Intervention for cannabis use in young people at ultra high risk for psychosis and in early psychosis

Background: The aims of this service evaluation were to determine if an early intervention for cannabis use is feasible and effective in reducing cannabis use and improving functional outcomes among young people at ultra high risk (UHR) for psychosis or with early psychosis. Method: This was a naturalistic evaluation that included 58 people attending a clinical service for young people at UHR for psychosis or in the early stages of a psychotic disorder. Young people were offered a tiered intervention consisting of motivational interviewing (MI) and cognitive behaviour therapy (CBT) for cannabis use according to the severity of their use. Non-users were provided with brief advice; infrequent cannabis users were offered a four-session brief intervention and regular users were offered an eight-session intervention. Cannabis use was assessed using the Drug Use Scale of the Opiate Treatment Index (OTI) and functioning was assessed using the Global Assessment of Functioning (GAF) at initial assessment and 12 months follow-up. Results: Intervention for cannabis use was associated with a significant reduction in the average number of cannabis use occasions per day at follow-up. Only one non-cannabis user had commenced using at follow up after brief advice. Baseline cannabis users had lower GAF scores at 12-months in comparison to non-users. Conclusion: A tiered intervention for cannabis use appears to be feasible and effective for reducing cannabis use among UHR and early psychosis groups, and it is recommended to be tested in a randomised controlled trial.