Long-Term Evaluation of the Effect of Quetiapine on Hallucinations, Delusions and Motor Function in Advanced Parkinson Disease

Objectives: Mental disorders (MDs) are disabling complications of Parkinson disease (PD). We set out to demonstrate the short- and long-term efficacy of quetiapine, an antipsychotic drug, in controlling hallucinations and delusions in parkinsonian patients without worsening their motor function. Since current guidelines recommend that dopaminergic drugs be decreased or even withdrawn altogether upon the appearance of MDs, we also sought to establish whether quetiapine enables a modification of this common course of action, and hence improve the management of pre-existing motor complications in affected subjects. Method: Thirty-five PD patients with disabling MDs were enrolled in this open-label study. Motor function, MDs and cognitive state were evaluated before starting quetiapine therapy and after 1, 3, and 12 months of treatment. Results: MDs significantly improved after 1, 3, and 12 months of quetiapine treatment. At the end of the study the mean daily dose of quetiapine (185 mg) did not produce significant changes in motor or cognitive function. Isolated hallucinations responded to low doses of quetiapine (110 mg daily), while delusions needed 265 mg daily. After 12 months, global dopaminergic therapy was reduced in 3 patients, modified (purely in terms of its components) in 17 patients, and increased in 15 patients. Conclusions: Quetiapine was effective in the treatment of hallucinations and delusions in PD. It did not worsen motor functions and allowed the dopaminergic treatment in PD patients affected by MDs to be managed safely.