PARKINSON DISEASE (Disorder)LEAP-PARKNCT07427498
The Role of Priors in Hallucinatory Perception in Parkinson's Disease
An observational study of PARKINSON DISEASE (Disorder), run by University Hospital, Grenoble at 2 sites in France.
Trial 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… Read more about this study
- Who is it for?
- Ages 18 to 85 yearsHealthy volunteers can take part
- Conditions the study is for
- PARKINSON DISEASE (Disorder)
- How many people
- 60 participants
- Where
- 2 sitesFrance
- Study dates
- 28 Apr 2026to 27 Apr 2028
- How long will I take part?
- 1 Day
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 85 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
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.
Who may be able to join
- Adults diagnosed with Parkinson's disease (with or without visual hallucinations) or healthy volunteers.
- Age 18 - 85 years.
- Consent to participate.
Who cannot join
- 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).
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- 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.
- Post-Inclusion Exclusion:
- Participants included in the study but found to have a MoCA score below 24 will be excluded from the study.
Trial locations and contacts
2 sites in 1 country. Contact the study team or a site near you to ask about taking part.
France2 sites, 2 recruiting
- Recruiting
CHU Grenoble Alpes
Grenoble
Michael Pereira, michael.pereira@univ-grenoble-alpes.fr
Pierre Pelissier, 33+ (0)4 76 76 94 59, ppelissier@chu-grenoble.fr
- Recruiting
Grenoble University Hospitals
La Tronche
Pierre Pelissier, +33 4 76 76 94 59, ppelissier@chu-grenoble.fr
About this study
Official title: Exploratory Study on the Role of Prior Expectations in Hallucinatory Perceptions
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.
Read the detailed description
Understanding why hallucinations happen in Parkinson's disease is crucial for improving the daily lives and care of those affected. Hallucinations are common non-movement symptoms in Parkinson's that can significantly impact how people function, increase the burden on caregivers, and may signal faster cognitive decline.
Research shows that what one perceives isn't just based on what senses pick up-it's also shaped by expectations and past experiences. Sometimes, over-relying on these expectations can lead to hallucinations. However, it's still unclear whether this explains why some people with Parkinson's experience hallucinations while others don't.
In cognitive science, one way to study hallucinations is by showing people repeated trials where a stimulus is either barely visible or not present at all. The number of times someone reports seeing something when nothing is actually there (called "false alarms") has been linked to the likelihood of experiencing hallucinations in everyday life.
To explore this further, researchers use cues that hint at whether a stimulus is likely to appear. Studies have shown that healthy individuals use these cues to guide their perception. Some research even suggests that people with Parkinson's might rely on these cues more strongly, but this hasn't been directly connected to hallucinations yet.
This study aims to test whether these cues-by shaping expectations-affect the rate of false alarms more in Parkinson's patients who experience hallucinations compared to those who don't. By understanding why false alarms happen, deeper insights will be gained into visual hallucinations, as well as improved early detection, and ultimately enhanced care.
To better understand the brain mechanisms involved, brain activity will be recorded from patients who have deep-brain stimulation electrodes that allow investigators to measure neural signals in a specific brain area called the subthalamic nucleus. This could help uncover how the brain processes these expectations and perceptions.
- Conditions
- PARKINSON DISEASE (Disorder)
- Keywords
- Parkinson, hallucination, neuropsychiatry, prior
- Medical subject headings
- Parkinson Disease, Hallucinations
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| 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 |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: Baseline
Secondary outcomes (4)
Comparison of False Alarm Rates Between Parkinson's Patients Without Hallucinations and Healthy Volunteers
This outcome will test whether prior expectations (cues) affect false alarm rates more in Parkinson's disease patients without hallucinations compared to healthy volunteers. The analysis will use a generalized linear mixed model to assess the presence of an interaction effect (p < 0.05) between cue, stimulus presence, and group (patients without hallucinations vs. healthy controls).
Measured: Baseline
Impact of Prior Expectations on Perceptual Confidence in Parkinson's Disease Patients With and Without Visual Hallucinations
This outcome will evaluate whether prior expectations (cues) influence confidence levels more in Parkinson's patients with hallucinations compared to those without. Confidence ratings will be analyzed only for trials where participants report detecting a stimulus. A generalized linear mixed model will test for an interaction effect (p < 0.05) between cue, stimulus presence, and group (patients with vs. without hallucinations).
Measured: Baseline
Neuropsychological Profile Differences Between Parkinson's Patients With and Without Hallucinations
This outcome will assess whether there are significant differences in neuropsychological test scores between Parkinson's patients with hallucinations and those without. The results will be interpreted while accounting for multiple comparisons using the False Discovery Rate (FDR).
Measured: Baseline
Beta Power Differences in the Subthalamic Nucleus During False Alarms in Parkinson's Patients With Deep Brain Stimulation
This outcome will examine whether beta power (recorded via Medtronic's PERCEPT™ device) in the subthalamic nucleus differs between false alarm trials and other trials. Differences will be analyzed using a Student's t-test at each time point within a one-second window following stimulus presentation, with False Discovery Rate (FDR) correction applied to control for multiple comparisons.
