EPV050
Post-Legalization Surge and Regional Disparities in Cannabis-Induced Psychiatric Disorders: Multicenter Evidence from Thailand (2021–2024)
S. Joowong 1,*, P. Tansupasiri 2
1Department of Mental Health, Somdet Chaopraya Institute of Psychiatry, Bangkok, 2Department of Mental Health, Phisanulok Psychiatric Hospital, Phisanulok, Thailand
Introduction: Following Thailand’s cannabis decriminalization in 2022, a marked rise in psychiatric presentations related to cannabis use has been observed nationwide. While international evidence has linked high-THC cannabis exposure to psychosis and substance-induced disorders, empirical data from Asian settings remain limited. This late-breaking study provides updated national trends and regional variations in cannabis-related psychiatric cases following the policy change.
Objectives:
1. To analyze the trend of cannabis-related psychiatric cases in Thailand during the period between pre-policy (2021) and after legalization (2023 and 2024).
2. To examine the association between psychiatric diagnostic codes (F1x.5 and F2x.xx) and cannabis-use history.
Methods: A retrospective multicenter study analyzed data from five psychiatric hospitals representing five major regions of Thailand (North, Northeast, Central, South, and East) between 2021 (pre-policy) and 2024 (post-policy). Demographic and clinical data were extracted from hospital records. Statistical analyses included descriptive statistics, Chi-square tests, and linear regression to assess time trends and gender–diagnosis associations between cannabis- induce psychotic disorders (F1x.5) and schizophrenic spectrum disorders (F2x.xx).
Results: Between 2021–2024, 2,131 cannabis-related psychiatric patients were identified (82.4% male, 17.6% female). Cases increased significantly post-legalization, with an average annual rise of 146.6 cases (β = +146.6, R² = 0.875). Males were more likely to be diagnosed with F1x.5, while females showed higher proportions of F2x.xx (χ² = 122.5, p < 0.001). The proportion of patients with cannabis-use history among F1x.5 diagnoses rose from 62.4% (2021) to 78.3% (2024), indicating a significant upward trend (χ²trend = 8.52, p = 0.004),while among F2x.xx patients, it increased from 18.7% to 27.5% during the same period. Regional analysis revealed higher cannabis-related prevalence in northeastern hospitals (up to 48.3%), whereas southern and northern hospitals showed stronger psychotic disorder patterns.
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Conclusions: This study provides one of the first multicenter evidences from Thailand demonstrating a post-legalization rise in cannabis-induced psychiatric morbidity. The results call for innovative, regionally tailored, and gender-sensitive strategies within national mental health surveillance systems.
Disclosure of Interest: None Declared