The Parkinson's Disease Case-Control Study

Inclusion Criteria: (For PD patients) 1. Men or women aged 50 to 75 years. 2. Clinical diagnosis of Parkinson's disease (based on MDS Parkinson's disease diagnostic criteria) 3. The patient must have at least two of the following symptoms: static tremor, bradykinesia, stiffness (which must include at least static tremor or bradykinesia); Or have asymmetrical resting tremors or asymmetrical bradykinesia. 4. Able to provide informed consent. (For healthy volunteers) 1. Age (±2 years) and sex-matched healthy control individuals for each Parkinson's disease patient. 2. Able to provide informed consent. Exclusion Criteria: (For PD patients) 1. Atypical or secondary parkinsonism due to medications (e.g., metoclopramide, flunarizine, antipsychotics) or metabolic diseases (e.g., Wilson's disease), encephalitis, or degenerative diseases (e.g., progressive supranuclear palsy). 2. The presence of clinically diagnosed dementia as determined by the investigator. 3. Previous MRI scans showed clinically significant neurological disorders (as judged by the investigator). 4. Serious illness (e.g., heart failure or malignancy). 5. Smoking more than 15 cigarettes a day and a history of alcohol or drug addiction 6. Inflammatory gastrointestinal diseases. 7. Chronic diseases that may affect the gut microorganism (e.g., diabetes, cirrhosis, or cardiovascular disease). 8. Blood or autoimmune disease, or use of immunosuppressants in the past 3 months. 9. Antibiotics have been used within 3 months prior to sample collection. 10. Chronic constipation. (For healthy volunteers) 1. Have a first-degree relative with Parkinson's disease (e.g. biological parent, sibling, or child). 2. Current or past clinically significant neurological disorders (as judged by the investigator). 3. Previous MRI scans showed clinically significant neurological disorders (as judged by the investigator). 4. Use of the following drugs in the 6 months prior to the screening visit: dopamine blockers (antipsychotics), metoclopramide, and riserpine. 5. Inflammatory gastrointestinal diseases. 6. Smoking more than 15 cigarettes a day and a history of alcohol or drug addiction 7. Chronic diseases that may affect the gut microorganism (e.g., diabetes, cirrhosis, or cardiovascular disease). 8. Blood or autoimmune disease, or use of immunosuppressants in the past 3 months. 9. Antibiotics have been used within 3 months prior to sample collection. 10. Chronic constipation. 11. Participating in other clinical trials