Young adult cannabis use increased more in states with full legalization than medical-only states
Cannabis and blunt use among young adults increased in all 16 studied states between 2002-2018, but increases were larger in states with adult-use laws compared to medical-only states, particularly after retail outlets opened.
Quick Facts
What This Study Found
All states showed declining cigarette smoking, slight cigar declines, and increasing cannabis and blunt use among young adults. Cannabis use increased following opening of medical retail outlets and further after adult-use implementation. In Maine, cannabis use increased 22.4% after medical retail opened and continued rising after adult use was adopted.
Key Numbers
16 states studied (2002-2018). Maine: 22.4% increase in cannabis use (95% CI: 19.0-29.4) after medical retail opened. All states showed declining cigarette use. Cannabis and blunt use increased more in AMU vs MUO states.
How They Did This
Segmented regression analysis of National Survey on Drug Use and Health data (2002-2018) in 16 states that passed adult and medical use or medical-only cannabis laws. Past 30-day cannabis, blunt, cigarette, and cigar use examined.
Why This Research Matters
This provides evidence that cannabis legalization, particularly the opening of retail outlets rather than just passing laws, is associated with increased young adult use. The simultaneous decline in cigarette smoking suggests shifting substance preferences rather than simply adding a new substance.
The Bigger Picture
The finding that retail outlet opening, not law passage, appears to drive use increases has important implications for states considering legalization. Implementation details (when and how products become available) may matter more than the legal change itself.
What This Study Doesn't Tell Us
Ecological study cannot prove individual-level causation. State-level trends are confounded by many other policy, economic, and cultural changes occurring simultaneously. NSDUH data may undercount some populations.
Questions This Raises
- ?Does the increase in cannabis use among young adults translate to increased harm?
- ?Could delayed retail outlet opening after legalization reduce the initial surge in use?
Trust & Context
- Key Stat:
- increase in young adult cannabis use in Maine after medical cannabis retail outlets opened
- Evidence Grade:
- National survey data with appropriate segmented regression, but ecological design and multiple confounding state-level factors limit causal claims.
- Study Age:
- 2025 publication analyzing 2002-2018 data.
- Original Title:
- Temporal Trends in Young Adult Cannabis and Tobacco Use in States with Different Cannabis Policies.
- Published In:
- Cannabis (Albuquerque, N.M.), 8(2), 98-111 (2025)
- Authors:
- Glasser, Allison M(3), Uriarte, Caitlin, King Jensen, Jessica, Sterling, Kymberle, Shang, Ce, Hammond, David, Villanti, Andrea C
- Database ID:
- RTHC-06548
Evidence Hierarchy
Watches what happens naturally without intervening.
What do these levels mean? →Frequently Asked Questions
Does legalization cause more young adults to use cannabis?
This study shows an association between legalization (especially retail sales) and increased use, but cannot prove causation. Many other factors changed simultaneously in these states. The increases were modest and cigarette use declined.
Why does retail opening matter more than the law itself?
Laws create legal permission, but retail outlets create physical access. When cannabis becomes as easy to purchase as alcohol, use appears to increase. States that passed laws but delayed retail implementation saw use increases primarily after stores opened.
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Cite This Study
https://rethinkthc.com/research/RTHC-06548APA
Glasser, Allison M; Uriarte, Caitlin; King Jensen, Jessica; Sterling, Kymberle; Shang, Ce; Hammond, David; Villanti, Andrea C. (2025). Temporal Trends in Young Adult Cannabis and Tobacco Use in States with Different Cannabis Policies.. Cannabis (Albuquerque, N.M.), 8(2), 98-111. https://doi.org/10.26828/cannabis/2025/000288
MLA
Glasser, Allison M, et al. "Temporal Trends in Young Adult Cannabis and Tobacco Use in States with Different Cannabis Policies.." Cannabis (Albuquerque, 2025. https://doi.org/10.26828/cannabis/2025/000288
RethinkTHC
RethinkTHC Research Database. "Temporal Trends in Young Adult Cannabis and Tobacco Use in S..." RTHC-06548. Retrieved from https://rethinkthc.com/research/glasser-2025-temporal-trends-in-young
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.