Olanzapine treatment for dopaminergic-induced hallucinations

Atypical antipsychotic medications with lower affinities for D2 receptors are considered useful alternatives to treat drug-induced hallucinations in Parkinson's disease (PD). We conducted a double-blind, placebo-controlled, unforced titration, parallel design study (2:1 drug to placebo randomization ratio) using olanzapine (2.5-10 mg/day to effect) in 30 PD patients with drug-induced hallucinations. We performed an extensive battery of neuropsychological tests, the Unified Parkinson's Disease Rating Scale (UPDRS), assessments of on and off time at baseline and at 9 weeks after starting the medication. Sixteen patients on olanzapine (mean dose, 4.6 mg/night) and 11 on placebo completed the study. Compared with placebo, performance on the UPDRS item 2 (thought disorder), and a structured interview for hallucinations, both tended to improve on drug but neither reached statistical significance. A neuropsychological test battery did not show any significant differences. Total on UPDRS motor scores (P < 0.05) and timed tapping (P < 0.01) worsened while on drug compared to placebo. Bradykinesia (P < 0.01) and gait (P < 0.001) items on the UPDRS largely accounted for this deterioration. After completion of the study, 8 of 16 patients randomly assigned to drug continued olanzapine at a mean dose of 2.4 mg/day. However, at the last recorded visit only 5 of 24 (20.8%) of all patients exposed to drug (including those originally randomly assigned to placebo) remained on olanzapine. In patients with PD, low-dose olanzapine did not significantly improve hallucinations but did worsen motor function.