Sex-based associations between neighborhood disadvantage and brain-gut alterations in individuals with irritable bowel syndrome.

Background: Irritable bowel syndrome (IBS) is a stress-sensitive disorder that exhibits sex differences in brain-gut-microbiome interactions. Neighborhood disadvantage is a chronic stressor that may influence brain-gut-microbiome health in patients with IBS, potentially contributing to clinical profiles in a sex-specific manner. This study evaluated sex-based associations between neighborhood disadvantage and clinical characteristics, cortical morphology, and Prevotella relative abundance (a sex-specific microbial marker in IBS) in individuals with IBS compared to healthy controls (HCs).

Methods: Brain magnetic resonance imaging scans were obtained in 182 individuals with IBS (age, 31.0 ± 0.8 years; 128 females) and 161 HCs (age, 32.7 ± 1.0 years; 94 females). Fecal microbiome data was available in 113 IBS participants (80 females) and 127 HCs (74 females). Current neighborhood disadvantage was assessed as the Area Deprivation Index (ADI), with ADI⩾5 defined as high ADI. Group differences in the associations of high ADI with symptoms, Prevotella, and cortical morphology were evaluated using partial least squares.

Results: Diagnosis Differences: High ADI was associated with greater lateral intraparietal surface area in IBS vs HCs. Sex Differences: There were greater negative associations between high ADI and surface area in frontal operculum and thickness in frontopolar and primary somatosensory regions in females vs males. Diagnosis*Sex Differences: There were greater negative associations between high ADI and surface area in superior parietal and sensorimotor regions in IBS females vs males, and greater negative associations between high ADI and surface area and thickness in dorsolateral prefrontal and parietal regions, respectively, in IBS males vs females. High ADI was associated with greater symptom severity in IBS males, greater perceived stress in both IBS and HC females, and Prevotella relative abundance in IBS females (all p's < 0.01).

Conclusions: Neighborhood disadvantage is associated with greater symptom severity in IBS males and both higher perceived stress (exacerbates symptoms) and Prevotella abundance (protective) in IBS females. It generally has a greater negative impact on emotion/pain-related cortical morphology in females vs males. However, there are more prominent somatosensory reductions in IBS females, and prefrontal reductions in IBS males. These findings highlight the interplay between social and biological factors in IBS and underscore the need for targeted, sex-specific interventions.