Clinical Trials

Hypothesis:  Small bowel bacterial overgrowth is an important contributor to the development of weight loss in individuals with Parkinson's disease.

     Specific aims:  1) To determine the prevalence of SBBO in consecutive patients seen in a Parkinson's disease specialty clinic, and 2) To evaluate the effect of SBBO treatment in PD patients with weight loss.

     Study design:  Prospective, observational case-control study with open-label therapeutic component.  Cases will be defined as those PD patients who've experienced significant weight loss while Controls will be defined as those PD patients who have not experienced significant weight loss.

     Part 1:

     Consecutive patients seen in the Parkinson's disease clinic at MCA will be approached to participate.  After the determination of their eligibility and appropriate signed informed consent, all PD patients (i.e., both Case and Control groups) will undergo the following:

       1. Assessment of demographic features, weight history and PD history

       2. PD and other medications

       3. Determination of PD severity using the Unified Parkinson's Disease rating scale

       4. Evaluation of gastrointestinal symptoms (GISSI and modified GISSI)

       5. Determination of usual calorie and nutrient intake (Brief Block Food Frequency Questionnaire)

       6. Paffenbarger physical activity questionnaire

       7. Quality of life (SF12 and PD-specific)

       8. HAD survey

       9. Glucose hydrogen breath test (SBBO test)

      10. Qualitative assessments of smell and taste

     All questionnaires will be completed during the 2 hour breath test.

     Part 2:

     All individuals in the weight loss group (i.e., only the Case group) will be offered open-label treatment with the poorly absorbed antibiotic, rifaximin, 550 mg PO BID for 14 days.  Treatment will not depend upon the results of the bacterial overgrowth breath test. Thus, both normal and abnormal breath test subjects will receive antibiotic treatment.  The patient will be contacted by phone 1 month after treatment at which time the presence of GI symptoms will be determined and inquiry made about any adverse effects related to rifaximin use.  GI symptoms, quality of life, weight measurement and breath testing will be repeated at a 3 month study visit.

In this study, the investigators will monitor extracellular neurotransmitter levels using a probe that is able to perform real time electrochemical detection during deep brain stimulation surgery. The overall question this study is designed to answer is: Are there neurotransmitters released during deep brain stimulation?