Among over 15,000 young adults in Washington state, cannabis use increased from ages 18-22 and plateaued through 26, with social norms and low perceived harm most consistently driving use.
Prevention professionals targeting young adults and policymakers evaluating post-legalization use trends.
Use peaked at age 22 and plateaued through age 26
What the researchers found
Cannabis use prevalence increased from ages 18-22 and remained relatively stable through age 26. Ease of access, social norms, and low perceived harm were associated with use, but the strength of these associations varied by age. Injunctive norms (perceptions of use acceptability) and low perceived psychological harm were the most consistent predictors across the full age range.
Why it matters
Understanding which risk factors matter most at different ages can help target prevention efforts. The finding that perceived acceptability drives use well into the mid-20s, and that perceived psychological harm becomes more influential with age, suggests that prevention messaging should evolve as young adults mature.
The numbers in context
N = 15,251. Mean age 22.02. 68% female. Use increased ages 18-22, stable through 26. Injunctive norms rose substantially through age 23, then decreased. Ease of access and descriptive norms had strongest associations around age 18. Low perceived physical harm associations got somewhat stronger with age.
How the study worked
Repeated cross-sectional data from 15,251 young adults (mean age 22, 68% female) in the Washington Young Adult Health Survey from 2015-2022 (post-legalization). Logistic time-varying effect models examined age-varying associations between risk factors and cannabis use (any and frequent past-month use).
What this study cannot tell us
Repeated cross-sectional design means different individuals were surveyed at different ages, not the same people tracked over time. Washington-specific findings may not apply to states with different legal frameworks. Self-report measures may undercount actual use.
How to read the evidence
Large statewide survey with over 15,000 respondents and sophisticated age-varying models. Strong cross-sectional evidence, though not longitudinal.
When this study was published
Published in 2025 with data from 2015-2022.
The bigger picture
Washington was among the first states to legalize recreational cannabis. This study captures how use patterns develop in a fully legal environment, showing that even with easy access, use peaks in the early 20s and does not continue climbing through the mid-20s.
Questions still open
- Would the age plateau pattern differ in states where cannabis remains illegal? Can targeted messaging about psychological harms effectively reduce use in mid-20s adults?
Common questions
Does cannabis use keep increasing after the early 20s?
What matters more for preventing use: access or attitudes?
Read the original research
Age-Varying Patterns of Cannabis Use, Related Risk Factors, and their Associations among Young Adults in the Context of Legalized Nonmedical Cannabis.
Prevention science : the official journal of the Society for Prevention Research, 26(5), 773-784
Citation
Martinez, Griselda; Calhoun, Brian H; Fleming, Charles B; Linden-Carmichael, Ashley N; Acolin, Jessica; Rhew, Isaac C; Kilmer, Jason R; Larimer, Mary E; Guttmannova, Katarina. (2025). Age-Varying Patterns of Cannabis Use, Related Risk Factors, and their Associations among Young Adults in the Context of Legalized Nonmedical Cannabis.. Prevention science : the official journal of the Society for Prevention Research, 26(5), 773-784. https://doi.org/10.1007/s11121-025-01803-0
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