Effects of quetiapine at low doses on psychosis motor disability and stress of the caregiver inpatients with Parkinson's disease

Introduction. Quetiapine is a novel neuroleptic drug with pharmacological properties close to clozapine, the most effective drug in the management of psychotic symptoms inpatients with Parkinson's disease (PD). Unlike clozapine, however, quetiapine does not induce agranulocytosis and therefore no haematologic controls are required. Objectives. To assess tolerability and effectiveness of low-dose quetiapine on psychotic symptoms, sleep disturbances and stress of the caregiver in PD patients with dopaminomimetic psychosis. Patients and methods. We carried out a 16-week, prospective, open-label study on the effects of quetiapine in 7 consecutive PD patients with psychosis. A ceiling dose was arbitrarily established at 25 mg/d. Antiparkinsonian medication remained unchanged throughout the study. Motor symptoms were assessed with UPDRS motor subscale portion, Schwab-England scale, and Hoehn-Yahr diseases staging. The effects on hallucinations and paranoia, sleep disorder, and stress in the caregiver were scored separately, aside from a global score on the Neuropsychiatric Inventory (NPI). Global impression of both, investigators and caregiver was obtained at study conclusion. A patient died from unrelated causes. Results. Under a mean quetiapine dose of 24.9 mg/d (12.5-37.2) motor impairment during 'on' periods-remained unchanged, both according to patients and caregiver whereas mean UPDRS motor score remained unchanged (35.5 +/- 4.5 versus 32.8 +/- 5.2). Levodopa-induced dyskinesias disappeared in the single patient with this complication. Improvement occurred in mean NPI global score, as well as subscores for hallucinations and paranoia, and caregiver stress. In over half the patients, effectiveness was scored as very good or good both by examiners and caregivers. A confusional episode occurred in one patient under 25 mg/d but readily resolved while maintaining the benefit following dose reduction to 12.5 mg. Conclusion. Quetiapine at low doses appears a useful alternative for psychotic symptoms, sleep disorders and stress of the caregiver in patients with PD.