What Clinicians Should Know for Managing Hallucinations in Parkinson Disease: William Ondo, MD

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"With regard to the Parkinson medicines, amantadine and dopamine agonists are probably attributed to hallucinations a little more than levodopa. But this is going to be on a case-by-case basis. Can you reduce medications? You may or may not be able to, depending on the whole picture.”

Hallucinations are a common yet possibly underdiscussed symptom of Parkinson disease (PD) in clinical practice, affecting a significant proportion of patients over the course of the condition. Many patients with PD may hide these experiences because of fear of being perceived as “crazy” or losing independence, which can potentially delay appropriate care for them. Open, nonjudgmental conversations between patients, their families, and clinicians could be essential for reducing the stigma of hallucinations. These types of discussions may help normalize these symptoms as part of the PD disease process and create a safe environment for patients to discuss their concerns with providers, potentially allowing for earlier intervention.

Although hallucinations can occur as a direct result of PD, studies have shown that they could be frequently worsened by certain medications, both used to treat PD and other unrelated conditions. Research has indicated that therapeutics such as amantadine, dopamine agonists, anticholinergics, benzodiazepines, and some antibiotics can exacerbate hallucinations. For managing PD psychosis, agents with minimal dopamine receptor blockade might be more preferred, with pimavanserin as currently the only FDA-approved option (Nuplazid; Acadia). A clinical approach that begins with addressing reversible factors and then selecting the safest pharmacologic therapy can help manage symptoms effectively without worsening motor function.

PD expert William Ondo, MD, the director of the Movement Disorders Clinic at Houston Methodist Hospital, presented on the clinical efficacy and safety of treatment options for PD psychosis at the recently concluced 4th Annual Advanced Therapeutics in Movement and Related Disorders (ATMRD) Congress, held by the PMD Alliance from June 27-30, 2025.¹ Following his presentation, Ondo spoke with NeurologyLive^® about the need for open conversations regarding hallucinations in PD and the importance of identifying as well as treating reversible contributors before modifying PD therapies. He emphasized that when pharmacologic intervention is required, clinicians should prioritize agents less likely to worsen motor symptoms, and carefully consider their evidence base, FDA approval status, and potential adverse effects.

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REFERENCES
1. Ondo W, Bembry F. The First-Line Prescription Treatment for Hallucinations and Delusions Associated With Parkinson's Disease Psychosis. Presented at: ATMRD; June 27-30, 2025; Washington, DC. Sponsored by Acadia Pharmaceuticals.