Neurobiological Drivers of Mobility Resilience: The Dopaminergic System

NCT ID: NCT04325503

Last Updated: 2024-04-04

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: PHASE1/PHASE2
• Total Enrollment: 14 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2021-02-08
• Study Completion Date: 2022-06-30

Brief Summary

Walking with age becomes both slower and less 'automated', requiring more attention and brain resources. As a result, older adults have a greater risk of negative outcomes and falls. There is an urgent need to identify factors that can help compensate for these harmful factors and reduce walking impairments, as there are currently no effective treatments available. Investigators have recently discovered that ~20% of older adults maintain fast walking speed even in the presence of small blood vessel brain changes and leg problems, thus appearing to be protected against these harmful factors. The investigators work suggests that the brain dopamine (DA) system may be a source of this protective capacity. Investigators have also shown that lower levels of dopamine are associated with slow walking. Investigators will be investigating the role of dopamine on slow walking and other parkinsonian signs using detailed clinical assessment, assessment of dopamine activity, and clinical interventions.

Detailed Description

Walking with age becomes both slower and less 'automated', requiring more attention and prefrontal resources. As a result older adults have a greater risk of adverse mobility outcomes and falls. Walking disturbances in the elderly have been linked to changes in both cerebral, in particular small vessel disease (cSVD), and peripheral systems. There is an urgent need to identify factors that can help compensate for these harmful factors and reduce walking impairments, as there are currently no effective treatments available. Although effective mobility is the end result of the functional capacity of both central and peripheral systems, the brain's unique modulatory and adaptive capacity may provide clues for novel interventions. For example, investigators have recently discovered that ~20% of older adults maintain fast walking speed even in the presence of age related cSVD and peripheral system impairments, thus appearing resilient to these harmful factors. The investigators work suggests that the nigrostriatal dopamine (DA) system may be a source of this resilience. As investigators recent findings suggest, DA neurotransmission positively predicts walking speed; it also attenuates the negative effects of age related cSVD and peripheral system impairments on walking speed. These findings are consistent with post-mortem evidence that a combination of loss of nigral DA neurons and cSVD best predict age-related walking impairment. The nigrostriatal DA system plays a critical role in motor control; nigrostriatal. DA neurotransmission regulates the automated execution of overlearned motor tasks via its connections with sensorimotor cortical and subcortical areas.

The investigators hypothesize that higher nigrostriatal DA neurotransmission drives resilience to cSVD and peripheral system impairments, via higher connectivity of sensorimotor networks, thus increasing automaticity of walking and reducing prefrontal engagement while walking. Unlike cSVD and brain structural impairments, DA neurotransmission is potentially modifiable, thereby offering novel approaches to treat non-resilient elderly in a targeted fashion. This translational pilot study will use a biomechanistic target engagement study in older adults with slow walking and/or other parkinsonian signs.

The study will include elderly men and women age 60 or older with evidence of mild parkinsonian signs (MPS, or slow gait (< 1m/s)) and/or additional cSVD on brain MRI.

Conditions

Parkinsonian Signs in Older Persons

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: OTHER
• Blinding Strategy: NONE

Study Groups

Treatment

carbidopa and carbidopa-levodopa treatment for parkinsonian signs in older persons using standard dosing, frequency for a duration for 1-2 weeks

Group Type: EXPERIMENTAL

carbidopa

Intervention Type: DRUG

carbidopa and carbidopa-levodopa standard treatment

Interventions

carbidopa

carbidopa and carbidopa-levodopa standard treatment

Intervention Type: DRUG

Other Intervention Names

carbidopa-levodopa

Eligibility Criteria

Inclusion Criteria

1. Age 60 or older (M/F)

2. Evidence of mild parkinsonian signs (incl. slow gait (< 1m/s))

Exclusion Criteria

1. Presence of clinically significant degenerative joint disease and/or neuropathy interfering with proper assessment of the motor UPDRS exam.

2. Presence of significant dementia.

3. Evidence of a large vessel stroke in a clinically relevant area (cerebral cortex, basal ganglia, thalamus) or mass lesion on structural brain imaging (MRI).

4. Participants in whom magnetic resonance imaging (MRI) is contraindicated including, but not limited to, those with a pacemaker, presence of metallic fragments near the eyes or spinal cord, or cochlear implant.

5. Severe claustrophobia precluding neuroimaging procedures.

6. Hypersensitivity to the carbidopa, levodopa, and tablet components.

7. Any other medical history determined by investigators to preclude safe participation.

• Minimum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

National Institute on Aging (NIA)

NIH

Sponsor Role: collaborator

University of Michigan

OTHER

Sponsor Role: lead

Responsible Party

Nicolaas Bohnen, MD, PhD

Principal Investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Nicolaas Bohnen, MD

Role: PRINCIPAL_INVESTIGATOR

University of Michigan

Locations

Functional Neuroimaging, Cognitive, and Mobility Lab, University of Michigan

Ann Arbor, Michigan, United States

Countries

United States

Provided Documents

Document Type: Study Protocol and Statistical Analysis Plan

View Document

Document Type: Informed Consent Form

View Document

Other Identifiers

5U01AG061393-05

Identifier Type: NIH

Identifier Source: secondary_id

View Link

HUM00156490

Identifier Type: -

Identifier Source: org_study_id