Low Frequency Subthalamic Nucleus Deep Brain Stimulation to Improve Verbal Fluency

Study Overview
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Brief Summary
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Rationale: Parkinson's disease patients with deep brain stimulation electrodes represent a unique opportunity to study the influence of basal ganglia on neurocognitive function. Intervention: Patients' deep brain stimulators will be turned off or on and the frequency will be changed to either theta or gamma. Objectives: To identify differences in higher cognitive functions with stimulation on and off and theta versus gamma frequency stimulation. Study population: 12 patients who had previously undergone bilateral STN deep brain stimulation implantation. Study methodology: Patients will undergo four sessions of neuropsychological testing (RNGT, verbal fluency, D-KEFS CWIT) at baseline, no stimulation, theta stimulation and gamma stimulation, in random order over one day. Study outcomes: Test results of RNGT, verbal fluency, D-KEFS CWIT. Follow-up: none Statistics: Test results will be analyzed using within-subjects statistical tests.

Official Title
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Evaluation of Neurocognitive Changes in Parkinson's Disease Patients Following Acute Low Frequency Deep Brain Stimulation

Conditions
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Parkinson Disease

Intervention / Treatment
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* Device: STN DBS 10Hz
* Device: STN DBS 130Hz
* Device: STN DBS off


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male or female patients who had previously undergone bilateral STN deep brain stimulation implantation Age >18 years old Stable medication regimen for at least 3 months. Patient informed and able to give written consent Able to comply with all testing, follow-ups and study appointments and protocols Exclusion Criteria: History of epilepsy or seizure History of major substance abuse Patients with baseline settings at less than 1.5 V will be excluded from the study

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: STN DBS off<br> | Device: STN DBS off<br>* Existing DBS device turned off<br>|
| Experimental: STN DBS 10Hz<br> | Device: STN DBS 10Hz<br>* Stimulation of existing DBS device at 100Hz, with other parameters at baseline<br>|
| Active Comparator: STN DBS 130Hz<br> | Device: STN DBS 130Hz<br>* Stimulation of existing DBS device at 130Hz, with other parameters at baseline<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Delis-Kaplan Executive Function System Verbal Fluency | Number of words per category in one minute | 5-15 minutes following stimulation frequency setting change. | 
| Delis-Kaplan Executive Function System Color Word Interference Task | Time to completion of a color-word interference task | 5-15 minutes following stimulation frequency setting change. | 
| Random Number Generation | Listing of 100 numbers at 1 Hz in a random order. Evan's RNG: a measure of disproportion with which one number follows another in a sequence. Scores range from 0 (equal proportion of sequence pairs) to 1 (maximum disproportion of sequence pairs). A higher score indicates a lower randomness and poorer exective function. Count score 1: a measure of propensity to count in steps of 1. The length of each sequence with steps of 1 is squared. The total of these is summed. Scores range from 0 (no sequences with steps of 1) to 100000 (all sequences with steps of 1). A higher score indicates lower randomness and poorer exective function. Count score 2: a measure of propensity to count in steps of 2. The length of each sequence with steps of 2 is squared. The total of these is summed. Scores range from 0 (no sequences with steps of 2) to 100000 (all sequences with steps of 2). A higher score indicates lower randomness and poorer exective function. Evan's RNG, count score 1 and cou | 5-15 minutes following stimulation frequency setting change. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cognition, Hippocampus, Language, Memory, Neuromodulation, Randomized controlled trial