To investigate patients double diagnosed with psychosis and substance addiction (especially cannabis) treated with risperidone long-acting injectable (RLAI) for their psychosis: characteristics of treatment and psychosocial reintegration.

Adults with psychosis were changed to RLAI from their previous medication. Starting doses varied but most patients received 50 mg every two weeks. Patients were regularly followed-up by their psychiatrist from 6 months to more than 2 years after starting treatment with RLAI. A reintegration program adapted to the needs of each patient was started as early as possible with support from all available healthcare services of the department. This program focussed on family, social and professional reintegration.

Of 60 psychotic patients, 27 patients (mean age 27.7±6.1 years) had a double diagnosis of psychosis and substance addiction (especially cannabis), and were enrolled in this follow-up study. After six months, 26 out of 27 patients had no relapse of substance addiction. Patients participating in the reintegration program were able to live with their family or at home (10 patients), undertake professional education courses (7 patients), or even return to their jobs (3 patients).

Treatment with RLAI has a positive effect on patients double diagnosed with psychosis and substance addiction (especially cannabis). The association with a reintegration program adapted to the needs of each patient must be started early and maintained for as long as possible in order to have a good clinical outcome, positive impact on the addiction, improve compliance with treatment, and diminish the risk of relapse.