Objective: To report the results of the 12-week, prospective, open label extension of the 4-week, multicenter, placebo-controlled, double-blind PSYCLOPS (PSYchosis and CLOzapine in the treatment of Parkinsonism) trial. This extension examined the chronic safety and efficacy of clozapine in the treatment of drug-induced psychosis in Parkinson's disease (PD).
Background: Psychosis is a serious late complication of PD and may be a harbinger to increased mortality. Clozapine, the first atypical antipsychotic, was shown in several small open label studies to improve psychosis without worsening of motor symptoms. This was recently confirmed in the double-blind PSYCLOPS trial.
Methods: The 53 patients who completed the double-blind portion of PSYCLOPS were evaluated on their original randomized treatment (clozapine or placebo), then had study medication stopped. All were started on clozapine. The patients from both treatment groups were evaluated every 4 weeks over a 12-week period using standardized measures for psychosis and PD.
Results: The mean dose of clozapine was 28.78 mg/day. Those originally treated with placebo improved significantly in Brief Psychiatric Rating Scale and clinical global scores for psychosis to the same degree as the group originally randomized to clozapine in the double-blind study. Both groups maintained their response to week 16 (end of the combined double-blind and open label portions). There was no worsening of motor features as measured by the Unified Parkinson's disease rating scale. Eighteen patients were either hospitalized or died during the trial. The most common reasons were pulmonary.
Conclusions: Low-dose clozapine is effective in treating drug-induced psychosis without worsening motor features of PD, and the response is maintained for at least 4 months. Patients with psychosis and PD were previously described as a group with high risk for morbidity and mortality. The high risk continues despite antipsychotic therapy.