Transcranial Direct Current Stimulation (tDCS) and Parkinson's Disease

• Stride Length [ Time Frame: Data collection occurred before and immediately after each training session ] [ Designated as safety issue: No ]
  Stride Length was measured in centimeters
• Gait Velocity [ Time Frame: Data collection occurred before and immediately after each training session ] [ Designated as safety issue: No ]
  Gait Velocity was measured in meters per second
• Cadence [ Time Frame: Data collection occurred before and immediately after each training session ] [ Designated as safety issue: No ]
  Cadence was measured in steps per minute
• Number of Steps to Regain Balance [ Time Frame: Data collection occurred before and immediately after each training session ] [ Designated as safety issue: No ]
  Steps to regain balance were measured by the number of steps needed to recover standing balance. The steps were counted using a custom software of the motion capture system.
• First Step Length [ Time Frame: Data collection occurred before and immediately after each training session ] [ Designated as safety issue: No ]
  First step length was measured in meters from the starting position of the foot to the maximum displacement of the foot after the first step. Measurements were taken separately for forward and backward first step.
• First Step Velocity [ Time Frame: Data collection occurred before and immediately after each training session ] [ Designated as safety issue: No ]
  First step velocity was measured in meters per second

The use of low level electrical stimulation when applied over the head, also called transcranial direct current stimulation (tDCS), is being tested by several groups of researchers to see if tDCS can improve movements of persons with damage to the brain. The safety and potential benefits of tDCS to children or adults patients who are paralyzed because of brain damage are reported in the medical literature. In addition, some patients with Parkinson's disease (PD) experience improvement in memory and report better use of the hand after tDCS. The treatment requires putting electrodes (pads) over the head and sending very small amount of electrical current that the patient may feel as "little tingling". Application of tDCS takes 20 min. In this study we wish to test if tDCS application can improve stepping and walking ability of subjects with PD and if the improvement is the same as when walking on treadmill. We plan to test the subject's ability to step when pulled by a laboratory testing system and also test his/her walking ability. There will be 3 sessions 7 days apart. In the first session the subject will be tested then treated for 20 min with tDCS and then tested again. In the second session the subject will be tested then walk on a treadmill for 20 min then tested again. In the third session the subject will be tested then walk on the treadmill for 20 min while receiving also tDCS and tested one last time at the end of the session. Each session will take between 2 and 3 hours.

Recent advances in non-invasive electrical stimulation technology including transcranial direct current stimulation (tDCS) have provided novel and low risk options to rehabilitate the impaired ability of the central nervous system (CNS) to process sensorimotor information. Furthermore, tDCS appears to enhance CNS connectivity and there is preliminary evidence indicating that patients with Parkinson's Disease (PD) may experience improvement in working memory, the Unified Parkinson's Disease Rating Scale, simple reaction time and the Purdue Pegboard test. tDCS is inexpensive, portable and available for repeated home use. It may provide long-lasting enhancement of cortical activity in part because tDCS is easy to administer frequently and to combine it with other rehabilitation approaches including posture and gait training. However to date, no study has examined quantitatively the effects of tDCS on posture control and walking ability in patients with PD. As a first step we plan to identify the immediate effects of tDCS, as well as the added value of tDCS to treadmill exercise training, to improve posture and gait of individuals with PD.

• Device: Cranial Electric Stimulation (CES)
  We will follow the procedure described by several investigators as safe and effective. The participant will sit on a standard chair. Two commercially available surface electrodes will be embedded in an elastic head cup. Each electrode will be covered with a water soaked absorbent fabric. One positive (+) electrode will be placed over the primary motor cortex (M1) and pre-motor areas. One negative (-) electrode will be placed over the skin overlying the contra lateral supra-orbital region. The electrodes will be connected via 2 leads to a battery powered direct current stimulator. The stimulator will be programmed to deliver 0.975mA (peak 4mA) over 20 minutes.
• Device: Treadmill
  The participant will walk on a treadmill for 20 minutes at the individually self-selected velocity determined at baseline.
• Device: CES and Treadmill
  Participants will have a combined session with CES while walking on the treadmill for 20 minutes at the individually self-selected velocity determined at baseline.

Inclusion Criteria:

• Diagnosis of adult onset of PD
• A history of freezing of gait (FOG) as evidence by clinical assessment
• A stable regimen of anti-parkinsonian medications
• Ability to walk at least 10m without assistance
• Ability to walk on a treadmill for 20 minutes
• Personal weight of less than 500 Lb (because the suspension harness over the treadmill is limited to 500 Lb
• Stage 3 of the Hoehn and Yahr disability scale
• A score of >24 on the Mini Mental State Examination

Exclusion Criteria:

• Evidence of any clinically significant functional impairment related to cardiovascular, pulmonary, metabolic, other neurologic or musculoskeletal disease criterial that would preclude participation in training
• Any medical condition that might require other medical or surgical treatment during the study period
• A history of brain surgery or placement of a deep brain stimulator
• Dyskinesias > grade 2 on the Unified Parkinson's Disease Rating Scale (UPDRS)
• Any uncorrected vision or hearing problems that may limit daily activities or communication