Treatment of Parkinson's Disease-Related Psychosis

To provide an updated, clinically oriented overview of therapeutic strategies for Parkinson's disease-related psychosis (PDP), integrating current evidence on risk factors and available pharmacological and non-pharmacological treatments.

This is a narrative, non-systematic review summarizing findings from targeted searches of PubMed, Embase, and Scopus, focusing on clinical trials, observational studies, consensus guidelines, and high-quality reviews addressing the epidemiology, pathophysiology, and management of PDP. Evidence was analyzed qualitatively, with emphasis on consistency of findings, clinical applicability, and areas of ongoing uncertainty.

PDP affects a substantial proportion of individuals with Parkinson's disease and is associated with cognitive decline, increased caregiver burden, higher rates of institutionalization, and elevated mortality. Management begins with the identification of reversible triggers, environmental optimization, and rational adjustment of antiparkinsonian medications. When antipsychotic therapy is required, pimavanserin and clozapine demonstrate the strongest evidence for efficacy. However, pimavanserin availability remains limited and long-term data are scarce. Quetiapine is widely used despite inconsistent evidence from randomized trials, largely due to its favorable safety profile and ease of use. Acetylcholinesterase inhibitors may provide benefit in selected patients, particularly those with concomitant cognitive impairment.

Current therapeutic strategies allow symptom control in many patients, yet important gaps in the evidence base persist, particularly regarding long-term outcomes. Future research should prioritize mechanistically informed therapies, standardized outcome measures, and the identification of predictors of treatment response.