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Which antipsychotic best tames Parkinson's psychosis? a Head-to-Head trial aims to find out

NCT ID NCT04373317

Disease control Sponsor: VA Office of Research and Development Source: ClinicalTrials.gov ↗

What the study statuses mean

This study's is highlighted.

Recruitment status, easiest to join first

Recruiting now This study
This trial is taking on new participants right now.
Not yet recruiting
Registered, but not yet taking participants.
By invitation only
Not open to general applications. Only people the study team invites can take part.
Paused
Paused for now. It may or may not start again.
Ongoing
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Aug 19, 2026 · Last updated Aug 20, 2026 · Updated 1 time

Summary

This trial compares two antipsychotic drugs—pimavanserin and quetiapine—to see which is more effective and safer for treating hallucinations and delusions in people with Parkinson's disease. Up to 60% of Parkinson's patients experience psychosis, which can harm quality of life and increase caregiver burden. The study enrolls Veterans with Parkinson's disease psychosis and measures improvement in psychotic symptoms over 8 weeks. The goal is to provide clearer guidance on the best treatment option for this challenging condition.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
Pimavanserin and quetiapine, two antipsychotic medications
What this could lead to
If this trial succeeds, it could clarify which antipsychotic is more effective and safer for treating psychosis in Parkinson's disease, potentially improving quality of life and reducing caregiver burden.
What could go wrong
This is a head-to-head comparison, not a cure. Results may show one drug is only modestly better or that side effects limit benefits. Individual responses can vary, and the trial focuses on Veterans, which may not generalize to all patients.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 4

Runs after approval, following long-term safety and how well the treatment works in everyday use.

Participants

About 358 people

The number the study aims to enrol. It can still change while the study runs.

Started

Oct 2022

Expected to finish

Aug 2028

An estimate. End dates often move.

Lead sponsor

A government agency

The lead sponsor is a US federal agency other than the NIH.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

40 years and older

Sex

Anyone

Healthy volunteers

Accepted

You do not need to have the condition being studied to take part.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Veteran * Diagnosis of Parkinson's Disease consistent with UK Parkinson's Disease Society Brain Bank Clinical Diagnostic Criteria * Psychosis \[with Neuropsychiatric Inventory (NPI) hallucinations (B) or delusions (A) score 4 or greater\] * Stable dose of PD medications for at least 2 weeks * If on an acetylcholinesterase inhibitor (AChEI) initially prescribed at least 3 months prior and stable dose (no dose or medication change) for past month * Informed other must provide informed consent and agree to attend all study visits. The informed other must be at least 18 years of age and have regular contact with the patient (on average at least 4 days per week and at least 2 hours per day, or at least 3 days per week and at least 4 hours per day, that is with patient) via in-person, video, or telephone * English-speaking INFORMED OTHER * Age 18 years or older * Must have regular contact with the patient (on average at least 4 days per week, and at least 2 hours per day, or at least 3 days per week and at least 4 hours pr day, that is with patient) via in-person, video, or telephone * Agree to attend all study visits * Be able to provide informed consent * English-speaking Exclusion Criteria: * Psychosis symptoms severe enough to preclude enrollment in a clinical trial and require prompt clinical care instead * Treatment with quetiapine \>50 mg/day or pimavanserin in the past 3 months, or quetiapine 50 mg/day or another antipsychotic in the past week prior to study randomization * Deep brain stimulation (DBS) surgery within 3 months or has had stimulator adjustments in the previous 2 weeks * History of a psychotic disorder prior to PD, including bipolar disorder, schizophrenia, schizoaffective disorder, and major depressive disorder with psychotic features, if it is thought to be the cause of the current psychosis symptoms * Suspected atypical parkinsonian disorder or dementia with Lewy bodies (DLB) * Psychosis secondary to other toxic or metabolic disorder * History of long QT syndrome * Documented chart evidence indicating persistent hypoglycemia, hypokalemia, hypomagnesemia that would put patient at increased risk for QTc prolongation. * History of ventricular arrhythmias, except when treated with an implantable cardioverter defibrillator (ICD) or pacemaker, or untreated or unstable atrial fibrillation/flutter * Currently taking medications that are moderate or strong CYP3A4 inducers or strong CYP3A4 inhibitors * Concomitant use of drugs that prolong the QTc interval with a known risk of Torsades de Pointes * Comorbid medical condition determined too severe by Site Investigator to allow participation in clinical trial * Failure to tolerate quetiapine or pimavanserin previously * Severe cognitive impairment (MoCA score \<5) * Nursing home placement at screening or planned placement during the study, unless approved by study Co-Chairs. Approval will depend upon nursing facility agreement to receive, return, and administer medications or allow participant to self-administer study medications; appropriate IO availability; and transportation availability for study visits. * Currently enrolled in another therapeutic or interventional study * Pregnant, or a female of child-bearing potential who is unwilling to use a reliable form of contraception

