Cannabis and Binge Drinking Fuel Each Other in Young Adults — But the Pattern Reverses by Age 25
In a national cohort of 18–25-year-olds, increases in cannabis use predicted subsequent increases in binge drinking between ages 18–21, but by ages 24–25, increases in cannabis use predicted decreases in binge drinking.
Quick Facts
What This Study Found
Within-person increases in cannabis use predicted subsequent increases in binge drinking between ages 18–21, but the same within-person increases in cannabis use predicted decreases in binge drinking between ages 24–25. Binge drinking did not predict subsequent changes in cannabis use at any age.
Key Numbers
N = 526 from the NCANDA cohort, ages 18–25. Cannabis use predicted increased binge drinking ages 18–21 but decreased binge drinking ages 24–25. Binge drinking did not predict subsequent cannabis use changes at any age.
How They Did This
Parallel-process state-trait mixed effect growth models using NCANDA cohort data from 526 participants aged 18–25 reporting alcohol and cannabis use. Models tested reciprocal within-person associations and age-varying effects across emerging adulthood.
Why This Research Matters
This study reveals that the relationship between cannabis and binge drinking changes direction with age. In younger adults, cannabis may enable heavier drinking, but in mid-20s adults, cannabis may actually substitute for alcohol — with important implications for dual-use interventions.
The Bigger Picture
The age-dependent reversal is crucial: interventions targeting cannabis use in college-age adults (18–21) might also reduce binge drinking, while the substitution effect emerging by age 24–25 suggests cannabis and alcohol may serve increasingly different roles as adults mature.
What This Study Doesn't Tell Us
Observational longitudinal data cannot prove causation. NCANDA is a neurodevelopment-focused cohort that may not represent all emerging adults. Self-reported substance use. The transition point between 21 and 24 is not well-characterized.
Questions This Raises
- ?What drives the reversal — maturation, changing social contexts, or legal drinking age effects?
- ?Would reducing cannabis use in 18–21-year-olds actually reduce their binge drinking?
- ?Does the substitution effect at 24–25 reflect healthier choices or just different substances?
Trust & Context
- Key Stat:
- Evidence Grade:
- Longitudinal national cohort with sophisticated within-person modeling, providing strong evidence for temporal sequencing though not causation.
- Study Age:
- Published 2025.
- Original Title:
- Mutual age-varying influences of binge drinking and cannabis use during emerging adulthood in the NCANDA cohort.
- Published In:
- Alcohol, clinical & experimental research, 49(10), 2239-2249 (2025)
- Authors:
- Waddell, Jack T(3), Brumback, Ty, Baker, Fiona C(6), Cheek, Shayna, Clark, Duncan B, Goldston, David B, Grove, Jeremy L, Nagel, Bonnie J, Nooner, Kate B, Pfefferbaum, Adolf, Pohl, Kilian M, Sullivan, Edith V, Tapert, Susan F, Thompson, Wesley K, Brown, Sandra A
- Database ID:
- RTHC-07888
Evidence Hierarchy
Frequently Asked Questions
Does cannabis make young people drink more?
Between ages 18–21, increases in cannabis use did predict subsequent increases in binge drinking. But by ages 24–25, the opposite was true — more cannabis use predicted less binge drinking. The relationship depends heavily on age.
Does binge drinking lead to more cannabis use?
No — in this study, binge drinking did not predict subsequent changes in cannabis use at any age. The predictive relationship was one-directional, from cannabis to alcohol.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-07888APA
Waddell, Jack T; Brumback, Ty; Baker, Fiona C; Cheek, Shayna; Clark, Duncan B; Goldston, David B; Grove, Jeremy L; Nagel, Bonnie J; Nooner, Kate B; Pfefferbaum, Adolf; Pohl, Kilian M; Sullivan, Edith V; Tapert, Susan F; Thompson, Wesley K; Brown, Sandra A. (2025). Mutual age-varying influences of binge drinking and cannabis use during emerging adulthood in the NCANDA cohort.. Alcohol, clinical & experimental research, 49(10), 2239-2249. https://doi.org/10.1111/acer.70139
MLA
Waddell, Jack T, et al. "Mutual age-varying influences of binge drinking and cannabis use during emerging adulthood in the NCANDA cohort.." Alcohol, 2025. https://doi.org/10.1111/acer.70139
RethinkTHC
RethinkTHC Research Database. "Mutual age-varying influences of binge drinking and cannabis..." RTHC-07888. Retrieved from https://rethinkthc.com/research/waddell-2025-mutual-agevarying-influences-of
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.