A Pilot Study Assessing Impulsivity in Patients With Huntington's Disease on Xenazine (Tetrabenazine)

Study Overview
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Brief Summary
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The purpose of this research study is to see if tetrabenazine, which is commonly used to treat Huntington's Disease (HD), reduces the problems of impulsivity that are common in patients with HD. Investigators will also see how the medicine affects aspects of thinking and mood.

Detailed Description
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This study is an open-label assessment of behavioral symptoms including depression, impulsivity, and suicidal ideations in patients prior to, and after, taking a stable dose of TBZ for Huntington's disease. All subjects will be evaluated with tests of depression (Beck Depression Scale), impulsivity (QUIP, BIS-11, and computerized impulsivity scales), and suicidal ideation (Columbia Suicide Scale) as a safety measure before they actually start taking TBZ. Since there is a significant lack of awareness of emotional and cognitive symptoms (anosagnosia) in patients with HD, collateral sources will be asked to fill out similar questionnaires based on their knowledge and observation of the patient. Patients and collaterals will be asked to return to the clinic for an identical evaluation plus adverse events, after they have been on a stable dose of TBZ for 4 weeks, which would be 8 ± 1 week after initiating TBZ. Patients will be titrated over 3-5 weeks to best dose as determined by the investigator, up to a maximum of 75 mg/day. As patients are titrating, there will be several telephone contacts conducted. The initial dose will be 12.5 mg BID. Best dose will be largely determined by adverse events and subjective efficacy. Determination of best dose will include two scheduled phone calls and others as needed. Other medications will remain stable between visits.

Official Title
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A Pilot Study Assessing Impulsivity in Patients With Huntington's Disease on Xenazine (Tetrabenazine)

Conditions
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Huntington's Disease

Intervention / Treatment
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* Drug: Tetrabenazine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: For HUntington's Disease (HD) patients only--Definite HD as indicated by positive gene testing or typical symptoms in the context of family history of HD. A moderate degree of impulsivity as measured by the Barrat Impulsivity Scale (BIS). (>65) Must be symptomatic in the opinion of the investigator. Standard clinical criteria for symptomatic HD will be employed, any motor signs c/w HD, usually chorea. Patient is cognitively alert and able to answer/understand. Exclusion Criteria: Patient requires the assistance of another person to walk, or is non-ambulatory. Patient is severely impaired cognitively. Patients taking neuroleptic (dopamine blocking) medications within the past 14 days. patient is actively suicidal, has untreated or inadequately treated depression, has impaired hepatic function, is taking MAO inhibitors or is taking reserpine or has been off of reserpine for less than 20 days

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Tetrabenazine<br>Xenazine (tetrabenazine), pill, dosage titrated to effect, three times a day, 12 weeks | Drug: Tetrabenazine<br>* Xenazine, pill, dose to effect, three times a day, for 12 weeks<br>* Other names: Xenazine;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Score on the Questionnaire for Impulsive Disorders in Parkinson's Disease | A newly developed and tested tool for measuring impulsivity in PD patients. | Baseline and 8 weeks | 
| Change in Score on the Geriatric Depression Scale | This assessment detects depressive symptoms in subjects and is a commonly used neuropsychological scale. It is less influenced by motor / somatic symptoms compared to other depression scales. | Baseline and 8 weeks | 
| Change in Score on the Barrat Impulsivity Scale | Scale is the most widely used self-report measure of impulsive personality traits. The BIS-11 is a 30-item self-report questionnaire that is scored to yield a total score, three second-order factors, and six first-order factors. | Baseline and 8 weeks | 
| Change in Score on the Minnesota Impulsivity Disorders Interview | This is a clinician-administered screening instrument that had shown good reliability and validity in studies of adult and adolescent psychiatric patients. | Baseline and 8 weeks | 
| Change in Score on the Iowa Gambling Task | a widely used, but complex, neuropsychological task of executive function in which mixed outcomes (gains and losses) are experienced together, to performance on a relatively simpler descriptive task, the Cups task, which isolates adaptive decision making for achieving gains and avoiding losses. It is very predictive of impulsive personality traits | Baseline and 8 weeks | 
| Change in Score on the Montreal Cognitive Impairment Assessment | cognitive screening test designed to assist Health Professionals for detection of mild cognitive impairment, including Alzheimer's disease. | Baseline and 8 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Score on the United Huntington's Disease Rating Scale - Motor section | A clinical examination of various cognitive, behavioral, and motor features commonly seen in patients with HD (Huntington Study Group, 1996). This is a standardized test used in most clinical studies of HD. | Baseline and 8 weeks |