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As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Parkinson's disease psychosis

How to take part

Only the study team decides who joins. These are the ways to reach them.

  1. The places running it

    9 sites. The list below names each one and where it is.

  2. The official record

    ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.

    Open the record ↗

  3. A doctor treating you

    A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.

Contacts and locations

Locations

  • Asheville VA Medical Center, Asheville, NC

    TERMINATED

    Asheville, North Carolina, 28805-2576, United States

  • Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA

    RECRUITING

    Philadelphia, Pennsylvania, 19104-4551, United States

  • Edward Hines Jr. VA Hospital, Hines, IL

    TERMINATED

    Hines, Illinois, 60141-3030, United States

  • Hunter Holmes McGuire VA Medical Center, Richmond, VA

    TERMINATED

    Richmond, Virginia, 23249-0001, United States

  • Lexington VA Medical Center, Lexington, KY

    TERMINATED

    Lexington, Kentucky, 40502-2235, United States

  • Louis Stokes VA Medical Center, Cleveland, OH

    RECRUITING

    Cleveland, Ohio, 44106, United States

  • Michael E. DeBakey VA Medical Center, Houston, TX

    RECRUITING

    Houston, Texas, 77030, United States

  • Minneapolis VA Health Care System, Minneapolis, MN

    RECRUITING

    Minneapolis, Minnesota, 55417, United States

  • New Mexico VA Health Care System, Albuquerque, NM

    TERMINATED

    Albuquerque, New Mexico, 87108-5153, United States

  • North Florida/South Georgia Veterans Health System, Gainesville, FL

    TERMINATED

    Gainesville, Florida, 32608-1135, United States

  • Philadelphia MultiService Center, Philadelphia, PA

    RECRUITING

    Philadelphia, Pennsylvania, 19106, United States

  • Rocky Mountain Regional VA Medical Center, Aurora, CO

    RECRUITING

    Aurora, Colorado, 80045, United States

  • San Francisco VA Medical Center, San Francisco, CA

    TERMINATED

    San Francisco, California, 94121-1563, United States

  • South Texas Health Care System, San Antonio, TX

    TERMINATED

    San Antonio, Texas, 78229-4404, United States

  • Southern Arizona VA Health Care System, Tucson, AZ

    TERMINATED

    Tucson, Arizona, 85723-0001, United States

  • St. Louis VA Medical Center John Cochran Division, St. Louis, MO

    TERMINATED

    St Louis, Missouri, 63106-1621, United States

  • Syracuse VA Medical Center, Syracuse, NY

    TERMINATED

    Syracuse, New York, 13210-2716, United States

  • Tennessee Valley Healthcare System Nashville Campus, Nashville, TN

    TERMINATED

    Nashville, Tennessee, 37212-2637, United States

  • VA Ann Arbor Healthcare System, Ann Arbor, MI

    TERMINATED

    Ann Arbor, Michigan, 48105-2303, United States

  • VA Greater Los Angeles Healthcare System, West Los Angeles, CA

    TERMINATED

    West Los Angeles, California, 90073-1003, United States

  • VA Loma Linda Healthcare System, Loma Linda, CA

    RECRUITING

    Loma Linda, California, 92357-1000, United States

  • VA Palo Alto Health Care System, Palo Alto, CA

    RECRUITING

    Palo Alto, California, 94304-1207, United States

  • VA Portland Health Care System, Portland, OR

    RECRUITING

    Portland, Oregon, 97239, United States

  • VA Puget Sound Health Care System Seattle Division, Seattle, WA

    TERMINATED

    Seattle, Washington, 98108-1532, United States

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