Parkinson’s Disease Psychosis: Common, Yet Not Often Reported

Henry Nasrallah, MD
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PD psychosis is underreported and faces treatment challenges, though a new treatment on the horizon may change that.

It may come as a surprise to clinicians that more than half of all people living with Parkinson’s disease (PD) are troubled by non-motor symptoms1 over the course of their disease. As clinicians, we’re often focused on characteristic movements such as tremor, slowness, rigidity, and walking difficulty,2 but, increasingly, we recognize that patients are also experiencing memory impairment, psychosis, depression, and vivid dreams.3,4

Parkinson’s disease psychosis (PDP) is a particularly troubling non-motor aspect of PD, as it is a risk factor for increased mortality and for long term care placement. Once placed in a nursing home for PDP, patients are likely to remain there permanently.5

The hallucinations, delusions, and paranoia that are the hallmark symptoms of PDP4 adversely impact a patient’s general emotional state and relationships with family and caregivers, and also limit their participation in daily activities. Often, patients are much more troubled by PDP than physicians may initially recognize in the clinical setting. This may be because the stigma that many PD patients and families attach to these symptoms makes them reluctant to disclose their psychotic symptoms with their psychiatrist or neurologist, or to make use of supportive services.  

In fact, only 10-20% of patients and/or caregivers ever report symptoms.6 Without education, they may not realize that psychosis is a common part of PD progression.

Elicit Symptoms Reporting

With that in mind, the health care professional must take the initiative to understand how these types of symptoms may present in PD patients. Of note, patients may be reluctant to admit that they are experiencing various hallucinations or delusions, or may attribute visual hallucinations to poor vision. Caregivers may not be aware that psychosis has emerged until it has progressed and becomes disruptive.

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The most common PDP symptom is visual hallucinations, such as the patient seeing imaginary people, animals or “creatures.” Patients aren’t necessarily alarmed by the hallucinations, but they may become frustrated when others cannot report seeing them, too. PDP patients may also experience delusional beliefs such as paranoia. In fact it is quite common for patients to accuse their spouses of infidelity or of stealing money.