Early psychosis care cuts cannabis use by two-thirds in young people

Early intervention in psychosis (EIP) services aim to prevent transition to psychosis and improve outcomes for at-risk young people. Substance use is a modifiable risk factor that substantially influences functioning yet remains understudied in this population. The authors aimed to establish substance use rates at treatment initiation, examine substance use trajectories during the first 6 months of EIP care, and explore differences in these trajectories within age, gender, and clinical severity subgroups within a cohort of young people in Australia at risk for psychosis. Participants were ages 12-25 years, met criteria for psychosis risk, and accessed the national headspace Early Psychosis program. Past-3-month substance use was assessed at baseline and at 90-day intervals. Mixed-effects logistic regression was used to examine changes over time, across the whole cohort and within subgroups, in analyses controlled for demographic and clinical factors. Among 1,966 participants, substance use at treatment entry was common, with participants reporting past-3-month use of alcohol (60%), cannabis (43%), tobacco (41%), sedatives (15%), and amphetamine-type stimulants (ATS, 15%). Across 6 months of treatment, the odds of reported use during the past 3 months significantly decreased for cannabis (OR=0.32), ATS (OR=0.39), sedatives (OR=0.42), and alcohol (OR=0.71), with a nonsignificant decrease in tobacco use. Reductions in substance use were greater among those ages ≥18 at treatment onset. EIP services were associated with reductions in illicit substance use but had limited impact on tobacco use. Targeted strategies to address persistent use of these substances should be integrated into routine EIP care.