Effect of Levodopa on Postural Motor Learning in Parkinson Disease

Study Overview
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Brief Summary
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The primary goal of this project is to gain a better understanding of whether and how levodopa (a common anti-Parkinson disease medication) alters postural motor learning in people with Parkinson disease. A secondary goal is to assess whether motor cortical excitability, measured via Transcranial magnetic stimulation, is related to postural motor learning. Participants with Parkinson disease will complete between 50 and 100 postural perturbations (via support surface translations), ON and OFF their dopamine replacement therapy (i.e. levodopa). Adaptation of responses to these perturbations will be tracked. Participants will also undergo transcranial magnetic stimulation to capture cortical excitability of the brain (in particular the motor cortex). Cortical excitability will be correlated to adaptation of stepping (i.e. postural motor learning) ON and OFF levodopa. Investigators will also capture postural motor learning and cortical excitability in age-matched healthy adults. Investigators hypothesize that dopamine will have a negative effect on postural motor learning, and the cortical excitability will be correlated to postural motor learning.

Official Title
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Effect of Levodopa on Postural Motor Learning in Parkinson Disease

Conditions
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Parkinson Disease

Intervention / Treatment
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* Behavioral: Postural perturbation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Between 18 and 90 years of age. Individuals with Parkinson Disease Healthy adults age-matched to PD participants Participants with PD will be currently taking dopamine replacement (i.e. Levodopa) Exclusion Criteria: All subjects exclusion criteria: Deep brain stimulation Recent (within 6 months) orthopedic injuries influencing standing or balance Inability to stand independently Transcranial magnetic stimulation exclusion criteria (for the subset of individuals taking part in the Transcranial Magnetic Stimulation portion of the study): History of epilepsy or currently taking any epileptic medication, History of seizures Family history of epilepsy or seizures

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Parkinsons disease<br>Individuals with Parkinsons disease | Behavioral: Postural perturbation<br>* Participants will undergo between 50 and 100 postural perturbations (quick movements of the support surface) in multiple directions. These perturbations will be between 9 and 24cm, and between 18 and 56 cm/s depending on participant tolerance.<br>|
| Control<br>Age-matched healthy adults | Behavioral: Postural perturbation<br>* Participants will undergo between 50 and 100 postural perturbations (quick movements of the support surface) in multiple directions. These perturbations will be between 9 and 24cm, and between 18 and 56 cm/s depending on participant tolerance.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Movement of Center of Mass (COM) After Postural Perturbation | Investigators will assess (via automated and custom Matlab software) the magnitude of COM movement after a postural perturbation is delivered via motion of the support surface. This will be measured throughout the intervention, as well as at follow up (24 hour later). | Baseline and follow up (24 hours later) both ON and OFF antiparkinson medication | 
| Change in Steps After Postural Perturbation | Investigators will assess (via automated and custom Matlab software) the number of steps taken after a postural perturbation is delivered via motion of the support surface. This will be measured throughout the intervention, as well as at follow up (24 hour later). | Baseline and follow up (24 hours later) both ON and OFF antiparkinson medication | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in First Step Length | Investigators will assess (via automated and custom Matlab software) the length of the first step after a postural perturbation is delivered via motion of the support surface. This will be measured throughout the intervention, as well as at follow up (24 hour later). | Baseline and follow up (24 hours later) both ON and OFF antiparkinson medication | 
| Cortical Excitability | Investigators will assess the cortical excitability of the primary motor cortex in a subset of participants both ON and OFF levodopa. Specifically, we used transcranial magnetic stimulation to stimulate the motor cortex, where we measure muscular activity of the arm (i.e. motor evoked potentials; MEPs). The primary outcome variable noted below is the lowest stimulation setting (measured as a percentage) which results in an MEP in 5 of 10 trials. | TMS data was collected ON and OFF medication during one visit. This visit occurred within 3 weeks of the initial postural control assessments. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Parkinson Disease, Posture Balance, Dopamine, Learning