PET-MRI of Reward System in Parkinson's Disease With RBD

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

NOT_YET_RECRUITING

Clinical Phase

NA

Total Enrollment

44 participants

Study Classification

INTERVENTIONAL

Study Start Date

2026-01-01

Study Completion Date

2029-01-01

Brief Summary

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Impulse control disorders (ICDs) are frequently observed in Parkinson's disease (PD) and can have a major functional impact on the quality of life of both the patient and their entourage. The primary risk factor for the emergence of ICDs in PD is long-term dopaminergic treatment, but other risk factors, such as rapid eye movement sleep behavior disorder (RBD), have recently been identified. The mechanisms leading to ICDs in PD remain debated, but it has been shown that the dopaminergic mesocorticolimbic pathways play a key role in reward, learning, and reinforcement processes, as well as in the regulation of impulsivity. PET studies using \[11C\]raclopride, a tracer that allows evaluation of the postsynaptic availability of dopamine D2/D3 receptors, have demonstrated abnormal sensitization of the mesocorticolimbic dopaminergic system (the reward system), particularly in the ventral striatum, in Parkinson's patients with ICDs when presented with appetitive stimuli or during gambling tasks. However, this has never been studied in patients with and without RBD. Parkinson's patients with RBD may present greater impairment of mesocorticolimbic pathways than those without RBD, particularly abnormal sensitization and postsynaptic modifications of the dopaminergic system, which could predispose patients to the emergence of ICDs when exposed to dopaminergic agonists. Confirming a particular pattern of denervation in Parkinson's patients with RBD that may favor the emergence of ICDs constitutes a personalized medicine approach with a readily identifiable risk marker in routine clinical practice and offers the possibility of adapting the management of these patients.

The main objective of this study is to investigate the availability of D2 dopaminergic receptors in subcortical structures (particularly the mesocorticolimbic system) in patients with idiopathic Parkinson's disease, depending on the presence or absence of RBD

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Detailed Description

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Conditions

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Parkinson's Disease (PD)

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

PARALLEL

Exploratory cross-sectional comparative study of pathophysiology. 2 groups will be compared :

* MPI with RBD
* MPI without RBD (control group)

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Study Groups

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MPI with RBD

Group Type EXPERIMENTAL

PET-MRI (Positron Emission Tomography - Magnetic Resonance Imaging).

Intervention Type OTHER

The PET-MRI will be performed using a Siemens Biograph mMR hybrid PET-MRI scanner. A 60-minute dynamic PET acquisition will begin following the intravenous injection of \\\[¹¹C\]raclopride (a radiotracer agonist of dopamine D2/D3 receptors) synthesized in the radiopharmaceutical laboratories of CERMEP. Simultaneously with the PET acquisition, brain MRI sequences will be acquired: 3D anatomical T1 and 3D T2, SWI, diffusion MRI (DTI), resting-state functional MRI, and arterial spin labeling (ASL) perfusion MRI.

Patients will undergo two PET-MRI scans on two consecutive days under two pharmacological conditions: Off and On dopamine:

* Day 1:\*\* The first PET-MRI session (TEPDopaOff) will be performed after a 12-hour withdrawal from usual dopaminergic treatment (Off dopamine).
* Day 2:\*\* The second PET-MRI session (TEPDopaOn) will be similar to the first, except it will take place 1 hour after administration of immediate-release Levodopa

MPI without RBD

control group

Group Type EXPERIMENTAL

PET-MRI (Positron Emission Tomography - Magnetic Resonance Imaging).

Intervention Type OTHER

The PET-MRI will be performed using a Siemens Biograph mMR hybrid PET-MRI scanner. A 60-minute dynamic PET acquisition will begin following the intravenous injection of \\\[¹¹C\]raclopride (a radiotracer agonist of dopamine D2/D3 receptors) synthesized in the radiopharmaceutical laboratories of CERMEP. Simultaneously with the PET acquisition, brain MRI sequences will be acquired: 3D anatomical T1 and 3D T2, SWI, diffusion MRI (DTI), resting-state functional MRI, and arterial spin labeling (ASL) perfusion MRI.

Patients will undergo two PET-MRI scans on two consecutive days under two pharmacological conditions: Off and On dopamine:

* Day 1:\*\* The first PET-MRI session (TEPDopaOff) will be performed after a 12-hour withdrawal from usual dopaminergic treatment (Off dopamine).
* Day 2:\*\* The second PET-MRI session (TEPDopaOn) will be similar to the first, except it will take place 1 hour after administration of immediate-release Levodopa

Interventions

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PET-MRI (Positron Emission Tomography - Magnetic Resonance Imaging).

The PET-MRI will be performed using a Siemens Biograph mMR hybrid PET-MRI scanner. A 60-minute dynamic PET acquisition will begin following the intravenous injection of \\\[¹¹C\]raclopride (a radiotracer agonist of dopamine D2/D3 receptors) synthesized in the radiopharmaceutical laboratories of CERMEP. Simultaneously with the PET acquisition, brain MRI sequences will be acquired: 3D anatomical T1 and 3D T2, SWI, diffusion MRI (DTI), resting-state functional MRI, and arterial spin labeling (ASL) perfusion MRI.

Patients will undergo two PET-MRI scans on two consecutive days under two pharmacological conditions: Off and On dopamine:

* Day 1:\*\* The first PET-MRI session (TEPDopaOff) will be performed after a 12-hour withdrawal from usual dopaminergic treatment (Off dopamine).
* Day 2:\*\* The second PET-MRI session (TEPDopaOn) will be similar to the first, except it will take place 1 hour after administration of immediate-release Levodopa

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Patients aged 45 to 80 years
* Patients diagnosed with idiopathic Parkinson's disease (PD) according to the Movement Disorder Society criteria
* Disease duration between 3 and 7 years
* Patients receiving chronic dopaminergic treatment including levodopa for at least one year to avoid tolerance issues during acute levodopa administration
* Ability to cooperate and understand, allowing strict compliance with the conditions set forth in the protocol
* Patients affiliated with or beneficiaries of a social security system
* Volunteer patients capable of providing informed consent to participate in the research

Exclusion Criteria

* Patients suffering from neurological disorders other than idiopathic Parkinson's disease (PD)
* Patients with severe depression (Beck Depression Inventory \\\[20\] (BDI) score \> 30), apathy (Starkstein scale \\\[21\] score ≥ 14), cognitive impairment (Montreal Cognitive Assessment \\\[MoCA\] \\\[22\] score \< 25), or impulse control disorders (QUIP - Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease \\\[23\], score ≥ 1)
* Patients with severe motor symptoms: patients with an MDS-UPDRS III score \> 45 will be excluded to avoid severe discomfort or interfering tremor (tremor item ≥ 3 in any body part) in the OFF state during PET-MRI acquisition. Patients with severe dyskinesias will also be excluded due to technical issues related to movement
* Patients under guardianship, curatorship, deprived of liberty, or under legal protection
* Pregnant or breastfeeding women
* Patients with contraindications to PET-MRI (e.g., those with pacemakers or insulin pumps, metallic prostheses or intracerebral clips, claustrophobia, neurosensorial stimulators or implantable defibrillators, cochlear implants, ferromagnetic ocular or cerebral foreign bodies near nervous structures, uncooperative or agitated patients, neurosurgical ventriculoperitoneal shunts, dental appliances)
* Refusal to participate

Minimum Eligible Age

45 Years

Maximum Eligible Age

80 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No