IBS-C Microbiome Signatures Offer Insights Into Parkinson’s-Related Constipation
Constipation-predominant irritable bowel syndrome (IBS-C) and Parkinson’s disease (PD) share features of gut dysfunction, but new research suggests they may differ in key microbiome-related metabolic pathways. Investigators comparing patients with IBS-C, PD, and healthy controls found distinct microbial and immune profiles that could help explain mechanisms underlying constipation across both disorders.
Study Findings
Researchers analyzed peripheral blood mononuclear cells (PBMCs) and gut microbiome samples from patients with IBS-C (n = 8), Parkinson’s disease (n = 18), and healthy controls (n = 21) to explore links between immune activity, gut bacteria, and constipation.
Although circulating gut-homing T-cell populations were broadly similar across groups, patients with constipation-associated PD showed a trend toward increased gut-homing immune cells. The more striking findings emerged from microbiome analyses.
Both IBS-C and PD were associated with distinct microbial taxonomic patterns compared with healthy controls, suggesting that alterations in gut bacterial communities may contribute to chronic constipation. However, microbial functional capacity differed between the two conditions.
Compared with patients with IBS-C, those with PD demonstrated significant reductions in pathways involved in tryptophan biosynthesis, polyamine production, and vitamin B metabolism. These microbial functions are important for neurotransmitter synthesis, intestinal barrier integrity, and immune regulation.
The findings indicate that while IBS-C and PD-related constipation share microbiome abnormalities, Parkinson’s disease may be characterized by additional disruptions in microbial metabolic pathways linked to neurodegeneration and gut-brain signaling.
Clinical Implications
IBS-C remains one of the most common functional gastrointestinal disorders, yet its underlying mechanisms are incompletely understood. By comparing IBS-C with Parkinson’s disease–associated constipation, the study provides new insight into which biological changes may be common to constipation itself and which may be specific to neurodegenerative disease.
The overlap in microbial alterations supports growing evidence that the microbiome plays an important role in gastrointestinal motility and symptom generation. At the same time, the reduced tryptophan, polyamine, and vitamin B metabolic pathways observed in PD suggest that Parkinson’s-related constipation may involve additional gut-brain axis mechanisms beyond those seen in IBS-C.
For gastroenterologists and other clinicians, these findings underscore the potential value of microbiome-focused approaches in chronic constipation. Future therapies targeting microbial metabolism, dietary interventions, or microbiota-directed treatments could potentially benefit patients with IBS-C while also informing strategies for PD-related gastrointestinal dysfunction.
While both conditions exhibit distinct microbiome changes, PD appears to involve greater disruption of microbial metabolic pathways, offering new clues about gut-brain interactions and potential therapeutic targets.
Reference:
Hoedt EC, Burns GL, Hedley KE, et al. Shared functional microbiome signatures in Parkinson's disease and constipation-predominant irritable bowel syndrome despite taxonomic divergence. Brain Behav Immun Health. 2026;53:101218. DOI: 10.1016/j.bbih.2026.101218
