Recreational cannabis access via pharmacies: A 1-year Swiss study on cannabis use and mental health.

Pichler E.; Mosandl C.; Kronschnabel J.; Meyer M.; Guessoum A.; Herrmann O.; Curiger J.; Vogel M.; Walter M.; Baltes-Flückiger L. · Drug and alcohol dependence · 2026

**Background & Methods** This Swiss prospective cohort study followed 374 regular cannabis users (mean age 35.8; 81% male) over 1 year who accessed cannabis through pharmacy-based regulated dispensing. Participants were assessed at baseline and 12-month follow-up using linear mixed-effects models to evaluate changes in depressive symptoms (PHQ-9), anxiety, problematic cannabis use (CUDIT-R), and consumption patterns under controlled conditions (pharmacist-dispensed, maximum 20% THC, ≤10g THC/month). **Key Findings** - Depressive symptoms, anxiety, and problematic cannabis use all decreased significantly but with small effect sizes (PHQ-9: 5.37 to 4.53; p<.0001 for depression, p=.0008 for anxiety, p=.0002 for CUDIT-R). However, the proportion of participants exceeding clinical diagnostic thresholds for cannabis use disorder remained statistically unchanged (32.7% to 28.6%, p=.126). - Cannabis-use frequency increased modestly (p=.0042) while total quantity consumed remained stable, suggesting users accessed the regulated supply more often but did not increase overall consumption. - High-risk users at baseline (CUDIT-R ≥13) demonstrated significantly greater reductions in problematic use scores compared to lower-risk users (group-by-time interaction, p<.0001), indicating differential benefit by baseline risk profile. **Dosage & Administration** Pharmacy-dispensed cannabis with maximum THC concentration of 20%, limited to ≤10g THC per month per user. **Safety & Adverse Effects** Not reported. **Evidence Quality** This study has significant limitations that preclude causal inference. The uncontrolled design lacks a comparison group, preventing determination of whether observed improvements resulted from regulated access, natural remission, or selection bias among treatment-seeking users. The between-person differences explained most variance (conditional R²=.57-.70) while time explained nearly none (marginal R²<.01), suggesting baseline characteristics rather than the intervention drove outcomes. The study population was predominantly male (81%) and relatively older (mean 35.8 years), limiting generalizability. While findings suggest regulated pharmacy access was not associated with mental health deterioration, the evidence level is observational (IV) and cannot establish causation or optimal policy implications without randomized controlled comparison.

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