A Guide for Understanding Parkinson’s Disease Psychosis Hallucinations & Delusions

What is Parkinson’s disease psychosis?

Parkinson’s disease psychosis is a non-motor symptom of Parkinson’s disease that causes patients to experience hallucinations and/or delusions. More than half of all patients with Parkinson’s disease eventually develop symptoms over the course of their disease.1

Diagnosing and treating this condition can be complex. The condition relates to both neurology (the branch of medicine that deals with the nervous system) and psychiatry (the branch of medicine that is focused on mental and behavioral health). For this reason, Parkinson’s disease psychosis is considered a neuropsychiatric condition, since it deals with mental health symptoms (hallucinations and delusions) caused by a disease of the nervous system (Parkinson’s disease).

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What causes psychosis in Parkinson’s?

Currently, there is not a clear understanding of the exact cause of Parkinson’s disease psychosis, although certain brain chemicals and receptors (e.g. dopamine and serotonin) are believed to play a role. In general, the condition is believed to be caused by either one of the following:

Side effect of dopamine therapy:

Although an exact causal relationship has not been established, some believe that this condition may be a side effect of dopaminergic therapy (dopamine drugs are the most common treatment for Parkinson’s disease).2
Dopaminergic therapy increases dopamine levels, helping improve motor symptoms in patients with Parkinson’s disease. However, increasing dopamine levels can also cause chemical and physical changes in the brain that inadvertently lead to symptoms such as hallucinations or delusions.

Natural outcome of the disease:

This condition can be triggered by changes in the brain that occur regardless of taking dopamine­ enhancing medication. Some of these changes occur naturally as Parkinson’s disease progresses.2

Who is at risk for psychosis?

There’s no predicting with certainty which patients with Parkinson’s disease will go on to develop symptoms like hallucinations or delusions. A number of risk factors – both internal and external- are associated with the condition. Some of these risk factors include: age, duration and severity of Parkinson’s disease; and the taking of dopamine therapy.’3-6

What are the symptoms of psychosis?

Two of the most prominent symptoms are hallucinations and delusions.7 Hallucinations involve seeing, hearing, experiencing or sensing things that are not really there. Delusions are false beliefs that are not based in reality. In describing symptoms of Parkinson’s disease psychosis, patients may use such common terms as: seeing things, paranoia, flashbacks, nightmares, false beliefs, or not being in touch with reality.8

Psychosis Medication

Pimavanserin (PEA-ma-VAN-ser-in) (Nuplazid™) is approved to treat hallucinations and delusions that may develop in advanced PD. It can cause swelling of the ankles, constipation,
and confusion. Those with heart rhythm disturbances should avoid taking this medication.

Why isn’t there a greater awareness of Parkinson’s disease psychosis?

It’s not uncommon for people with Parkinson’s disease psychosis to remain silent about their experiences.2,4,9 In fact, only 10% to 20% actually report their symptoms to their physicians.4-9 Work continues to be done to raise awareness of this condition. You can find more information on the non-motor symptoms associated with Parkinson’s disease here.

How can I get help?

First and most importantly, if you find yourself experiencing symptoms such as hallucinations or delusions, speak out. It is essential to talk about your full range of Parkinson’s disease symptoms with your treatment team. A dialogue among patients, care partners, and physicians is a critical component of the effective management of your condition.


References: 1. Forsaa EB, Larsen JP, Wentzel-Larsen T, et al. A 12-year population-based study of psychosis in Parkinson’s disease. Arch Neurol. 2010;67:996-1001. 2. Ravina B, Marder I(, Fernandez HH, et al. Diagnostic criteria for psychosis in Parkinson’s disease: report of an NINOS, NIMH work group. Mov Disord. 2007;22:1061-1068. 3. Holroyd J, Currie L, Wooten GF. Prospective study of hallucinations and delusions in Parkinson’s disease.) Neural Neursurg Psychiatry. 2011;70:734-738. 4. Fenelon G, Mahieux F, Huon M, Ziegler M. Hallucinations in Parkinson’s disease: prevalence, phenomenology and risk factors. Brain. 2000;123:733-745. 5. Wolters ECh. PD- related psychosis: pathophysiology with therapeutical strategies. J Neural Transm. 2006;71:31-37. 6. Goldman JG, Holden S. Treatment of psychosis and dementia in Parkinson’s disease. Curr Treat Options Neurol. 2014;16(3): 281. 7. Goldman JG, Vaughan C, Goetz CG. An update expert opinion on management and researcl, strategies in Parkinson’s disease psychosis. Expert Opin Pharmacother. 2011; 12(13):2009-2024. 8. Data on file, ACADIA Pharmaceuticals Inc. 9. Fenelon G, Alves G. Epidemiology of psychosis in Parkinson’s disease. } Neurol Sci. 2010;289:12-17.