Gut Microbiota and Tryptophan Metabolites in Parkinson's Disease

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Conditions studied: PARKINSON DISEASE (Disorder)

In brief

Parkinson's disease is a progressive neurological disorder that can also affect the digestive system. Changes in gut microorganisms and tryptophan metabolites may be associated with Parkinson's disease, but these relationships are not fully understood. This exploratory observational study will compare gut microbial communities and targeted tryptophan metabolite profiles between 15 participants with Parkinson's disease and 15 healthy controls matched by sex, age, and body mass index. Each participant will provide clinical and lifestyle information and one stool sample. Stool samples will be analyzed using 16S ribosomal RNA gene sequencing and targeted liquid chromatography-tandem mass spectrometry. The study will evaluate differences in gut microbial composition and selected tryptophan metabolites and explore their associations with constipation, bowel habits, medication use, and clinical features of Parkinson's disease. No treatment will be assigned, and participants' usual medical care will not be changed. The findings are exploratory and are intended to guide larger future studies; they cannot establish causality or be used to diagnose Parkinson's disease.

Key facts

Study ID

NCT07749261

Run by

Ningxia Medical University

People needed

30

Starts

2026-08-20

Expected to finish

2026-11-20

Last updated by the study team

2026-08-06

Who can join

Age: 45 and older, up to 90. Sex: any. Healthy volunteers: accepted.

You may qualify if…

• Participants aged 45 to 90 years, of any sex. Participants able to understand the study, provide written informed consent, and provide an acceptable stool sample according to the study procedures.
• For the Parkinson disease group: clinically established or clinically probable Parkinson disease diagnosed by a neurologist according to the Movement Disorder Society Clinical Diagnostic Criteria.
• For the Parkinson disease group: preferably a disease duration of 5 years or less and Hoehn-Yahr stage I to III.
• For the Parkinson disease group: stable antiparkinsonian medication regimen for at least 4 weeks before enrollment.
• For the healthy control group: no history of Parkinson disease, parkinsonism, or another neurodegenerative disorder and no evident parkinsonian symptoms at screening.
• Healthy controls matched individually to participants with Parkinson disease by sex, age within 5 years, and body mass index within 3 kg/m\^2

You may not qualify if…

• Use of systemic antibiotics within 3 months before stool collection. Use of probiotics, prebiotics, tryptophan, 5-hydroxytryptophan, live biotherapeutic products, or other microbiome-related supplements within 4 weeks before stool collection.
• Acute infection, fever, acute diarrhea, gastroenteritis, colonoscopy preparation, or a major dietary change within 4 weeks before stool collection.
• Active inflammatory bowel disease, celiac disease, short-bowel syndrome, gastrointestinal malignancy, or major gastrointestinal surgery within 6 months.
• Active cancer, decompensated liver or kidney disease, severe cardiovascular or hematological disease, active autoimmune disease, or current systemic glucocorticoid or immunosuppressive treatment.
• Pregnancy or breastfeeding. Long-term exclusive enteral or parenteral nutrition. Inability to provide an acceptable stool sample or essential clinical information.
• Any other condition considered by the investigator to compromise participant safety, study adherence, or interpretation of the results.

Where it is running

• Laizhou People's Hospital — Laizhou, Shandong, China

Full record on ClinicalTrials.gov

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