Clozapine for Cannabis Use in Schizophrenia

Many individuals with schizophrenia also suffer from marijuana addiction that worsens their problems related to schizophrenia. Most of the medications prescribed for schizophrenia have no effect on reducing marijuana use. Preliminary data suggests that clozapine, an atypical antipsychotic, may limit marijuana use in people diagnosed with schizophrenia, but it is not commonly used due to its side effects and is reserved for people who do not respond to other antipsychotic medications. In the proposed study, 132 individuals who are diagnosed with both schizophrenia and a cannabis use disorder will be randomized to a 12-week treatment course with either clozapine or risperidone (another commonly prescribed antipsychotic medication) to test the hypothesis that patient treated with clozapine will have decreased cannabis use as compared to patients treated with risperidone. Should this study indicate that clozapine will lessen marijuana use in persons diagnosed with schizophrenia more than risperidone, it will provide evidence needed to begin to shift clinical practice toward its use in this population.