Weight Loss in Parkinson's Disease and Role of Small Bowel Bacterial Overgrowth

The potential role of small bowel bacterial overgrowth (SBBO) in weight loss occurring in patients with Parkinson's Disease (PD) has not previously been examined. Our hypothesis was that SBBO is an important contributor to the development of weight loss in individuals with PD. The investigators proposed to 1) examine the role of SBBO in weight loss occurring in patients with PD and 2) determine the response to its treatment with a poorly absorbed antibiotic. The investigators performed a prospective, observational case-control study (Part 1) with an open-label therapeutic component (Part 2). Cases were defined as those PD patients who experienced significant weight loss while Controls were defined as those PD patients who did not experience significant weight loss.

Part 1:

Consecutive patients seen in the Parkinson's disease clinic at Mayo Clinic in Arizona were approached to participate. After the determination of their eligibility and appropriate signed informed consent, all PD patients (i.e., both Case and Control groups) underwent 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. Gastrointestinal Symptom Severity Index (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. Hospital Anxiety and Depression Scale
9. Glucose hydrogen breath test (SBBO test)
10. Qualitative assessments of smell and taste

All questionnaires were completed during the 2 hour breath test.

Part 2:

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

Eligibility Criteria:
Inclusion criteria: Parkinson's Disease

Exclusion Criteria:

1. Wheelchair-bound, akinetic individuals
2. Tube-fed individuals
3. Presence of dementia
4. Unwilling or unable to complete the tests
5. Allergic or intolerant to rifaximin
6. Presence of chronic upper or lower gastrointestinal disorders that have symptoms that may be confused with SBBO (e.g., irritable bowel syndrome, inflammatory bowel disease, celiac disease, functional dyspepsia, gastroparesis, and chronic pancreatitis)
7. Presence of prior surgery on the gastrointestinal tract except cholecystectomy, appendectomy or herniorrhaphy
8. Presence of severe concomitant acute or chronic medical condition that may interfere with the completion or interpretation of the test results
9. Women of childbearing potential. Given the age of patients with Parkinson's disease, we do not anticipate this being a large population.
10. Use of antibiotics within 1 month of breath testing