Parkinson Disease and DBS: Cognitive Effects in GBA Mutation Carriers

Study Overview
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Brief Summary
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Every year, approximately 9,000 Parkinson disease (PD) patients undergo deep brain stimulator (DBS) placement into the subthalamic nucleus (STN-DBS). Studies suggest that PD patients with mutations in the glucocerebrosidase (GBA) gene are at high risk for cognitive impairment and approximately 10-17% of subjects undergoing DBS carry GBA mutations. There may be an interaction between STN-DBS, which also impairs cognitive function, and GBA, resulting in worsened cognitive function. This project will 1) determine the relationship between GBA mutation status and post-operative STN-DBS cognitive function, 2) broaden genotype-phenotype relationships of GBA mutation carriers and 3) provide scientific knowledge regarding the longitudinal cognitive effects of DBS in GBA mutation carriers through repeated neuropsychological testing.

Detailed Description
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Parkinson disease (PD) is a neurodegenerative disease affecting at least 1 million people in the U.S. Each year, 9,000 PD patients undergo deep brain stimulator (DBS) placement into the subthalamic nucleus (STN-DBS), the most commonly used basal ganglia target. Despite motor improvement, up to 50% of patients have cognitive impairment after DBS. Cognitive impairment is associated with a 2-3 fold increase in mortality, progression to dementia, and nursing home placement. At present, subjects with cognitive impairment after DBS cannot be identified pre-operatively and the effects of DBS on cognitive function are not fully understood. A specific group of PD patients, carriers of mutations in the glucocerebrosidase (GBA) gene, are at particularly high risk for cognitive impairment. PD-GBA mutation carriers have dysfunction of the glucocerebrosidase (GCase) enzyme, resulting in more rapid accumulation and spread of Lewy bodies compared with non-mutation carriers. Clinically, PD-GBA mutation carriers have: (1) deficits in visual memory due to higher Lewy body burden in hippocampal and medial temporal regions, and (2) faster progression to dementia secondary to diffuse cortical Lewy body pathology. Approximately 10-17% of PD subjects with DBS carry GBA mutations, indicating that a substantial portion of the DBS population may be susceptible to cognitive problems. Importantly, STN-DBS itself can impair cognition through modulation of the striato-anterior cingulate cortex circuit, resulting in impulsivity and more errors when faced with tasks that rely on executive functions. Therefore, the central hypothesis is that PD-GBA mutation carriers have greater global cognitive decline after STN-DBS compared with PD-GBA mutation carriers without STN-DBS, and compared with non-mutation carriers with and without STN-DBS. This is a critical area of research because if an association between GBA and STN-DBS is detected, clinicians will be able to identify subjects at risk for worsened cognitive dysfunction through genetic testing and prevent harm by: (1) recommending that PD-GBA mutation carriers avoid STN-DBS, or (2) considering an alternative DBS target such as the globus pallidus interna (GPi) that may have less cognitive side effects. The following aims are proposed: Aim 1: Determine the longitudinal changes in global cognitive function in PD-GBA mutation carriers and non-mutation carriers with and without STN-DBS; Aim 2: Determine the specific pattern of cognitive dysfunction in PD-GBA mutation carriers and non-mutation carriers with and without STN-DBS; Aim 3: Determine the differential effects of DBS on cognitive function in the ON-stimulation state vs. OFF-stimulation state, comparing PD-GBA mutation and non-mutation carriers.

Official Title
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Parkinson Disease and DBS: Cognitive Effects in GBA Mutation Carriers

Conditions
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Cognitive Decline, Parkinson, Parkinson Disease, Genetic Predisposition, GBA Gene Mutation

Intervention / Treatment
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* Other: cognitive assessments


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Parkinson's disease onset of symptoms under age 60 at least 5 years of disease with OR without deep brain stimulation Exclusion Criteria: dementia

Ages Eligible for Study
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Minimum Age: 30 Years
Maximum Age: 75 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| GBA mutation carriers without DBS<br>Parkinson's disease patients who have moderate to advanced disease but have not undergone deep brain stimulation. Subjects will be tested for GBA mutation status as part of this study. | Other: cognitive assessments<br>* Cognitive assessments will be performed at baseline, 1 year, and 2 years, depending on subject cohort placement<br>|
| non-mutation carriers without DBS<br>Parkinson's disease patients who have moderate to advanced disease but have not undergone deep brain stimulation. Subjects will be tested for GBA mutation status as part of this study. | Other: cognitive assessments<br>* Cognitive assessments will be performed at baseline, 1 year, and 2 years, depending on subject cohort placement<br>|
| GBA mutation carriers with DBS<br>Parkinson's disease patients who have moderate to advanced disease and have undergone deep brain stimulation. Subjects will be tested for GBA mutation status as part of this study. | Other: cognitive assessments<br>* Cognitive assessments will be performed at baseline, 1 year, and 2 years, depending on subject cohort placement<br>|
| non-mutation carriers with DBS<br>Parkinson's disease patients who have moderate to advanced disease and have undergone deep brain stimulation. Subjects will be tested for GBA mutation status as part of this study. | Other: cognitive assessments<br>* Cognitive assessments will be performed at baseline, 1 year, and 2 years, depending on subject cohort placement<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mattis Dementia Rating Scale | scale to assess global cognition | 2 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| NIH toolbox cognition battery | iPAD based cognitive battery | 1 year | 
| Neuro-QoL | scale to assess quality of life | 2 years | 
| PROMIS | scale to assess quality of life | 2 years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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deep brain stimulation, cognition, young onset Parkinson disease