Not All Days of Using Alcohol and Cannabis Together Are Equal
Simultaneous alcohol-cannabis use days fall into four distinct patterns, with 'Heavy Use' days (14%) carrying the most harm — simply knowing someone co-uses isn't enough information.
Quick Facts
What This Study Found
Multilevel latent class analysis of 1,527 simultaneous use days identified four patterns: Alcohol-Focused (43%), Cannabis-Focused (35%), Heavy Use (14%), and Early-Day Use (8%). Heavy Use days were most strongly linked to same-day harms. Day-level patterns varied significantly across three motives: being social, being offered, and having fun.
Key Numbers
255 participants, 1,527 simultaneous use days. Four patterns: Alcohol-Focused (43%), Cannabis-Focused (35%), Heavy Use (14%), Early-Day Use (8%). Heavy Use days significantly more harmful than other day types.
How They Did This
Multilevel latent class analysis of daily survey data from 255 college students who completed up to 54 days of surveys, yielding 1,527 person-days with simultaneous alcohol-cannabis use. Both within-person and between-person variation was modeled.
Why This Research Matters
Research on co-use has treated all simultaneous use days as equivalent, but this study shows they're not — identifying which types of days are dangerous can help target interventions more precisely.
The Bigger Picture
This granular, day-level approach to understanding substance use represents a shift from asking 'how often do you use?' to 'what kind of using day was it?' — a distinction that could revolutionize personalized harm reduction.
What This Study Doesn't Tell Us
College student sample limits generalizability. Self-reported daily data subject to recall issues. 54-day period may not capture seasonal or event-driven patterns. Cannot determine causation between day type and harms.
Questions This Raises
- ?Can real-time interventions (like text messages) be triggered when someone is having a 'Heavy Use' day pattern?
- ?Do day-type patterns predict longer-term outcomes?
- ?Would non-college populations show similar patterns?
Trust & Context
- Key Stat:
- Evidence Grade:
- Innovative daily-level methodology with adequate sample, limited by college-specific population and self-reported data.
- Study Age:
- Published 2026, using intensive daily survey methodology.
- Original Title:
- Heterogeneity of Within-Day Simultaneous Alcohol and Cannabis Use Behaviors Among Young Adults: A Multilevel Latent Class Analysis.
- Published In:
- Journal of studies on alcohol and drugs (2026)
- Authors:
- Linden-Carmichael, Ashley N(5), Lanza, Stephanie T(3), Sokolovsky, Alexander W(4), White, Helene R, Jackson, Kristina M
- Database ID:
- RTHC-08434
Evidence Hierarchy
Frequently Asked Questions
Is using alcohol and cannabis together always dangerous?
Not equally — this study found four distinct patterns of co-use days. Only 'Heavy Use' days (14% of occasions) were significantly more harmful. The majority were 'Alcohol-Focused' or 'Cannabis-Focused' days with lower risk profiles.
What makes a co-use day more harmful?
Heavy Use days were characterized by higher quantities of both alcohol and cannabis plus engagement with other substances. Timing also mattered — Early-Day Use (starting before evening) was a distinct pattern with its own risk profile.
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Cite This Study
https://rethinkthc.com/research/RTHC-08434APA
Linden-Carmichael, Ashley N; Lanza, Stephanie T; Sokolovsky, Alexander W; White, Helene R; Jackson, Kristina M. (2026). Heterogeneity of Within-Day Simultaneous Alcohol and Cannabis Use Behaviors Among Young Adults: A Multilevel Latent Class Analysis.. Journal of studies on alcohol and drugs. https://doi.org/10.15288/jsad.25-00286
MLA
Linden-Carmichael, Ashley N, et al. "Heterogeneity of Within-Day Simultaneous Alcohol and Cannabis Use Behaviors Among Young Adults: A Multilevel Latent Class Analysis.." Journal of studies on alcohol and drugs, 2026. https://doi.org/10.15288/jsad.25-00286
RethinkTHC
RethinkTHC Research Database. "Heterogeneity of Within-Day Simultaneous Alcohol and Cannabi..." RTHC-08434. Retrieved from https://rethinkthc.com/research/linden-carmichael-2026-heterogeneity-of-withinday-simultaneous
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.