Striatal and Extra-Striatal Cholinergic Terminal Density in LRRK2-PD Mutation (LRRK2)

June 8, 2026 updated by: Prabesh Kanel, University of Michigan
This study explores how a specific genetic mutation of leucine-rich repeat kinase 2 (LRRK2) affects individuals with Parkinson's disease (PD), comparing those with the mutation to others with Parkinson's disease and without the mutation (iPD). Participants will complete positron emission tomography (PET) and magnetic resonance imaging (MRI) brain imaging, cognitive tests, motor tests, sensory tests, and questionnaires. The aims of this study are to compare brain chemicals in LRRK2 PD patients with iPD patients and to correlate brain chemicals with motor and cognitive tests in LRRK2 PD and iPD patients.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

LRRK2 mutations are among the most common genetic risk factors for Parkinson's Disease (PD), accounting for ~1% to 36% of familial cases depending on the ancestry, and a significant fraction of sporadic cases. These mutations are not fully penetrant, with 17-85% of carriers eventually developing PD. Among LRRK2-PD patients, clinical features manifest differently compared to idiopathic PD (iPD). LRRK2-PD patients often experience milder progression, with fewer non-motor symptoms and relatively preserved cognition, but higher likelihood of postural instability and gait difficulties (PIGD). This complex profile likely reflects the pleiotropic nature of LRRK2 effects, with mutations causing pathological increases in kinase activity and hyperphosphorylation of downstream targets. A comprehensive understanding of the protective and harmful changes induced by LRRK2 mutations remains a significant research gap.

While PD has traditionally been viewed as primarily a dopaminergic disorder, it is increasingly recognized as a multi-system condition involving other neuromodulatory systems, particularly cholinergic systems. Loss of cholinergic systems integrity is linked to dopamine-refractory symptoms, including morbid gait and cognitive impairments. Recent studies, however, demonstrate that subsets of both newly diagnosed and established PD patients exhibit upregulation of the vesicular acetylcholine transporter (VAChT), associated with preserved cognitive function, in both cross-sectional and longitudinal analyses.

A comprehensive, whole-brain investigation using the specific 18F-fluoroethoxybenzovesamicol ([18F]FEOBV) radioligand will help us better understand the nuanced whole-brain system changes in cholinergic nerve terminal integrity in LRRK2-PD compared to iPD. Our primary recruitment efforts will focus on the University of Michigan's Movement Disorder clinics, allowing us to connect with individuals diagnosed with PD who have the LRRK2 mutation. Additionally, we will work closely with PDGENEration and their sites such as Cleveland and Columbus. This collaboration will provide access to a larger pool of individuals with LRRK2 mutations, improving our ability to recruit participants for our study and ensuring a thorough investigation. We will identify regional cholinergic system alterations in PD with LRRK2 mutations. This would facilitate research on understanding the pathogenic basis for cholinergic activity alterations in iPD as well. Cholinergic systems offer multiple potential targets for pharmacologic and non-invasive neurostimulation interventions. Identification of distinctive cholinergic systems abnormalities in LRRK2-PD would provide new targets for potential therapies, initiating new approaches to experimental therapeutics in PD with LRRK2 mutations and informed by novel insights into PD pathomechanisms.

Aim 1a: To assess in vivo comprehensive, whole-brain expression and activity of cholinergic nerve terminals of LRRK2-PD patients relative to iPD patients using the [18F]FEOBV vesicular acetylcholine transporter (VAChT) radioligand.

Aim 1b: To correlate in vivo striatal and extra-striatal [18F]FEOBV regional binding with cognitive and motor assessments (esp. PIGD symptoms) in LRRK2-PD and iPD.

Aim 2a: To examine differences in striatal and extra-striatal dopamine terminal density between LRRK2-PD and iPD using the complementary PET tracer N-(3-iodoprop-2E-enyl)-2β-carbomethoxy-3β-(4-methyl-phenyl)nortropane ([¹¹C]PE2i).

Aim 2b: To investigate the association between dopaminergic function, cognition, and PIGD symptoms

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
15

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Michigan
      • Ann Arbor, Michigan, United States, 48106
        • Recruiting
        • University of Michigan
        • Principal Investigator:
          • Prabesh Kanel, PhD
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Individuals with Parkinson's disease and the LRRK2 genetic mutation.

