Study Links IBS to PD Changes in Microbiome

A new study has found a link between Parkinson Disease (PD) and irritable bowel syndrome (IBS), and suggests that changes in the gut microbiome may be involved. Findings suggest a more comprehensive bowel assessment that looks beyond constipation may be in order.

Results were published in the November issue of the European Journal of Neurology.¹

“To our knowledge, this is the first time increased prevalence of IBS-like symptoms and related microbiome alterations have been reported in PD patients,” wrote first author Tuomas Mertsalmi, MD, of the University of Helsinki, and colleagues.

Constipation affects most patients with PD, and is considered one the strongest risk factors for the disease. Recently, however, IBS has also been connected to PD risk.² Changes in the gut microbiome have been described both in IBS as well as in PD. That raises the question whether IBS and PD are linked through changes in gut bacteria.

To investigate, researchers conducted a case-control study in Helsinki, Finland. The study included 74 patients with PD and 75 without PD (controls). They assessed GI symptoms using standardized ROME III criteria, and non-motor symptoms using the Non-Motor Symptoms Questionnaire (NMSQuest) and Non-Motor Symptom Scale (NMSS). They also did laboratory tests to assess fecal bacteria.

Key Results:

. Significantly more IBS-like symptoms in PD vs controls (24.3% vs. 5.3%; P = 0.001)

. Almost 7 times increased risk of IBS with PD vs controls (OR 6.86, 95% CI 1.80-26.06)

. Pain and autonomic dysfunction more prevalent in PD with IBS-like symptoms vs PD without . . IBS-like symptoms

. Lower fecal abundance of Prevotella bacteria in PD with IBS-like symptoms vs PD without IBS-like symptoms

Gut microbiome changes and low-grade inflammation

The authors hypothesized that changes in the gut microbiome could cause low-grade inflammation and increased permeability of the gut mucosa. Both changes have previously been linked to IBS. Changes to the gut mucosa have also been found in PD.  Such changes may start a process of alpha synuclein neuronal degeneration in the gut that later spreads to the central nervous system.

While the results of this study suggest dysfunction of the gut-brain axis related to changes in the gut microbiome, results require confirmation in further studies. The authors suggest that a more comprehensive assessment of bowel function using either the ROME III criteria or the more recent ROME IV criteria could improve understanding of GI dysfunction in PD. 

Take Home Points

. Finnish study found that individuals with PD are at nearly 7 times increased risk of IBS

. Individuals with PD and IBS-like symptoms have lower fecal abundance of Prevotella bacteria

. This suggests a gut-brain axis disruption that may be associated with changes in the microbiome

. Further work is needed to understand the PD-IBS connection, and what role the microbiome plays in it

. More comprehensive assessments of bowel function in PD may be needed

References:

1. Mertsalmi TH, Aho VTE Pereira PAB, et al. More than constipation - bowel symptoms in Parkinson's disease and their connection to gut microbiota. Eur J Neurol. 2017;24:1375-1383. doi: 10.1111/ene.13398.

2. Lai SW, Liao KF, Lin CL, Sung FC. Irritable bowel syndrome correlates with increased risk of Parkinson’s disease in Taiwan. Eur J Epidemiol. 2014;29: 57–62.