The effect of quetiapine in psychotic Parkinsonian patients with and without dementia: An open-labeled study utilizing a structured interview

Objectives: We studied the effect of quetiapine in drug-induced psychosis (DIP) in Parkinson's disease (PD) patients with dementia (PDDEM) and without dementia (PDNODEM) in a 6-month open study. Methods: Thirty-five consecutive PD patients with DIP (19 of them demented [DSMIV criteria]) were examined. Assessment included Mini-Mental State Examination (MMSE), UPDRS (motor part), Brief Psychiatric Rating Scale (BPRS), Clinical Global Improvement Scale (CGIS) and Hamilton test (for depression). Quetiapine was administered in a flexible dose 25-600 mg daily. Out of the 35 patients included in the study, 24 completed treatment with quetiapine (14 demented and 10 without dementia). Treatment was stopped in 11 patients (5 demented). Results: Intention to treat patient (ITT) analysis did not show a significant quetiapine effect (BPRS), although in about 30 % a good outcome was reported by the family (CGIS). Among the patients who completed the study (n = 24), in the PDNODEM group (n = 10) BPRS improved almost significantly (p = 0.06) while in the PDDEM group the BPRS did not change. According to the CGIS, a good improvement was observed in 50% of the PDDEM group (7/14) and 40% of the PDNODEM group (4/10). Motor features of PD patients worsened mildly (p = 0.05) in the PDDEM group. Conclusions: In this open trial, quetiapine was not beneficial in the ITT group using the BPRS, although families reported improvement in about 30% of patients (CGIS). Among patients who completed the study, quetiapine was more effective in the PDNODEM group. A double blind study with quetiapine is required.