A Comparative Analysis of the Gut Microbiota in Patients With Parkinson’s Disease Worldwide: A Systematic Review

Background: Parkinson’s disease (PD) is a neurodegenerative disease associated with the gut microbiome.

Objective: Conducting a comparative analysis of the intestinal microbiome in PD patients from different geographical regions.

Methods: Two researchers conducted a systematic literature review of the Web of Science, PubMed, and Scopus databases, using specific search terms and defined inclusion and exclusion criteria to select studies. This is the first systematic review that conducted an analysis of the gut microbiota of PD patients from all continents.

Results: The α-diversity of PD patients does not differ significantly from healthy individuals in Europe and America, in contrast to Asia and Australia. β-Diversity varies among PD patients in different continents. In all regions, there has been an increase in Proteobacteria and Lactobacillaceae and a decrease in Lachnospiraceae and Roseburia. In Europe, Asia, and America, PD patients have shown an increase in Bifidobacteriaceae, Desulfovibrio, Verrucomicrobia, Bilophila, and Akkermansia and a decrease in Lachnospira. In Asia, America, and Australia, there has been a decrease in Fusicatenibacter and Lachnospiraceae ND3007, while in Europe, America, and Australia, there has been a reduction in Butyricicoccus.

Conclusions: There were no consistent patterns in the changes in α- and β-diversities of the gut microbiota among PD worldwide. Across all continents, there was an increase in Proteobacteria and Lactobacillaceae and a decrease in Lachnospiraceae and Roseburia. Despite these similar trends, there were also differences that may be attributed to factors such as ethnic background, geography, and dietary habits. These differences suggest that individualized approaches to treatment may be necessary to effectively manage PD-related gastrointestinal symptoms.