Functional bowel disorders in idiopathic Parkinson's disease: a Rome IV-based controlled study

Functional gastrointestinal disorders (FGIDs) are part of the non-motor spectrum of idiopathic Parkinson's disease (iPD). The prevalence and relevance of Rome IV-defined functional bowel disorders (FBDs) remain unclear. This study evaluated FBD prevalence and correlates in iPD using a gastroenterology-based control group.

This cross-sectional study included 64 iPD patients and 64 controls without neurological disease with Rome IV-defined FGIDs. FGIDs were assessed using the Rome IV Diagnostic Questionnaire. Non-motor symptoms, mood, and quality of life were evaluated using NMSS, Hamilton scales, PDQ-39, and GIQLI. Multivariable analyses were performed.

FBD prevalence did not differ between iPD and the FGID-enriched control group (20.3% vs. 21.9%, p = 0.828; adjusted OR 0.83, 95% CI 0.23-2.95, p = 0.774). Within iPD, FBD positivity was associated with worse PDQ-39 scores and higher non-motor burden, particularly in attention/memory and sexual domains. Anxiety severity was negatively associated with GIQLI.

In this FGID-enriched comparison, FBD prevalence was not higher in iPD. However, FBDs were associated with greater non-motor burden and poorer quality of life. These findings suggest FGIDs may be associated with variation in the non-motor phenotype rather than disease risk. Interpretation should be cautious due to control selection and demographic imbalance.