Summary: Researchers have identified a distinct gut microbial signature that may allow Parkinson’s disease to be detected years before motor symptoms appear. A simple stool test could eventually flag elevated risk, offering a window for early support and preventative strategies.
An international team led by University College London (UCL) examined the gut microbiome of people with Parkinson’s disease, healthy controls, and people who carry a high-risk GBA1 genetic variant but have not developed symptoms. Their analysis shows that the gut bacteria of genetically at-risk individuals already resemble an intermediate state between healthy people and those with Parkinson’s, supporting the idea that gut changes occur early in the disease process.
Key findings
- Early detection potential: Specific gut microbes appear as a warning signal years before classic Parkinson’s symptoms like tremors and stiffness.
- Consistent across populations: Results were corroborated in cohorts from the UK, Korea, and Turkey, totaling over 1,400 participants, indicating the microbial signature is consistent across different diets and cultures.
- New intervention targets: UCL-led trials are now testing whether modifying these microbial pathways — including repurposing existing medications — can slow or prevent disease progression.
Source: UCL
The study, published in Nature Medicine, used advanced metagenomic analysis of fecal samples paired with clinical data. The core finding is that around one quarter of gut microbial species (176 species) differ in abundance between people with Parkinson’s and healthy controls. Importantly, most of those same species (142) also differed in abundance between healthy controls and people who carry the GBA1 risk variant but show no clinical symptoms.
Professor Anthony Schapira (UCL Queen Square Institute of Neurology), the study’s lead investigator, emphasized the urgency of developing early detection and disease-modifying treatments: “Parkinson’s disease is a major cause of disability worldwide, and the fastest growing neurodegenerative disease in terms of prevalence and mortality. There is an urgent need to develop treatments that can stop or slow the disease’s progression.” He added that identifying people at highest risk will be essential for deploying such therapies early.
The study combined data from UCL collaborators and INRAE in France and included participants recruited at sites in the UK and Italy. The primary analysis covered 271 patients with Parkinson’s disease, 43 GBA1 variant carriers without clinical Parkinson’s symptoms, and 150 healthy controls. An independent validation set comprised additional cohorts from the UK, Korea and Turkey, adding 638 patients and 319 controls.
Analysis revealed that the gut microbiome composition of GBA1 carriers without symptoms sits between that of healthy controls and people with Parkinson’s, suggesting an intermediate or prodromal microbiome state. The abundance shifts correlated with disease stage in patients and with prodromal symptoms that are suggestive of future Parkinson’s among at-risk and some healthy individuals.
The authors caution that an altered microbiome does not guarantee someone will develop Parkinson’s. Rather, it marks an elevated risk and should be considered alongside genetics, environment, and other factors. A small fraction of healthy controls presented microbiome profiles similar to at-risk individuals, highlighting the need for further research to determine which additional factors lead to disease onset.
Participants also provided dietary data. The study observed that people with more varied, balanced diets tended to have gut profiles less associated with Parkinson’s risk, suggesting that diet modification could be a practical strategy to influence microbiome-related risk. The investigators note this as a potential avenue for prevention studies, though causal relationships remain to be confirmed.
Co-lead author Professor Stanislav Dusko Ehrlich (honorary professor, UCL Queen Square Institute of Neurology) said gut microbiome analysis could identify individuals at increased risk so they can consider lifestyle changes or other interventions aimed at reducing that risk.
UCL teams are also pursuing mechanistic work on how Parkinson’s pathology may spread from the gut to the brain and are leading clinical trials testing repurposed medications and larger programs designed to slow or halt disease progression. Funding for this study came from the Michael J. Fox Foundation for Parkinson’s Research and the UK Medical Research Council.
Key questions answered
A: No. An altered microbiome indicates an elevated risk but is only one factor among genetics and environment. The microbial signature can, however, help clinicians identify and monitor people at higher risk earlier than before.
A: The study observed that a varied, balanced diet—emphasizing fiber, fermented foods, and a wide range of plant-based foods—correlates with a healthier gut profile. Such dietary changes are a practical first step to support a resilient microbiome.
A: Evidence suggests toxic proteins linked to Parkinson’s (alpha-synuclein) may accumulate in the gut’s nervous system and travel up the vagus nerve to the brain over years. The gut may therefore reflect early pathological changes.
Editorial notes
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full by the editorial team.
- Additional context and clarification were provided by staff writers.
About this Parkinson’s disease research news
Author: Chris Lane
Source: UCL
Contact: Chris Lane – UCL
Image credit: Neuroscience News
Original research: “Microbiome signature of Parkinson’s disease in healthy and genetically at-risk individuals” by Elisa Menozzi et al., published in Nature Medicine. DOI: 10.1038/s41591-026-04318-5. Open access.
Abstract
Microbiome signature of Parkinson’s disease in healthy and genetically at-risk individuals
Parkinson’s disease (PD) is a leading cause of disability. Variants in the GBA1 gene are the most common genetic risk factor for PD and can increase lifetime risk by up to 30-fold, yet only a minority of carriers develop Parkinson’s. By combining clinical data and fecal metagenomics from patients with PD, asymptomatic GBA1 variant carriers, and healthy controls, and applying an analytic approach that assesses both differential species abundance and the coherence of those differences, the study shows that a substantial component of the gut microbiome in asymptomatic GBA1 carriers is intermediate between healthy controls and PD patients. This component correlates with disease progression and prodromal symptoms, and similar microbiome alterations were found in independent cohorts, supporting gut microbiome profiling as a potential early marker for PD development in both genetically and non-genetically at-risk individuals.