Activation likelihood estimation of convergent resting-state brain alterations in diarrhea-predominant IBS: a systematic review and meta-analysis.

BACKGROUND

Diarrhea-predominant irritable bowel syndrome (IBS-D) is a common functional gastrointestinal disorder. Resting-state functional magnetic resonance imaging (rs-fMRI) has provided valuable insights into brain activity alterations; however, despite the increasing number of neuroimaging studies, the results remain inconsistent. This study aimed to perform a coordinate-based activation likelihood estimation (ALE) meta-analysis to identify functionally impaired brain regions showing convergent alterations in IBS-D.

METHODS

Coordinate-based ALE was applied to rs-fMRI studies of IBS-D that were systematically retrieved from multiple databases. Statistical significance was determined using cluster-level family-wise error correction, and the robustness of the results was further evaluated through a jackknife sensitivity analysis.

RESULTS

The ALE meta-analysis revealed two clusters of hyperactivity in IBS-D patients compared to healthy controls (HCs). The first cluster was located in the right cerebellar culmen (69.4%), extending to the right cerebellar lingula (7.7%) and left fastigial nucleus (22.9%). The second cluster was located in the right parahippocampal gyrus [78.6%, Brodmann area (BA) 36], extending to the right fusiform gyrus (18.6%) and right sub-gyral area of the parahippocampal gyrus (2.8%). In contrast, one cluster of hypoactivity was observed in the right superior frontal gyrus (67.6%, BA 10) and right middle frontal gyrus (32.4%, BAs 9 and 10). The jackknife sensitivity analysis confirmed the robustness of these clusters across all iterations.

CONCLUSIONS

This ALE meta-analysis identified functionally impaired brain regions consistently altered in IBS-D, providing novel insights into its central mechanisms and potential targets for future research and therapeutic interventions.