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

• Small bowel bacterial overgrowth (SBBO) [ Time Frame: Baseline to 2 hours ] [ Designated as safety issue: No ]
  overnight fast, will ingest a solution consisting of 50 grams of glucose mixed in 150 mL of water. laboratory staff will collect end-expiratory breath samples and will analyze them for hydrogen and methane using a Quintron SC breath microlyzer
  
  

• Unified Parkinson's Disease Rating Scale (UPDRS) [ Time Frame: Baseline to 3 months ] [ Designated as safety issue: No ]
  The scale consists of 4 sections that assess behavior and mood, activities of daily living, motor symptoms, and complications of therapy. The first 3 sections comprise individual items that are rated on a 5-point scale (0 [no disability] to 4 [maximum disability]), with a maximum score of 175 for these 3 sections. Higher UPDRS scores reflect more severe disease. The fourth section of the scale is used to evaluate patients with more advanced disease who are receiving drug treatment. It takes about 15 minutes to complete.
  
  
• Gastrointestinal Symptom Severity Index (GISSI) [ Time Frame: Baseline and 3 months ] [ Designated as safety issue: No ]
  The GISSI is a validated, self-administered, multi-dimensional instrument designed to measure the frequency, severity and bothersomeness of individual GI symptoms and to provide subscale scores for interrelated symptom clusters. Factor analyses yielded 5 distinct symptom clusters that were labeled as Constipation/Difficult defecation; Abdominal Pain/Discomfort; Dyspepsia; Diarrhea/Fecal incontinence; and, GERD/Chest symptoms. It takes less than 5 minutes to complete.
  
  
• Hospital Anxiety Depression Scale (HAD) [ Time Frame: Baseline to 3 months ] [ Designated as safety issue: No ]
  The HADS is a self-administered 14-item questionnaire (seven for anxiety and seven for depression) Items are rated on a 4-point scale from 0-3. Cut-offs for identifying psychiatric distress has been reported in the literature to be >10 for anxiety and >8 for depression. It takes less than 5 minutes to complete.
  
  
• Weight change [ Time Frame: Baseline and 3 months ] [ Designated as safety issue: No ]
  Weight change after treatment
  
  
• PD-specific quality of life questionnaire (PDQ-39) [ Time Frame: Baseline and 3 months ] [ Designated as safety issue: No ]
  questionnaire designed to address aspects of functioning and well-being for those affected by Parkinson's disease. This questionnaire is based on a multi-dimensional model of health. Eight subscale scores may be derived from the items: mobility (10 items), activities of daily living (6 items), emotional well-being (6 items), stigma (4 items), social support (3 items), cognitions (4 items), communication (3 items), bodily discomfort (3 items). Patients are asked to think about their health and general well-being and to consider how often in the last month they have experienced certain events (e.g. difficulty walking 100 yards). Patients are asked to indicate the frequency of each event by selecting one of 5 options (Likert Scale): Never/occasionally/sometimes/often/always or cannot do at all.
  
  
• Paffenbarger physical activity questionnaire (PAQ) [ Time Frame: Baseline to 3 months ] [ Designated as safety issue: No ]
  measuring 1-week physical activity
  
  

• Brief Block Food Frequency Questionnaire (FFQ) [ Time Frame: Baseline to 3 months ] [ Designated as safety issue: No ]
  assess differences in macronutrient, fiber and energy intake among the study participants. This questionnaire contains a food list of about 70 food items and takes 15-20 minutes to complete.
  
  

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.