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Risk Factors for Psychosis in Parkinson’s Disease

US Neurology, 2017;13(2):78–81 DOI:


Psychosis is a characteristic neuropsychiatric symptom of Parkinson’s disease (PD) that is common and associated with worse outcomes. The purpose of this article is to review identified risk factors for visual hallucinations in PD, the most common manifestation of psychosis. With the possible exception of dopamine agonists, antiparkinsonian medications are only considered modifiers of psychosis in PD. Dementia in PD has consistently been shown to be associated with psychosis, and executive dysfunction and impairment in visual processing appear to play a role in its pathogenesis. The association of psychosis with disorders of sleep–wake dysregulation and autonomic dysfunction supports the involvement of brainstem dysfunction in PD psychosis. Despite many studies evaluating genetic risk factors for hallucinations, GBA mutations are the only variants consistently reported to be associated with an increased risk of hallucinations in PD. Lastly, psychosis in PD is associated with a more severe disease burden, both related and unrelated to PD pathology. Any explanatory model of psychosis in PD must incorporate pharmacological, neuroanatomic, pathological, and genetic factors before there can be a complete understanding of this common and disabling neuropsychiatric symptom.
Keywords: Parkinson’s disease, psychosis, hallucinations, risk factor, dementia, rapid eye movement (REM) sleep behavior disorder
Disclosure: Matthew J Barrett has received grant support from the Department of Defense and the Commonwealth of Virginia’s Alzheimer’s and Related Diseases Research Award Fund and has served as site primary investigator for clinical trials funded by the National Institutes of Health, Azevan, Axovant, and Merck. No funding was received in the publication of this article.

Authorship: All named authors meet the International Committee of Medical Journal Editors (ICMJE) criteria for authorship of this manuscript, take responsibility for the integrity of the work as a whole, and have given final approval to the version to be published.

Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any non-commercial use, distribution, adaptation and reproduction provided the original author(s) and source are given appropriate credit.
Received: May 22, 2017 Accepted: July 19, 2017
Correspondence: Matthew J Barrett, University of Virginia, Department of Neurology, PO Box 800394, Charlottesville, VA 22908, US. E:

Keywords: Parkinson’s disease, psychosis, hallucinations, risk factor, dementia, rapid eye movement (REM) sleep behavior disorder