The Role of Priors in Hallucinatory Perception in Parkinson's Disease

NCT07427498 | Not Yet Recruiting

• 3 other identifiers: 38RC25.00501010778742025-A01842-47
• Study Type: observational
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this observational study is to better understand the mechanisms of hallucinations in patients with Parkinson's disease. The main question it aims to answer is: Do prior expectations increase the rate of false perceptions during a visual stimulus detection task more in Parkinson's disease patients with visual hallucinations compared to those without? Participants will undertake a computer task involving face detection and a battery of neuropsychological tests.

Conditions

PARKINSON DISEASE (Disorder)

Keywords

Parkinson; hallucination; neuropsychiatry; prior

Outcome Measures

Primary Outcomes (1)

• Effect of Prior Expectations on False Alarm Rates in Parkinson's Disease Patients With and Without Visual Hallucinations

  The primary outcome measures the false alarm rate during a visual stimulus detection task, specifically the percentage of trials in which participants report perceiving a stimulus when none was presented. The study will assess whether prior expectations (cues indicating the likelihood of a stimulus) increase false alarm rates more in Parkinson's disease patients with visual hallucinations compared to those without. The primary statistical analysis will test for an interaction effect (p \< 0.05) between cue (prior expectation), stimulus presence, and group (patients with vs. without hallucinations) using a generalized linear mixed model.

  Baseline

Secondary Outcomes (4)

• Comparison of False Alarm Rates Between Parkinson's Patients Without Hallucinations and Healthy Volunteers

  Baseline

• Impact of Prior Expectations on Perceptual Confidence in Parkinson's Disease Patients With and Without Visual Hallucinations

  Baseline

• Neuropsychological Profile Differences Between Parkinson's Patients With and Without Hallucinations

  Baseline

• Beta Power Differences in the Subthalamic Nucleus During False Alarms in Parkinson's Patients With Deep Brain Stimulation

  Baseline

Study Arms (3)

Hallucinations

Patients with Parkinson's disease with hallucinations

No hallucinations

Patients with Parkinson's disease without hallucinations

Control group

Age and sex matched group of healthy participants

Eligibility Criteria

• Age: 18 Years - 85 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

The study will recruit Parkinson's disease patients (disease duration ≥1 year, no major cognitive impairment) from CHU Grenoble-Alpes, including 15 with minor hallucinations (e.g., passage/presence sensations) and 15 with major hallucinations (e.g., complex visual hallucinations). Patients with active psychosis are excluded. Healthy volunteers (matched by age, gender, and education) will be recruited via ads in senior associations and affiliated institutions (CHUGA, GIN). Matching tolerates ±5 years for age and ±2 years for education; those without a high school diploma will be matched without strict education criteria. Ads may also appear on institutional websites.

You may qualify if:

• Adults diagnosed with Parkinson's disease (with or without visual hallucinations) or healthy volunteers.
• Age 18 - 85 years.
• Consent to participate.

You may not qualify if:

• Currently participating in another clinical or therapeutic trial involving the testing of a drug treatment.
• Inability to perform cognitive tests due to:
• Non-psychiatric (somatic) conditions likely to affect cognitive abilities. Peripheral sensory or motor deficits. Acute clinical conditions (e.g., agitation, impaired consciousness).
• Diagnosis of dementia.
• Individuals covered by Articles L1121-5 to L1121-8 of the French Public Health Code (Code de la Santé Publique), including:
• Pregnant women, women in labor, or breastfeeding mothers. Individuals deprived of liberty by judicial or administrative decision. Individuals receiving psychiatric care under Articles L. 3212-1 and L. 3213-1 (excluding those covered by Article L. 1121-8).
• Individuals admitted to a healthcare or social institution for purposes other than research.
• Minors or adults under legal guardianship or unable to express consent.
• \- Individuals with a hierarchical relationship to any professional involved in the study.
• Only for healthy volunteers:
• \- Personal history of diagnosed neurological disorders.
• \- Participants included in the study but found to have a MoCA score below 24 will be excluded from the study.

Sponsors & Collaborators

• University Hospital, Grenoble: lead
• INSERM U1216 Grenoble Institut des Neurosciences: collaborator

Study Sites (1)

Grenoble University Hospitals

La Tronche, France

Location

MeSH Terms

Conditions

Parkinson Disease; Hallucinations

Condition Hierarchy (Ancestors)

Parkinsonian Disorders; Basal Ganglia Diseases; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Movement Disorders; Synucleinopathies; Neurodegenerative Diseases; Perceptual Disorders; Neurobehavioral Manifestations; Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Officials

• Anna Castrioto

  University Hospital, Grenoble

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Anna Castrioto, MD, PhD

CONTACT

+33 4 76 76 94 52; acastrioto@chu-grenoble.fr

Michael Pereira, PhD

CONTACT

+33 4 56 52 05 69; michael.pereira@inserm.fr

Study Design

• Study Type: observational
• Observational Model: CASE CONTROL
• Time Perspective: PROSPECTIVE
• Target Duration: 1 Day
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 12, 2026
• First Posted: February 23, 2026
• Study Start: March 1, 2026
• Primary Completion (Estimated): October 1, 2028
• Study Completion (Estimated): November 1, 2028
• Last Updated: February 27, 2026

Record last verified: 2026-02

Locations

FR (1)