Gut microbiota in Parkinson’s disease: Temporal stability and relations to disease progression Original paper

What was studied?

This study investigated gut microbiome signatures in Parkinson’s disease (PD), focusing on how microbial composition changes over time and whether specific taxa—including the focus keyphrase Prevotella abundance in Parkinson’s disease—associate with disease progression. Using 16S rRNA gene sequencing, researchers analyzed stool samples collected at baseline and again 2.25 years later to determine the stability and clinical relevance of microbiome alterations in PD. The design included extensive evaluation of dietary patterns, constipation severity, medications, and other confounders known to influence gut microbial structure, allowing the team to separate PD-related alterations from other physiological or lifestyle factors.

Who was studied?

The cohort included 128 adults: 64 PD patients and 64 age- and sex-matched controls recruited from Helsinki University Hospital. A longitudinal subset of 56 PD patients contributed to the progression analyses after exclusions for deep brain stimulation, missing clinical scores, or atypical medication adjustments. Participants completed questionnaires on gastrointestinal symptoms, diet, and motor severity, along with stool sampling at both timepoints. This rigorous patient characterization supported a detailed exploration of microbe–host interactions across disease states.

Most important findings

Across taxa, the most consistent signal was reduced Prevotella and lower Prevotellaceae family abundance in PD compared with controls—a pattern replicated across both timepoints and robust to correction for constipation severity. This reduction aligns with prior PD microbiome research and highlights a taxon potentially linked to mucus integrity, short-chain fatty acid pathways, and inflammatory regulation.

Other key findings included enrichment of Akkermansia, Verrucomicrobiaceae, Bifidobacterium, and Lactobacillus, mirroring earlier reports of mucin-degrading and lactic-acid-producing taxa in PD. Enterotype analysis showed PD patients—particularly those with faster progression—were more frequently assigned to a Firmicutes-dominant enterotype. Differential abundance testing also identified families such as Ruminococcaceae and Lachnospiraceae as dominant across all subjects, though not consistently discriminatory. Prevotella/Bacteroides ratios were higher in controls, reinforcing a shift away from Prevotella-rich ecologies in PD.

Key implications

These findings underscore a reproducible and potentially clinically meaningful microbial signature in PD, with Prevotella abundance in Parkinson’s disease emerging as a candidate marker. Persistent Prevotella depletion suggests possible relevance to mucosal health, immune signaling, or microbial metabolites implicated in neuroinflammation. While progression-related microbial signatures were modest, the consistent baseline differences and robustness across confounder adjustments support future development of microbiome-informed diagnostics or therapeutic strategies. The authors emphasize the need for larger cohorts and longer follow-up to clarify causality and the mechanistic contributions of specific taxa.

Citation

Aho VTE, Pereira PAB, Voutilainen S, et al. Gut microbiota in Parkinson’s disease: reproducible differences and longitudinal dynamics. EBioMedicine. 2019;44:691-707. doi:10.1016/j.ebiom.2019.05.064