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Background: Crohn's disease (CD) is a clinically chronic inflammatory bowel disease, which has been shown to be closely related to the brain-gut axis dysfunction. Although traditionally considered to be a limbic region, the insula has also been commonly identified as an abnormal brain region in previous CD-related studies.Methods: Structural magnetic resonance imaging (MRI) and resting-state functional MRI images were acquired from 45 CD patients in remission and 40 healthy controls (HCs). Three neuroimaging analysis methods including voxel-based morphometry (VBM), structural covariance, and functional connectivity (FC) were applied to investigate structural and functional alterations of the insulae between the CD patients and HCs. Pearson correlation was then used to examine the relationships between neuroimaging findings and clinical symptoms.Results: Compared with the HCs, CD patients exhibited decreased gray matter volume (GMV) in the left dorsal anterior insula (dAI) and bilateral posterior insula (PI). Taking these three areas including the left dAI, right PI, and left PI as regions of interest (ROIs), differences were observed in the structural covariance and FC of the ROI with several regions between the two groups. After controlling for psychological factors, the differences of several regions involved in emotional processing in GMV in the left dAI, the FC of the dAI, and the right PI were not significant. The FC of the parahippocampus/hippocampus with dAI and PI were negatively correlated with the CD activity index (CDAI). Conclusions:We suggest that the insula-centered structural and/or functional changes may be associated with abnormal visceral sensory processing and related emotional responses in CD patients.

Background Ulcerative colitis (UC) and Crohn’s disease (CD) are 2 subtypes of inflammatory bowel disease (IBD). Several studies have reported brain abnormalities in IBD patients. This study aims to identify differences of gray matter volume (GMV) between patients with UC and healthy controls (HCs). Methods Fifty-seven patients with UC and 40 HCs underwent structural magnetic resonance imaging. Voxel-based morphometry method was used to detect GMV differences. Receiver operating characteristic (ROC) curve was applied to investigate reliable biomarkers for identifying patients with UC from HCs. Regression analysis was used to examine relationships between the structure alternations and clinical symptoms. Results Compared with HCs, patients with UC showed decreased GMV in the insula, thalamus, pregenual anterior cingulate cortex, hippocampus/parahippocampus, amygdala, and temporal pole; they showed increased GMV in the putamen, supplementary motor area, periaqueductal gray, hypothalamus, and precentral gyrus. Receiver operating characteristic analysis showed the highest classification power of thalamus. The inclusion of anxiety and depression as covariates eliminated the differences in the right insula, pregenual anterior cingulate cortex, supplementary motor area, and precentral gyrus. Most of the GMV changes were found in active patients with UC, with few changes in patients with UC in remission. We also found significantly negative correlation between UC duration and GMV in several regions. Conclusion The current neuroimaging findings were involved in visceral sensory pathways and were partially associated with the levels of anxiety and depression and clinical stage of patients with UC. This study might provide evidence for possible neuromechanisms of UC.

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