Fecal microbiota transplantation in Parkinson's disease: a systematic review.

INTRODUCTION

Current Parkinson's disease (PD) treatments offer limited, temporary relief. Fecal microbiota transplantation (FMT) is a potential therapy, but its safety and efficacy remain unclear.

METHODS

PubMed, Scopus, Cochrane Library, and Web of Science were searched on 20 July 2026. Eligible studies included adults with PD receiving FMT reporting motor and non-motor outcomes. Study quality was assessed using Joanna Briggs Institute checklists and Cochrane RoB 2. Due to heterogeneity, results were synthesized narratively.

RESULTS

Fourteen studies (nine trials, three case series, two case reports; 369 participants) were included. FMT protocols varied in stool preparation, delivery route, regimen, and follow-up (3-12 months). Four of six trials reported modest, short-term motor improvements. Non-motor benefits, mainly gastrointestinal function, sleep, and mood, were inconsistent. Microbiota analyses showed partial or temporary restoration toward healthy profiles. FMT was generally safe, with mainly mild, transient adverse events. Risk of bias varied: two high, four some concerns, one low.

CONCLUSIONS

FMT appears safe and may provide short-term improvements in select motor and gastrointestinal outcomes in PD. Evidence is limited by small samples, heterogeneity, and methodological weaknesses. Well-designed, adequately powered RCTs with standardized protocols are needed to determine its therapeutic and disease-modifying potential.

REGISTRATION: PROSPERO (CRD42024508462).