Distributed structural and functional brain alterations associated with irritable bowel syndrome: a coordinate-based multimodal meta-analysis

Irritable bowel syndrome (IBS) is increasingly recognised as being associated with distributed structural and functional brain alterations, yet existing neuroimaging syntheses lack an integrated multimodal approach across imaging paradigms. To address this gap, we systematically meta-analysed IBS-related brain alterations across structural, task-free functional, and task-based functional neuroimaging studies identified through Embase, MEDLINE, PubMed, and Scopus in April 2025. Contrasts comparing IBS with non-IBS controls were synthesised using activation likelihood estimation (ALE), with sensitivity analyses restricted to standard IBS-versus-healthy-control comparisons, and robustness was evaluated through jackknife and within-paper combined-experiment analyses. In the decreased grey matter paradigm, two clusters emerged in the medial thalamus and caudate (8 contrasts, 61 foci, 380 subjects), and largely similar findings were observed in the exploratory combined grey- and white-matter analysis. Task-free analyses identified increased local-metric alterations in the postcentral gyrus (9 contrasts, 51 foci, 528 subjects), increased functional connectivity in insular and paracentral lobule/cingulate regions (15 contrasts, 104 foci, 1 187 subjects), and decreased functional connectivity in the inferior parietal lobule (10 contrasts, 56 foci, 825 subjects). Task-based analyses identified four clusters spanning cortical (insula, medial frontal gyrus) and subcortical (e.g., amygdala, putamen) regions (7 contrasts, 75 foci, 352 subjects). Together, these convergent multimodal findings indicate altered somatosensory, interoceptive, affective, and cognitive processing in IBS, providing a more comprehensive understanding of the distributed structural and functional brain abnormalities associated with the condition.