Among 835 high school students, those who purchased cannabis from someone or used a valid medical card at a dispensary had significantly higher odds of continued cannabis use six months later.
Prevention researchers, policymakers considering youth cannabis access, and clinicians authorizing medical cannabis for adolescents.
Medical card use: 2x odds of continued cannabis use
What the researchers found
Most youth (72%) received cannabis for free. 51% bought from someone, 16% used a medical card at a dispensary, and 4% grew their own. Buying from someone (OR 1.46) and using a valid medical card (OR 1.99) predicted any cannabis use six months later. Buying from someone also predicted more frequent use (RR 1.25).
Why it matters
Understanding which access points predict escalation helps target prevention. The finding that medical card access predicted the strongest continued use raises questions about youth medical cannabis authorization.
The numbers in context
835 high schoolers (mean age ~17). 72.1% received cannabis free. 50.9% bought from someone (OR 1.46 for continued use). 15.9% used valid medical card (OR 1.99). 3.9% self-grown. Buying from someone: RR 1.25 for frequency.
How the study worked
Longitudinal study of 835 high schoolers completing 3 semiannual surveys. Time-lagged repeated-measures regression examined how cannabis sources at one wave predicted use frequency six months later. Seven source types assessed as separate dichotomous variables.
What this study cannot tell us
Self-reported sources. California-based sample during specific legal period. Six-month intervals may miss shorter-term patterns. Cannot determine whether the source caused continued use or whether more committed users seek out purchasing sources.
How to read the evidence
Longitudinal design with time-lagged analysis and large adolescent sample, but self-reported and single geographic area.
When this study was published
Published in 2022.
The bigger picture
The finding that medical card dispensary access was the strongest predictor of continued use suggests that legitimate access channels may paradoxically facilitate more persistent patterns of adolescent use.
Questions still open
- Should medical cannabis authorization for minors include monitoring for escalation? Does free cannabis access (social sharing) represent a safer pattern because it is less reliably available?
Common questions
Where do teens get cannabis?
Does how teens get cannabis matter?
Read the original research
Associations of cannabis product source and subsequent cannabis use among adolescents.
Drug and alcohol dependence, 233, 109374
Citation
Kelleghan, Annemarie R; Sofis, Michael J; Budney, Alan; Ceasar, Rachel; Leventhal, Adam M. (2022). Associations of cannabis product source and subsequent cannabis use among adolescents.. Drug and alcohol dependence, 233, 109374. https://doi.org/10.1016/j.drugalcdep.2022.109374
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