Randomised controlled trial of the clinical and cost-effectiveness of a contingency management intervention for reduction of cannabis use and of relapse in early psychosis

Young people with early psychosis who use cannabis will be offered vouchers or small cash rewards if they can stay drug-free, in a trial testing whether this approach delays relapse. Cannabis use is common among people experiencing a first episode of psychosis, and it sharply increases the risk of relapse, hospital readmission, and long-term disability. Standard treatments—talking therapies and medication—often fail to keep these patients away from the drug. Contingency management, which provides tangible incentives for verified abstinence, has worked for other addictions but has not been rigorously tested in this group. If the trial shows that the incentive scheme extends the time between relapses, it would give mental health services a practical, low-cost tool to improve outcomes for a notoriously hard-to-treat population. The researchers will also calculate whether the intervention saves the NHS money by reducing hospital stays and crisis care. If cost-effective, the approach could be rolled out across early intervention services in the UK, changing how clinicians address cannabis use in young people with psychosis.