectancies; predominantly White non-Hispanic (62.9%)
How the study worked
Cross-sectional survey of 822 college students from six US universities who reported past-month SAM use, using moderated mediation models testing psychological need satisfaction, SAM motives (calm/coping, social), and positive SAM expectancies.
What this study cannot tell us
Cross-sectional design limits causal inference; self-selected sample of SAM users; predominantly White and female; self-report measures; university sample may not generalize; doesn't capture actual consumption quantities.
How to read the evidence
Multi-university sample with theoretically grounded mediation analysis, but cross-sectional design and self-selected sample limit causal and generalizability claims.
When this study was published
Published 2026; reflects current college substance use patterns.
The bigger picture
Rather than just telling students not to mix substances, this research suggests that addressing underlying psychological needs and challenging positive expectancies could be more effective prevention strategies.
Questions still open
- Would interventions addressing psychological need satisfaction reduce SAM use? Are coping motives for SAM use different from single-substance coping use? Do these pathways differ across cultures or non-college populations?
Common questions
Why do college students mix alcohol and marijuana?
What makes some students more likely to co-use?
Read the original research
Psychological Need Satisfaction and Simultaneous Alcohol and Marijuana Use: A Moderated Mediation Model of Expectancies and Motives.
Substance use & misuse, 61(4), 483-490
Citation
Herchenroeder, Luke; Krishnamurti, Harini; Dodge, Tonya; Yeung, Ellen. (2026). Psychological Need Satisfaction and Simultaneous Alcohol and Marijuana Use: A Moderated Mediation Model of Expectancies and Motives.. Substance use & misuse, 61(4), 483-490. https://doi.org/10.1080/10826084.2025.2565421