Multiple Sessions of Transcranial Direct Current Stimulation in People With Parkinson's Disease
Multiple Sessions of Transcranial Direct Current Stimulation in People With Parkinson's Disease
Parkinson's disease (PD) affects approximately 1 million people in the US, with annual health
 care costs approaching $11 billion. PD results from a loss of dopamine-producing cells in the
 brain. This decrease in dopamine is associated with shaking, stiffness, slowness,
 balance/walking problems, thinking, and fatigue which severely impair activities of daily
 living. Current medical and surgical treatments for PD are either only mildly effective,
 expensive, or associated with a variety of side-effects. Therefore, the development of
 practical and effective therapies would have significant benefits.

 Transcranial direct current stimulation (tDCS) can influence how the brain works. A review of
 studies concluded that, overall, tDCS improves walking and balance in people with PD (PwPD).
 However, these studies had mixed results. For example, most have stimulated the frontal brain
 areas and all have used intensities of 2 mA (milliamperes; a measure of electrical current
 strength) or less. However, given the vital role of the cerebellum in walking and balance,
 and in PD impairments, the cerebellum may represent a more effective brain target. A recent
 review of studies also recommended performing investigations of higher intensity tDCS
 (greater than 2 mA), to potentially increase stimulation efficacy. No study has investigated
 the effects of multiple sessions of cerebellar tDCS on gait and balance in PwPD and none have
 used tDCS intensities greater than 2 mA. Therefore, there is a critical need to determine if
 repeated sessions of cerebellar tDCS might improve walking and balance in the short- and
 long-term.
Inclusion Criteria:

 To be eligible to participate in this study, people with PD must meet the following
 criteria:

 1. Adult (50-90 yrs) with a positive diagnosis of Parkinson's disease from a movement
 disorder specialist

 2. On an unchanged regimen of dopaminergic medication for at least the last 3 months

 3. Able to independently walk for 6 min

 4. Without other severe chronic psychiatric or medical conditions

 5. Not taking any psychoactive medications

 To be eligible to participate in this study, the NH subjects must meet the following
 criteria:

 1. Adult (50-90 yrs)

 2. Able to independently walk for 6 min

 3. Without any severe chronic psychiatric or medical conditions

 4. Not taking any psychoactive medications

 Exclusion Criteria:

 An individual from either group who meets any of the following criteria will be excluded
 from participation in this study:

 1. Pregnant

 2. Known holes or fissures in the skull

 3. Metallic objects or implanted devices in the skull/head (e.g., metal plate, deep brain
 stimulator)

 4. Current or previous injuries or surgeries that cause unusual gait

 5. A score less than 24 or 17 on the Montreal Cognitive Assessment (MoCA) or
 telephone-MoCA, respectively

 Additional exclusion for PwPD:

 1. Experience freezing of gait

 2. A diagnosis of dementia or other neurodegenerative diseases

 Additional exclusion for NH subjects:

 1. A diagnosis of dementia or any neurodegenerative diseases