Pharmacy Faculty Publications

Management of Hallucinations and Psychosis in Parkinson's Disease

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The American Journal of Geriatric Pharmacotherapy







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Hallucinations and psychosis are common in patients with Parkinson's disease (PD), with reported prevalences of up to 48% and 80%, respectively. However, few randomized, double-blind, placebo-controlled trials evaluating the treatment options have appeared in the literature. The studies that have been published were complicated by lack of agreement on the diagnosis of psychosis in PD, poor completion rates, mixed populations that included dementia, and other issues. Several reviews, guidelines, and consensus statements have sought to establish standards for treating these symptoms of PD. In 2006, the American Academy of Neurology (AAN) published a practice guideline (based on articles published up to 2004) for management of depression, psychosis, and dementia in patients with PD. Since then, a number of relevant studies have been published. Objective: The purpose of this article was to review data that have appeared in the literature since publication of the AAN guideline regarding the management of hallucinations and psychosis in PD. Methods: A literature search of the PubMed, CINAHL, and PsychInfo databases was conducted for human studies published in English from January 2004 to June 2010. All clinical studies were included except case reports and case series. Studies withpsychosis, hallucinosis, hallucination, delusion, Parkinson, atypical antipsychotic, neuroleptic, aripiprazole, clozapine, olanzapine, quetiapine, risperidone, and ziprasidone. Results: Thirteen studies were included in the review: 3 studies of clozapine, 7 studies of quetiapine, 2 head-to-head trials comparing quetiapine and clozapine, and 1 noncomparative trial of clozapine or quetiapine interventions. Most of the studies included participants with a mean age in the early to mid 70s and a mean duration of PD typically >10 years. Conclusions: Results of the identified studies suggested that patients with PD might benefit from long-term clozapine therapy. Results of the quetiapine studies were conflicting. However, no statistically significant difference in effectiveness was found between quetiapine and clozapine in comparative trials. The significance of the differences in treatment responses between patients with dementia and those without dementia remains unclear, and it was not possible to draw conclusions for or against other atypical antipsychotics because of insufficient evidence. Further studies are needed to address the methodologic issues in the current trials and to assess safety issues in larger cohorts.


Parkinson's disease, hallucinosis, hallucinations, psychosis, atypical antipsychotics, neuroleptics

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