Background: Alcohol and cannabis use disorders worsen the course of schizophrenia. While the typical antipsychotics are of limited value in controlling substance use in schizophrenic patients, previous studies suggest that the novel antipsychotic clozapine (CLOZ) may decrease their substance use. We describe a retrospective study of the effects of the novel antipsychotics risperidone (RISP) and clozapine on alcohol and cannabis use in patients with schizophrenia or schizoaffective disorder and comorbid alcohol and/or cannabis use disorder.
Method: This study involved retrospective assessment of abstinence (cessation of alcohol and cannabis use) in 41 patients treated with either risperidone (n=8) or clozapine (n=33) for at least 1 year. In 32 of these 41 patients, information was available on whether abstinence occurred during the 1-year period.
Results: Abstinence rates were significantly higher in patients treated with clozapine than in those treated with risperidone (54% vs. 13%, p=0.05). The nine patients treated for at least 1 year, but excluded from the analysis because time of cessation of use was not known, had all stopped alcohol/cannabis use during clozapine treatment.
Discussion: While the limitations of this retrospective study must be recognized, the data suggest that comorbid patients treated with clozapine are more likely to abstain from alcohol and cannabis use than are those treated with risperidone. Further prospective studies will be required to confirm these intriguing results.