Description

Inclusion Criteria:

  1. Male or Female, age 45 years and over.
  2. Diagnosis of PD based on the United Kingdom Parkinson's Disease Society Brain Bank Diagnostic Research Criteria (Hughes et al., 1992).
  3. Presence of LRRK2 mutation as confirmed by referral from UM Movement Disorders clinic, medical record review, or participation in the PDGENEration study.

Exclusion Criteria:

  1. Evidence of atypical parkinsonism.
  2. Contra-indications to MR imaging including but not limited to pacemakers, aneurysm clips, intraocular metal, cochlear implant, or severe claustrophobia.
  3. Evidence of large vessel stroke or mass lesion on MRI.
  4. Regular use of typical anti-cholinergic drugs or cholinesterase inhibitors.
  5. History of deep brain stimulation surgery.
  6. Pregnant or nursing.
  7. Suicidal ideation, as indicated by a response of 2 or 3 on question 9 of the Beck Depression Inventory.
  8. Cognitive impairment that results in the inability to give consent, as demonstrated by the Decision Making Capacity Tool.
  9. Any other condition or criterion that would preclude safe and meaningful participation in the study.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
LRRK2
Individuals with PD and LRRK2 genetic mutation.
iPD
Individuals with PD and without LRRK2 genetic mutation (Pre-existing cohorts, not recruiting).

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Cholinergic Differences Between leucine-rich repeat kinase 2 (LRRK2) Parkinson's disease (PD) and Idiopathic/non-LRRK2 PD (iPD)
Time Frame: Baseline
The cholinergic system changes for people with PD. It is anticipated that LRRK2-PD will demonstrate different cholinergic expression compared to iPD. 18F-fluoroethoxybenzovesamicol ([18F]FEOBV) PET scans will be used to measure Vesicular acetylcholine transporter (VAChT). Higher levels of VAChT binding indicate higher levels of acetylcholine in the brain. Lower levels of VAChT binding indicate lower levels of acetylcholine in the brain. VAChT levels will be compared across brain regions for LRRK2 vs iPD.
Baseline
Dopaminergic Differences Between LRRK2-PD and iPD
Time Frame: Baseline
The dopaminergic system changes for people with PD. It is anticipated that LRRK2-PD will demonstrate different dopaminergic expression compared to iPD. N-(3-iodoprop-2E-enyl)-2β-carbomethoxy-3β-(4-methyl-phenyl)nortropane ([¹¹C]PE2i) PET scans will be used to measure dopamine transporter (DAT). Higher levels of DAT binding indicate higher levels of dopamine in the brain. Lower levels of DAT binding indicate lower levels of dopamine in the brain. DAT levels will be compared across brain regions for LRRK2 vs iPD.
Baseline
Association of Cholinergic Data With Cognition in LRRK2-PD
Time Frame: Baseline
Association of the global average cholinergic uptake (represented by VAChT uptake) with the global average cognitive z-score of individuals with LRRK2-PD.
Baseline
Association of Cholinergic Data With Postural Instability and Gait Difficulties (PIGD) in LRRK2-PD
Time Frame: Baseline
Association of the global average cholinergic uptake (represented by VAChT uptake) with the global average PIGD score of individuals with LRRK2-PD.
Baseline
Association of Dopaminergic Data With Cognition in LRRK2-PD
Time Frame: Baseline
Association of the global average dopaminergic uptake (represented by DAT uptake) with the global average cognitive z-score of individuals with LRRK2-PD.
Baseline
Association of Dopaminergic Data With PIGD in LRRK2-PD
Time Frame: Baseline
Association of the global average dopaminergic uptake (represented by DAT uptake) with the global average PIGD score of individuals with LRRK2-PD.
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Michigan

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Michael J. Fox Foundation for Parkinson's Research

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Prabesh Kanel, PhD, University of Michigan

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 18, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 17, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 17, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
May 13, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 8, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
June 11, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 11, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 8, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • HUM00276006

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data (imaging data, clinical assessments, and neuropsychological test results) may be shared with other researchers. Data will be shared with the study sponsor (Michael J. Fox Foundation) for the purposes of contributing to Parkinson's Progression Markers Initiative (PPMI) repository. Data will be available through PPMI on a case-by-case basis upon reasonable request after the completion of the study.

IPD Sharing Time Frame

Data will be made available within 12 months of primary study completion (by September 2027) and will remain available for a minimum of 5 years.

IPD Sharing Access Criteria

Researchers seeking access to de-identified data must submit a brief research proposal to the principal investigator and execute a data use agreement in accordance with University of Michigan institutional policies or request access to the data via PPMI.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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