New Drug Holds Promise to Ease Hallucinations for People with Parkinson’s

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Posted November 28, 2013

A new drug, called pimavanserin, may provide a safe and effective treatment for symptoms of psychosis, such as hallucinations, in people with Parkinson’s disease (PD), according to the results of a phase III clinical trial.  The study was published online November 1 in The Lancet.

More than half of people with PD experience symptoms of psychosis at some time during the course of the disease.  Symptoms can range from mild visual hallucinations, for example seeing stars or halos, to more troublesome delusions including paranoia or jealousy.  Most drugs that treat psychosis also block dopamine, which means they can worsen PD symptoms.  The only drugs currently available include quetiapine (Seroquel®), which has failed to show benefit in clinical trials, and clozapine (Clozaril®), which is effective but may lead to serious side effects.

A new study was carried out at 52 research centers in the United States and Canada, and led by Clive Ballard, M.D., at Kings College, London, United Kingdom.  The scientists recruited 199 study participants with moderate to severe PD who were age 40 or older.  Participants also had symptoms of psychosis that had developed after their PD diagnosis, that they experienced at least weekly, and that were severe enough to warrant treatment.

The researchers evaluated participants’ symptoms on a standard neuropsychiatric scale for delusions and hallucinations.  Then, in an effort to lessen the placebo effect (an improvement in symptoms often experienced by participants, even if they do not receive the experimental drug), all participants took part in a two-week psychosocial therapy exercise with their care partners.  Finally, half the participants took two tablets of pimavanserin once a day for six weeks; the rest took placebo pills.  Neither medical personnel nor participants knew who received which pills.


  • People who received pimavanserin showed a 37 percent improvement in their symptoms of psychosis.
  • Those who took the placebo showed a 14 percent improvement in symptoms of psychosis.
  • Care partners to the participants with PD who were receiving pimavanserin reported that caring for their partner became easier.
  • Participants who took pimavanserin slept better at night and had more awake-time during the day than those who took placebo.
  • Pimavanserin did not worsen movement symptoms.

What Does It Mean?

Better treatments are urgently needed for the psychological symptoms that can occur in PD.  Not only are these symptoms distressing, but they can lead to a person being placed in a nursing home for care.  Pimavanserin is a promising drug candidate, and this study helps advance it through the pipeline that may lead to its approval by the US Food and Drug Administration, possibly in the next few years.

Pimavanserin is the first in a new class of antipsychotic drugs being developed specifically for treating psychosis in PD.  It targets the area of the brain responsible for sensory perceptions and conscious thought.  There, it blocks certain receptors for the chemical messenger serotonin.  The results of other clinical trials suggest that pimavanserin is safe for long-term use.  Further studies are needed to directly compare its effectiveness with currently available antipsychotic medication.

Source: Parkinson’s Disease Foundation

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