Parkinson’s disease is increasingly understood as a gut-brain axis disorder, and a “leaky gut” could be the doorway through which environmental triggers (bacteria, toxins, bacterial amyloids) enter the body and trigger alpha-synuclein aggregation — the hallmark pathology of PD — before it ever reaches the brain. If the intestinal barrier truly is compromised in PD, it would support the “body-first” or “gut-first” model of disease origin, opening doors to early biomarkers (detecting disease years before motor symptoms appear) and new disease-modifying treatments aimed at repairing the gut barrier (probiotics, butyrate, larazotide-type drugs). However, this review’s key finding is cautionary: existing studies are small, inconsistent, and methodologically flawed, so it’s still too early to confirm gut leakiness is a real driver of PD — meaning more rigorous tools like organoids and confocal laser endomicroscopy are needed before this can inform diagnosis or treatment
The review evaluates existing medical literature concerning intestinal permeability in Parkinson’s disease. It covers the organization of the intestinal barrier, the different paths molecules take across the gut lining, and critically analyzes the conflicting results from previous human trials. The authors point out that due to wildly inconsistent testing methodologies (e.g., distinct sugar probes, tissue staining techniques, and serum biomakers), it is too early to definitively label PD as a condition universally defined by a leaky gut. To fix this gap, they outline advanced diagnostic tools for future trials.
Diverging Experimental Results: Past studies on gut permeability in PD patients provide heavily conflicting conclusions. Some point to clear leaks, while others show no structural or functional difference compared to healthy controls.
Methodological Inconsistencies: The divergence in scientific data stems from how researchers measured “leakiness”—ranging from oral sugar absorption tests to ex vivo mucosal tissue biopsies and varied blood biomarkers.
Anatomical Variations: The paper outlines three core pathways through which gut barrier leakage can occur:
Transcellular route: Directly across the cell membrane.
Paracellular route: Through broken tight junctions (TJs) between epithelial cells.
Non-specific route: Through macroscopic damage or areas of epithelial cell loss.
The Path Forward: To resolve these conflicting results, the paper envisions and recommends adopting innovative, uniform diagnostic approaches, explicitly highlighting intestinal organoids (lab-grown mini-guts) and confocal laser endomicroscopy (real-time, microscopic imaging of the living gut wall).
Derkinderen, P., Cossais, F., Kulcsárová, K., Å korvánek, M., Sellier-Montaigne, L., Coron, E., Leclair-Visonneau, L., Cerri, S., Pellegrini, C., & Rolli-Derkinderen, M. (2025). How leaky is the gut in Parkinson’s disease? eBioMedicine, 117, 105796.
