Within 2-4 years of recreational dispensaries opening, cannabis use prevalence increased 11% among teens, 17% among young adults, and 33% among adults over 26 across five early-legalizing states.
Policymakers evaluating legalization impacts, public health researchers, and anyone interested in how legal cannabis markets change use patterns.
82% increase in cannabis initiation among adults over 26
What the researchers found
Using the synthetic control method, recreational cannabis markets were associated with moderate increases in adolescent use prevalence and initiation (11% and 13%), large increases among young adults 18-25 (17% and 33%), and the largest increases among adults 26+ (33% prevalence increase, 82% initiation increase) within 2-4 years of dispensary opening.
Why it matters
This study uses one of the strongest causal inference methods available for policy evaluation. The finding that older adults showed the largest increases challenges the focus on youth in cannabis policy debates and suggests that recreational markets are primarily expanding use among populations that were not previously using.
The numbers in context
Ages 12-17: +11% prevalence, +13% initiation. Ages 18-25: +17% prevalence, +33% initiation. Ages 26+: +33% prevalence, +82% initiation. Effects measured 2-4 years post-dispensary opening across 5 states.
How the study worked
Synthetic control method with staggered treatment adoption applied to state-level data from the National Survey on Drug Use and Health. Five states analyzed: Colorado, Washington, Oregon, Alaska, and Nevada. Synthetic controls were constructed from non-legalizing states matched on pre-treatment demographics and cannabis use trends. Jackknife confidence intervals were used.
What this study cannot tell us
Only five early-legalizing states were included; later states may show different patterns. The NSDUH data relies on self-report and may undercount use. The 2-4 year follow-up window may not capture longer-term trends. Synthetic controls cannot account for all possible confounders.
How to read the evidence
Strong causal inference method (synthetic control) applied to nationally representative survey data across 5 states. Among the most rigorous designs available for policy evaluation.
When this study was published
Published in 2025 with NSDUH data from 2013-2019.
The bigger picture
The 82% increase in initiation among adults 26+ is striking and suggests that legal retail access is creating a large new population of cannabis users who would not have otherwise tried the drug. Whether this translates to increased health harms or relatively benign experimentation remains to be determined.
Questions still open
- Will the increases in use plateau as novelty wears off? Are the new older adult users developing patterns of problematic use, or is most of the increase in occasional use?
Common questions
What is the synthetic control method?
Did teen use increase significantly?
Read the original research
The Impact of Recreational Cannabis Markets on Cannabis Use Among Adolescents and Adults: A Synthetic Control Analysis.
Cannabis (Albuquerque, N.M.), 8(1), 50-64
Citation
Marinello, Samantha. (2025). The Impact of Recreational Cannabis Markets on Cannabis Use Among Adolescents and Adults: A Synthetic Control Analysis.. Cannabis (Albuquerque, N.M.), 8(1), 50-64. https://doi.org/10.26828/cannabis/2024/000224