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.
College health professionals, substance use researchers, and clinicians working with young adults on dual-use patterns.
What the researchers 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.
Why it 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 numbers in context
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 the study worked
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.
What this study cannot 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.
How to read the evidence
Longitudinal national cohort with sophisticated within-person modeling, providing strong evidence for temporal sequencing though not causation.
When this study was published
Published 2025.
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.
Questions still open
- 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?
Common questions
Does cannabis make young people drink more?
Does binge drinking lead to more cannabis use?
Read the original research
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
Citation
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
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