We included 25 RCTs and found no compelling evidence to support any one psychosocial treatment over another to reduce substance use (or improve mental state) by people with serious mental illnesses. Furthermore, methodological difficulties exist which hinder pooling and interpreting results; high drop out rates, varying fidelity of interventions, varying outcome measures, settings and samples and comparison groups may have received higher levels of treatment than standard care. Further studies are required which address these concerns and improve the evidence in this important area.
Randomized controlled trial of a cannabis-focused intervention for young people with first-episode psychosis.
To evaluate a cannabis-focused intervention (cannabis and psychosis therapy: CAP) for patients continuing to use cannabis following initial treatment for first-episode psychosis (FEP).
                Consecutive admissions to an early psychosis program were screened and consenting individuals using cannabis in the 4 weeks prior to assessment participated. A single-blind randomized controlled trial compared CAP (n = 23) with a clinical control condition (psychoeducation, PE; n = 24). There were no significant differences between the CAP and PE groups on cannabis use at end of treatment and 6 months post-intervention.
                There were no significant group differences on psychopathology and functional ratings at follow-up. A significant reduction in cannabis use was observed for both groups over time.
                PE and specific cannabis-focused intervention are associated with similar reductions in cannabis use in an FEP cohort. Simple interventions may therefore be worth considering prior to intensive psychotherapeutic efforts with this population.