Irritable bowel syndrome and structural brain changes - A two-sample Mendelian randomization study of cortical thickness and surface area.

Researchers investigated whether irritable bowel syndrome (IBS) is connected to physical changes in brain structure. Using a sophisticated genetic analysis method called Mendelian randomization, scientists examined data from over 51,000 people of European ancestry to see if IBS affects the thickness and surface area of different brain regions. The study found five significant associations between IBS and brain structure changes. People with IBS showed increased surface area in two brain regions: the inferior temporal area (involved in visual processing and memory) and the rostral anterior cingulate (important for emotional regulation). The researchers also found that IBS was linked to increased thickness in two regions called the isthmus cingulate and pars opercularis, which are involved in emotional processing and language. Interestingly, one area—the rostral anterior cingulate—showed decreased thickness despite having increased surface area. These findings are important because they provide biological evidence for what many IBS patients experience: the connection between gut symptoms and mental health challenges like anxiety and depression. For patients considering acupuncture treatment for IBS, these results support the brain-gut connection that traditional Chinese medicine has long recognized. Acupuncture may help address both the physical digestive symptoms and the neurological aspects of IBS by working on this interconnected system. To explore acupuncture for IBS management, seek treatment from a licensed acupuncturist with experience in digestive disorders.

This Mendelian randomization study analyzed genetic data from 51,665 European-ancestry individuals to examine causal relationships between IBS and cortical brain structure across 34 subregions. Using genome-wide association study (GWAS) data and instrumental variable analysis, researchers identified five significant associations among 68 examined phenotypes. IVW analysis demonstrated IBS was associated with increased surface area in the inferior temporal region (β=22.810 mm², p=0.040) and rostral anterior cingulate (β=11.133 mm², p=0.006). Cortical thickness increased in the isthmus cingulate (β=0.013 mm, p=0.043) and pars opercularis (β=0.010 mm, p=0.010), while decreasing in the rostral anterior cingulate (β=-0.009 mm, p=0.017). Heterogeneity and pleiotropy were assessed through Cochran's Q and MR-Egger intercept tests, with leave-one-out sensitivity analysis confirming robustness. These findings provide genetic evidence for brain-gut axis dysfunction in IBS, supporting the neurobiological basis for psychiatric comorbidities and suggesting that addressing central nervous system involvement may be clinically relevant in IBS management protocols.