- All HHC-related cases occurred in first episode psychosis.
- HHC-only cases had higher rates of affective symptoms (89%) than cannabis-only (54%) and combined (27%) (p = 0.024).
- Formal thought disorder was more common in HHC-exposed groups (80%) than cannabis-only (38%), significant in exploratory comparison (p = 0.027).
Ir J Psychol Med. 2026 Oct 19:1-6. doi: 10.1017/ipm.2026.10240. Online ahead of print.
ABSTRACT
OBJECTIVES: To describe the demographic, clinical, and treatment characteristics of individuals admitted with hexahydrocannabinol (HHC)-associated psychosis and compare with cannabis-associated psychosis.
METHODS: A retrospective chart review was undertaken of all admissions to the Adult Acute Mental Health Unit at University Hospital Galway, Ireland, between 1 May 2023 and 31 July 2025, with psychosis and documented HHC or cannabis use in the seven days preceding admission. Demographic, clinical, and treatment variables were compared across three groups: HHC-only, cannabis-only, and combined HHC + cannabis associated psychosis. Group differences were examined using ANOVA for continuous variables and Fisher’s exact tests for categorical variables, with repeated-measures ANOVA used to examine antipsychotic dosing. Analyses were exploratory in nature.
RESULTS: Thirty-three individuals (79% male) met inclusion criteria. All HHC-related cases occurred in a first episode of psychosis. Affective symptoms were more frequent in the HHC-only group (89%) than in the cannabis-only (54%) and combined HHC + cannabis groups (27%) (p = 0.024). Formal thought disorder appeared more common in HHC-exposed groups (80%) compared with cannabis-only presentations (38%), reaching statistical significance in an exploratory comparison between cannabis-only and combined HHC-exposed groups (p = 0.027). Urine toxicology screening for THC metabolites, length of stay and maximum antipsychotic dose were similar across groups.
CONCLUSION: In this cohort, HHC-associated psychosis was associated with higher rates of affective symptoms and formal thought disorder than cannabis-related presentations, despite otherwise similar clinical features. Findings are hypothesis-generating, given the exploratory analyses, small sample and uncorrected multiple testing. They suggest a potential role for novel cannabinoid screening to support earlier identification and management.
PMID:42894889 | DOI:10.1017/ipm.2026.10240
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