Gamma Sensory Flicker for Parkinson's Disease Patients With Freezing of Gait

This study aims to answer the question: to assess the safety, and tolerability of gamma light in Parkinson's disease (PD) patients with freezing of gait (FOG).

Parkinson's disease (PD) patients often experience a complex gait disorder known as Freezing of Gait (FOG). FOG is characterized by brief arrests of stepping when initiating gait, turning, and walking straight and patients describe it as their feet being "glued" to the floor. FOG in Parkinson's disease (PD) is a considerable public health burden worldwide. It is a poorly understood gait symptom that has potentially grave consequences as FOG is intermittent and unpredictable, a leading cause of falls with injury, and results in loss of independence. FOG is generally found to be associated with cognitive decline, particularly executive dysfunction which, in turn, has been associated with higher spinal fluid amyloid (Aβ42) levels in PD.

There is data linking amyloid to FOG. A previous study showed that the gamma light helped reduce some amyloid. The research team is studying if gamma light exposure for 1 hour daily is well tolerated. Also, does it have any effect on freezing of gait severity?

This will be a sham-controlled study with one group receiving the sensory stimulation and the other receiving sham stimulation.

Exposure will be provided by wearing a pair of glasses and headphones. Both of these will be connected to a device that will provide light and sound during the daily 1-hour session.

Gamma light appeared in a previous study to have potential as a non-invasive, non-medication approach to reduce amyloid from the brain. This study will investigate if the link between amyloid and FOG can be changed and improve FOG.

Gamma is a short wavelength of light and/or sound between 25-140Hz. Previous research suggested that 40Hz can potentially activate cells in the brain to remove amyloid. Amyloid is a protein that forms in the spaces between nerve cells in the brain in diseases such as Alzheimer's and Parkinson's disease.

This study also has two optional parts. One option is to undergo two lumbar punctures at the baseline and Month 6 visits. The other option is to participate in a one-year extension of the study. Blood draws will be used to verify levodopa levels in the blood during both the ON and OFF Parkinson's disease medication states.

Optional lumbar punctures will be performed at baseline and 6 months to collect cerebrospinal fluid (CSF) samples which will be analyzed for change in amyloid levels before and after treatment. An electroencephalogram (EEG) will be utilized at the beginning of the study to evaluate the brain's response to the stimulus. Cognitive testing will be administered to capture any cognitive changes. Questionnaires used will provide any changes to the participant's self-evaluation.

The duration of the blinded portion is approximately 7 months. The optional extension portion will have two in-clinic visits at month 12 and month 18. Participants will be enrolled from the Emory University movement disorder clinic.

Eligibility Criteria:
Inclusion Criteria:

* PD Diagnosis by UK Brain Bank Criteria
* Hoehn \& Yahr stage I-IV in the off-state
* FOG noted in medical history
* FOG confirmed visually by the examiner in the office
* PD that is levodopa-treated and responsive
* Able to manage 12 hours of "OFF" dopaminergic medication state
* Age 50-75 years
* Able to sign a consent document and willing to participate in all aspects of the study

Exclusion Criteria:

* A diagnosis of atypical parkinsonism including vascular parkinsonism
* Prior treatment with medications that cause Parkinsonism
* Stage V PD -unable to walk independently when OFF
* Absence of levodopa response
* Neurological or orthopedic disorders interfering with gait
* Dementia precluding completing study protocol including those meeting criteria for dementia with Lewy bodies
* Major depression based on the Diagnostic and Statistical Manual of Mental Disorders (DSM V) criteria
* Any medical problems that would preclude participation, including individuals with a history of migraines, tinnitus, or seizures because sensory stimuli can potentially exacerbate these conditions.
* Profound sensory loss as determined by the investigator.