On the Optimal Diagnosis and the Evolving Role of Pimavanserin in Parkinson’s Disease Psychosis

Parkinson's disease (PD) is associated with the development of psychosis (PDP), including hallucinations and delusions, in more than half of the patient population. Optimal PD management must therefore involve considerations about both motor and non-motor symptoms. Often, clinicians fail to diagnosis psychosis in patients with PD and, when it is recognized, treat it suboptimally, despite the availability of multiple interventions. In this paper, we provide a summary of the current guidelines and clinical evidence for treating PDP with antipsychotics. We also provide recommendations for diagnosis and follow-up. Finally, an updated treatment algorithm for PDP that incorporates the use of pimavanserin, the only US FDA-approved drug for the treatment of PDP, was developed by extrapolating from a limited evidence base to bridge to clinical practice using expert opinion and experience. Because pimavanserin is only approved for the treatment of PDP in the US, in other parts of the world other recommendations and algorithms must be considered.