Long-term follow-up (24 months) of quetiapine treatment in drug-induced Parkinson disease psychosis.

OBJECTIVES: To evaluate the long-term outcome of quetiapine (QTP) use for drug-induced psychosis in Parkinson disease as assessed by the primary caregiver using the Clinical Global Impression Scale. METHODS: Thirty-five patients (mean age+/-SD, 76.1+/-5.9 years; mean disease duration+/-SD, 10.3+/-5.3 years; 19 with dementia) were followed up over a 24-month period. RESULTS: At 6 months, 20 (57%) responded to QTP, of whom 11 (31%) maintained their improvement in the long term (for 24 months). Altogether, 15 patients (43%) responded to QTP in the long term (11 were still on treatment at 24 months, 3 stopped because of improvement and medication was no longer required, and 3 stopped because of financial reasons [one was responding positively by the time of stopping medication]). The medications of nonresponding patients (n=15) were switched to clozapine, with a positive response in 12 patients (80%). CONCLUSIONS: In long-term follow-up, 31% of parkinsonian patients with psychosis treated with QTP were still on QTP therapy at 24 months. For those failing to respond to QTP, clozapine was an effective alternative therapy.