Cerebellar Transcranial Direct Current Stimulation in Parkinson's Disease
Condition: Parkinson Disease; Brain Stimulation; Cerebellum
MeSH terms: Parkinson Disease
Study type: Interventional

Summary: 
      Parkinson's disease (PD) is the second most common neurodegenerative disorder and affects
      approximately 1 million people in the United States with total annual costs approaching 11
      billion dollars. The most common symptoms of PD are tremor, stiffness, slowness, and trouble
      with balance/walking, which lead to severe impairments in performing 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 add-ons to current therapeutic treatment approaches would have many
      benefits. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation
      technique that can affect brain activity and can help make long-term brain changes to improve
      functions like walking and balance. While a few initial research studies and review articles
      involving tDCS have concluded that tDCS may improve PD walking and balance, many results are
      not meaningful in real life and several crucial issues still prevent tDCS from being a useful
      add-on intervention in PD. These include the selection of stimulation sites (brain regions
      stimulated) and tDCS electrode placement. Most studies have targeted the motor cortex (brain
      region that controls intentional movement), but there is evidence that the cerebellum - which
      helps control gait and balance, is connected to several other brain areas, and is easily
      stimulated with tDCS - may be a likely location to further optimize walking and balance in
      PD. There is also evidence that certain electrodes placements may be better than others.
      Thus, the purpose of this study is to determine the effects of cerebellar tDCS stimulation
      using two different placement strategies on walking and balance in PD.

      Additionally, although many tDCS devices are capable of a range of stimulation intensities
      (for example, 0 mA - 5 mA), the intensities currently used in most tDCS research are less
      than 2 mA, which is sufficient to produce measurable improvements; but, these improvements
      may be expanded at higher intensities. In the beginning, when the safety of tDCS was still
      being established for human subjects, careful and moderate stimulation approaches were
      warranted. However, recent work using stimulation at higher intensities (for example, up to 4
      mA) have been performed in different people and were found to have no additional negative
      side-effects. Now that the safety of tDCS at higher intensities is better established,
      studies exploring the differences in performance between moderate (i.e., 2 mA) and higher
      (i.e., 4 mA) intensities are necessary to determine if increasing the intensity increases the
      effectiveness of the desired outcome.

      Prospective participants will include 10 people with mild-moderate PD that will be recruited
      to complete five randomly-ordered stimulation sessions, separated by at least 5 days each.
      Each session will involve one visit to the Integrative Neurophysiology Laboratory (INPL) and
      will last for approximately one hour. Data collection is expected to take 4-6 months. Each
      session will include walking and balance testing performed while wearing the tDCS device.
      Total tDCS stimulation time for each session will be 25 minutes.
    

Detailed description: 
      Parkinson's disease (PD) is the second most common neurodegenerative disorder and affects
      approximately 1 million people in the United States with total annual costs approaching 11
      billion dollars. The most common symptoms of PD are tremor, stiffness, slowness, and trouble
      with balance/walking, which lead to severe impairments in performing 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 add-ons to current therapeutic treatment approaches would have many
      benefits. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation
      technique that can affect brain activity and can help make long-term brain changes to improve
      functions like walking and balance. While a few initial research studies and review articles
      involving tDCS have concluded that tDCS may improve PD walking and balance, many results are
      not meaningful in real life and several crucial issues still prevent tDCS from being a useful
      add-on intervention in PD. These include the selection of stimulation sites (brain regions
      stimulated) and tDCS electrode placement. Most studies have targeted the motor cortex (brain
      region that controls intentional movement), but there is evidence that the cerebellum - which
      helps control gait and balance, is connected to several other brain areas, and is easily
      stimulated with tDCS - may be a likely location to further optimize walking and balance in
      PD. There is also evidence that certain electrodes placements may be better than others.
      Thus, the purpose of this study is to determine the effects of cerebellar tDCS stimulation
      using two different placement strategies on walking and balance in PD.

      Additionally, although many tDCS devices are capable of a range of stimulation intensities
      (for example, 0 mA - 5 mA), the intensities currently used in most tDCS research are less
      than 2 mA, which is sufficient to produce measurable improvements; but, these improvements
      may be expanded at higher intensities. In the beginning, when the safety of tDCS was still
      being established for human subjects, careful and moderate stimulation approaches were
      warranted. However, recent work using stimulation at higher intensities (for example, up to 4
      mA) have been performed in different people and were found to have no additional negative
      side-effects. Now that the safety of tDCS at higher intensities is better established,
      studies exploring the differences in performance between moderate (i.e., 2 mA) and higher
      (i.e., 4 mA) intensities are necessary to determine if increasing the intensity increases the
      effectiveness of the desired outcome.

      Prospective participants will include 10 people with mild-moderate PD that will be recruited
      to complete five randomly-ordered stimulation sessions (baseline/SHAM, unilateral tDCS
      montage at 2 mA, unilateral tDCS montage at 4 mA, bilateral tDCS montage at 2 mA, and
      bilateral montage at 4 mA), separated by at least 5 days. Each session will involve one visit
      to the Integrative Neurophysiology Laboratory (INPL) and will last for approximately one
      hour. Data collection is expected to take 4-6 months. Each session will include gait
      (30-meter walk test [30mWT], 6-minute walk test [6MWT], Timed Up and Go [TUG]) and balance
      testing (standing on a force platform with either a firm surface or a foam surface) performed
      in conjunction with one of the five randomly-ordered stimulation conditions (SHAM, unilateral
      2 mA, unilateral 4 mA, bilateral 2 mA, and bilateral 4 mA). Total tDCS stimulation time for
      each session will be 25 minutes. Gait characteristics (i.e., gait speed, stride length, step
      length, toe-off angle, etc.) and distance walked during the 30mWT and 6MWT will also be
      determined with inertial sensors (OPAL motion sensors).
    

Intervention name(s): Transcranial direct current stimulation at 2 mA; Transcranial direct current stimulation at 4 mA; Sham transcranial direct current stimulation
Intervention type(s): Device; Device; Device
Intervention description(s): Uses weak electrical current (2 mA intensity) to either increase or decrease brain excitability and improve functional or cognitive outcomes.; Uses weak electrical current (4 mA intensity) to either increase or decrease brain excitability and improve functional or cognitive outcomes.; Uses weak electrical current (2 mA intensity) at the beginning and the end of a given stimulation period to control for potential placebo-like effects or participant expectation bias.
Other intervention name(s): tDCS; tDCS; Sham tDCS
Intervention model: Sequential Assignment
Intervention model description: All participants completed all 5 randomly ordered tDCS sessions (sham, unilateral 2 mA, unilateral4 mA, bilateral 2 mA, and bilateral 4 mA.
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: transcranial direct current stimulation; walking; balance