Summary: Researchers report that Parkinson’s disease — the fastest-growing neurodegenerative disorder worldwide — may be detectable long before movement symptoms appear using a simple fecal sample. The team identified a distinctive gut “microbial signature” that can appear years before tremors or stiffness, suggesting the gut microbiome is an early indicator of Parkinson’s risk.
The study focused on healthy people who carry a high-risk genetic variant (GBA1). Their gut microbiome already resembled an intermediate state between healthy individuals and people with Parkinson’s, pointing to the digestive tract as an early site of disease-related change.
Key Findings
- Early detection potential: Specific gut microbes act as an early warning signal, detectable years before classic motor symptoms emerge.
- Reproducible across populations: The microbial signature was consistent across cohorts from the UK, Korea, and Turkey, covering more than 1,400 participants and demonstrating stability across different diets and cultures.
- New treatment and prevention directions: UCL-led trials are exploring whether targeting these microbial or related immune pathways — including repurposing familiar medicines — can slow or prevent disease progression.
Source: UCL
Gut microbiome analysis can indicate elevated Parkinson’s risk before symptoms appear, new UCL-led research suggests. The research team reports that people with Parkinson’s and healthy people who carry a high-risk genetic variant (GBA1) share distinctive features in their gut microbial communities. These features were described in a new study published in Nature Medicine.
The findings could enable new screening tests based on fecal sampling to identify people at increased risk of Parkinson’s disease, allowing earlier support and preventive strategies that target the gut. The work strengthens growing evidence linking gut health and Parkinson’s, and highlights the gut microbiome as a promising biomarker for early-stage disease.
Professor Anthony Schapira (UCL Queen Square Institute of Neurology), lead investigator, emphasized the urgent need for early detection: “Parkinson’s is a major cause of disability worldwide and is increasing rapidly in prevalence. Early identification of people likely to develop the disease is essential to test and deploy treatments that might arrest or slow progression.”
The international team — led by UCL with collaborators including INRAE in France — applied an innovative analysis combining clinical data and fecal metagenomics. Their primary dataset included 271 people with Parkinson’s, 43 asymptomatic carriers of the GBA1 variant (who face an elevated risk), and 150 healthy controls.
Researchers found that roughly a quarter of gut microbial species (176 taxa) differed in abundance between people with Parkinson’s and healthy controls. Many of these same species (142 taxa) also differed between healthy controls and GBA1 carriers who had not developed symptoms. In other words, the microbiome of genetically at-risk but asymptomatic people resembled an intermediate state between healthy and affected individuals.
These microbial differences correlated with disease stage among patients and with prodromal features that indicate future Parkinson’s risk in both GBA1 carriers and some members of the general population. The team validated the signature in independent cohorts from the UK, Korea, and Turkey, adding 638 patients and 319 controls to support reproducibility.
A small subset of otherwise healthy participants showed gut microbial profiles similar to those at risk, raising the possibility that they may be on a trajectory toward Parkinson’s. The study underlines that microbiome composition is one of several interacting factors — alongside genetics and environment — that influence whether someone develops the disease.
Dietary data suggested that a varied, balanced diet was associated with a lower likelihood of hosting the risk-linked microbiome pattern. Increasing dietary fiber, fermented foods, and plant diversity may support a microbiome that resists disease-related changes, indicating a potential route for prevention through nutrition.
Co-lead author Professor Stanislav Dusko Ehrlich (UCL) noted: “Analyzing the gut microbiome could identify people at elevated risk of Parkinson’s so they may take preventive steps, such as dietary adjustments, and enter monitoring or early-intervention trials.”
Other UCL work has described how Parkinson’s-related proteins may travel from the gut to the brain via immune pathways, offering further clues to intervention points. UCL investigators are also leading genetically stratified clinical trials, including a phase 3 trial testing a common cough medicine as a candidate therapy and the world’s largest ongoing trial of treatments aimed at slowing or stopping Parkinson’s progression.
Funding: The study was supported by the Michael J. Fox Foundation for Parkinson’s Research and the Medical Research Council.
Key Questions Answered:
A: No. An at-risk microbiome signals an elevated probability, not a certainty. Parkinson’s arises from multiple interacting causes, including genetics and environmental factors. Microbiome screening can, however, identify people for earlier monitoring and preventative strategies.
A: The study linked a diverse, balanced diet with a healthier gut profile. Increasing fiber, eating fermented foods, and consuming a wide variety of plant-based foods generally supports microbial diversity and may reduce the presence of disease-linked patterns.
A: Research suggests that toxic proteins associated with Parkinson’s, such as alpha-synuclein, may form in the gut’s nervous system and travel to the brain via the vagus nerve over many years, making the gut an early site of detectable change.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by staff.
About this Parkinson’s disease research news
Author: Chris Lane
Source: UCL
Contact: Chris Lane – UCL
Image: The image is credited to Neuroscience News
Original Research: Open access. “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
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 risk up to 30-fold, yet only around 20% of carriers develop the disease. By combining clinical and fecal metagenomics from patients with PD, asymptomatic GBA1 carriers, and healthy controls, the study shows that approximately 25% of the gut microbiome in GBA1 carriers occupies an intermediate state between healthy controls and PD patients. This microbiome component correlates with disease progression and prodromal signs predictive of PD. Similar alterations were observed in independent cohorts from the United States, Korea, and Turkey, supporting the idea that gut microbiome changes can identify both genetically and non-genetically at-risk individuals and serve as an early marker of disease development.