International cannabis policies and their association with cannabis use, cannabis use disorder, and other psychiatric disorders.
Table of Contents
Clinical Takeaway
Legalizing cannabis for non-medical use in places like Canada and the United States has been linked to more adults using cannabis, higher rates of cannabis use disorder, and increased product potency. The research does not show a consistent connection between policy changes and broader psychiatric disorder rates. These findings suggest that commercialized legal markets expand access and use among adults, with measurable clinical consequences worth monitoring.
#32 International cannabis policies and their association with cannabis use, cannabis use disorder, and other psychiatric disorders.
Citation: Freeman Tom P et al.. International cannabis policies and their association with cannabis use, cannabis use disorder, and other psychiatric disorders.. The lancet. Psychiatry. 2026. PMID: 42309107.
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Abstract: Cannabis policies vary from strict prohibition to commercialised legalisation and are rapidly evolving worldwide. Here, we reviewed evidence for associations between international cannabis policy changes from 2000-25 and cannabis use, cannabis use disorder, and other psychiatric disorders. Commercialised legal markets for non-medical use in Canada and the USA were associated with increased prevalence of cannabis use and cannabis use disorder in adults and increases in cannabis potency since legalisation. There was no consistent evidence for associations between policy change and the prevalence or incidence of psychotic disorders. Commercialised legalisation was associated with an increase in hospital admissions for psychosis, and for psychotic disorders comorbid with cannabis use disorder. Poorly regulated legal access to medical cannabis, in the absence of efficacy and safety data, could increase risk of harm. Policies that limit commercialisation, such as strictly regulated legalisation of medical or non-medical supply, were not as strongly associated with cannabis use or psychiatric disorders, but long-term evaluation is needed. There was little evidence that decriminalisation of non-medical cannabis in Europe, Africa, Oceania, and Asia was associated with cannabis use or psychiatric disorders.
What This Study Teaches Us
Commercialized legal cannabis markets in North America have been associated with increased use, cannabis use disorder, and hospital admissions for psychosis, but decriminalization without commercialization in Europe and other regions has not shown these same associations. Strict regulation of medical or non-medical supply appears to carry less psychiatric risk than fully commercialized markets.
Why This Matters Clinically
Clinicians need to know that cannabis policy itself is a risk factor worth discussing with patients, and that the type of legalization matters. Whether a patient lives in a commercialized market versus a medically-regulated one changes the baseline risk profile for both addiction and acute psychiatric emergencies they may encounter.
Study Snapshot
| Study Design | Narrative review of evidence on cannabis policy changes and associated outcomes from 2000-2025 |
| Population | International populations across jurisdictions with varying cannabis policies; no single cohort described |
| Intervention | Cannabis policy changes categorized as prohibition, decriminalization, regulated medical legalization, or commercialized legalization |
| Primary Outcome | Associations between policy type and prevalence of cannabis use, cannabis use disorder, psychotic disorders, and hospital admissions |
| Key Result | Commercialized legalization associated with increased use disorder and psychosis hospital admissions; decriminalization not associated with increased psychiatric burden; regulated medical access had intermediate risk |
Where This Paper Deserves Skepticism
This is a narrative review, not a meta-analysis, so quality assessment and publication bias are not addressed. The abstract does not specify how many studies were included, whether confounders like changing demographics or other drug policies were adjusted for, or how long-term outcomes were measured. The causal directionality remains unclear: did legalization increase use and disorder, or did higher baseline use drive legalization? Different countries’ data collection methods and definitions of cannabis use disorder may not be comparable.
Dr. Caplan’s Take
This review helps clarify that not all legalization is equal from a public health standpoint. The distinction between commercialized markets (which actively promote sales) and tightly regulated medical or non-medical programs is important clinically. I’m cautious about the psychosis findings because the abstract notes no consistent evidence for policy changes affecting psychotic disorder incidence itself, only hospital admissions, which could reflect detection bias or care-seeking patterns rather than true disease burden. Still, the data on increased use and use disorder in commercialized markets is consistent enough to warrant honest conversations with patients about market forces they’re exposed to.
Clinical Bottom Line
When counseling patients about cannabis use, the regulatory environment they live in is part of the risk calculation. Commercialized legalization carries higher risks for use disorder and acute psychiatric care; tight medical regulation or decriminalization-without-commercialization appears safer, though long-term evidence is still limited.
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