Measured: Baseline
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Feb 2026
- Study start28 Apr 2026
- Primary completion27 Apr 2028 (estimated)
- Study completion27 Apr 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for PARKINSON DISEASE (Disorder)Studies of the same condition, open and under way.
- More trials run by University Hospital, GrenobleThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 60 participants (estimated)
- Target duration
- 1 Day
Sponsor and investigators
- Lead sponsor
- University Hospital, Grenoble
- Sponsor type
- University, hospital or other
- Collaborators
- INSERM U1216 Grenoble Institut des Neurosciences
- Responsible party
- Sponsor
- Investigators
- Anna Castrioto, Principal investigator, University Hospital, Grenoble
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07427498
- Sponsor's protocol ID
- 38RC25.0050
- Other IDs
- 101077874, 2025-A01842-47
- Acronym
- LEAP-PARK
- Status last verified
- Sep 2026
- First submitted
- 12 Feb 2026
- Last updated
- 30 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 30 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Exploratory Study on the Role of Prior Expectations in Hallucinatory Perceptions
- ClinicalTrials.gov ID
- NCT07427498
- Acronym / sponsor ID
- LEAP-PARK / 38RC25.0050
- Conditions
- PARKINSON DISEASE (Disorder)
- Keywords
- Parkinson, hallucination, neuropsychiatry, prior
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- University Hospital, GrenobleUniversity, hospital or other
- Collaborators
- INSERM U1216 Grenoble Institut des Neurosciences
- Study start
- 28 Apr 2026 (actual)
- Primary completion
- 27 Apr 2028 (estimated)
- Study completion
- 27 Apr 2028 (estimated)
- First posted
- 23 Feb 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
Understanding why hallucinations happen in Parkinson's disease is crucial for improving the daily lives and care of those affected. Hallucinations are common non-movement symptoms in Parkinson's that can significantly impact how people function, increase the burden on caregivers, and may signal faster cognitive decline.
Research shows that what one perceives isn't just based on what senses pick up-it's also shaped by expectations and past experiences. Sometimes, over-relying on these expectations can lead to hallucinations. However, it's still unclear whether this explains why some people with Parkinson's experience hallucinations while others don't.
In cognitive science, one way to study hallucinations is by showing people repeated trials where a stimulus is either barely visible or not present at all. The number of times someone reports seeing something when nothing is actually there (called "false alarms") has been linked to the likelihood of experiencing hallucinations in everyday life.
To explore this further, researchers use cues that hint at whether a stimulus is likely to appear. Studies have shown that healthy individuals use these cues to guide their perception. Some research even suggests that people with Parkinson's might rely on these cues more strongly, but this hasn't been directly connected to hallucinations yet.
This study aims to test whether these cues-by shaping expectations-affect the rate of false alarms more in Parkinson's patients who experience hallucinations compared to those who don't. By understanding why false alarms happen, deeper insights will be gained into visual hallucinations, as well as improved early detection, and ultimately enhanced care.
To better understand the brain mechanisms involved, brain activity will be recorded from patients who have deep-brain stimulation electrodes that allow investigators to measure neural signals in a specific brain area called the subthalamic nucleus. This could help uncover how the brain processes these expectations and perceptions.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Target follow-up
- 1 Day
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| 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 |
Who may qualify
- Ages
- 18 to 85 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- 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.
Key inclusion criteria (3 listed)
- Adults diagnosed with Parkinson's disease (with or without visual hallucinations) or healthy volunteers.
- Age 18 - 85 years.
- Consent to participate.
Key exclusion criteria (13 listed)
- 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:
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Effect of Prior Expectations on False Alarm Rates in Parkinson's Disease Patients With and Without Visual Hallucinations
Time frame: Baseline
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.
4 secondary outcomes
Comparison of False Alarm Rates Between Parkinson's Patients Without Hallucinations and Healthy Volunteers
Time frame: Baseline
Impact of Prior Expectations on Perceptual Confidence in Parkinson's Disease Patients With and Without Visual Hallucinations
Time frame: Baseline
Neuropsychological Profile Differences Between Parkinson's Patients With and Without Hallucinations
Time frame: Baseline
Beta Power Differences in the Subthalamic Nucleus During False Alarms in Parkinson's Patients With Deep Brain Stimulation
Time frame: Baseline
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Sep 2026.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Anna Castrioto principal investigator
University Hospital, Grenoble
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of PARKINSON DISEASE (Disorder), run by University Hospital, Grenoble at 2 sites in France.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 30 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in France. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Anna Castrioto, MD, PhD (+33 4 76 76 94 52, acastrioto@chu-grenoble.fr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Effect of Prior Expectations on False Alarm Rates in Parkinson's Disease Patients With and Without Visual Hallucinations (time frame: Baseline). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Sep 2026.