Regional Gray Matter Density Changes in Brains of Patients With Irritable Bowel Syndrome

Abstract

Background & Aims Several studies have examined structural brain changes associated with chronic pain syndromes, including irritable bowel syndrome (IBS), but study sample sizes have been small and heterogeneous. Methods We used magnetic resonance imaging (MRI)-based techniques, voxel-based morphometry, and cortical thickness analysis, to examine brain anatomical differences in a relatively large, tightly screened sample of IBS patients (n=55); we compared data with that from healthy individuals (controls, n=48). Results IBS was associated with decreased gray matter density (GMD) in widespread areas of the brain, including medial prefrontal and ventrolateral prefrontal cortex, posterior parietal cortex, ventral striatum, and thalamus. Compared with controls, we observed increased GMD in patients with IBS in the pregenual anterior cingulate cortex and the orbitofrontal cortex, as well as trends in the posterior insula/secondary somatosensory cortex, (para)hippocampus, and left dorsolateral prefrontal cortex. In accounting for anxiety and depression, we found that several of the regions involved in affective processing no longer differed between patients with IBS and controls, whereas the differences in prefrontal and posterior parietal cortices remained. The areas of decreased GMD associated with IBS were largely consistent across clinical subgroups, based on predominant bowel habit and pain predominance of symptoms. There were no overall or regional differences in cortical thickness between patients with IBS and controls. Conclusions Changes in density of gray matter among regions involved in cognitive/evaluative functions are specifically observed in patients with IBS, whereas changes in other areas of the brain can be accounted for explained by levels of anxiety and depression.

The Irritable Bowel Syndrome: How Stress Can Affect the Amygdala Activity and the Brain-Gut Axis

“…In agreement, early-life stress induces a decrease of hippocampal volume and functional alterations when measured in adulthood (Nemeroff, et al 2006). Structural changes have also been observed in IBS patients using brain imaging (Blankstein, et al 2010;Seminowicz, et al 2010). Also, circulating glucocorticoids can have contrasting effects in the amygdala and hippocampus, and these two structures can play contrasting roles in the activity of the HPA axis.…”

“…abnormal loci of cerebral activation) of pain was observed in IBS patients (Bonaz, et al 2002;Agostini, et al 2011). In addition, brain structural changes of the HPA axis and limbic structures have been recently reported in IBS patients (Blankstein, et al 2010;Seminowicz, et al 2010).…”

“…An activation of most of the brain structures referenced above, and particularly the amygdala, has been observed in healthy volunteers following rectal pain while an abnormal brain processing of pain was observed in IBS and IBD patients (Baciu, et al 1999;Bonaz, et al 2002;Agostini, et al 2011). In addition, brain structural changes of the HPA axis and limbic structures have been recently reported in IBS patients (Blankstein, et al 2010;Seminowicz, et al 2010). Because psycho-or pharmacotherapy tends to result in normalization of activity of key structures such as the PFC including anterior cingulate cortex, hippocampus, or amygdala, either through a top-down or bottom-up effect (Quide, et al 2012), the determination of psycho-physiological vulnerability in IBS patients should be a flag to consider the psychological needs in the follow-up of such patients in the prevention of relapses of such diseases (Pellissier, et al 2010b).…”

The Increased Level of Depression and Anxiety in Irritable Bowel Syndrome Patients Compared with Healthy Controls: Systematic Review and Meta-analysis

“…[10][11][12][13][15][16][17][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] The baseline characteristics of included studies are shown in Table 1 22,29 Sphere score in 1 study, 24 and the Beck Anxiety Inventory (BAI) in 1 study. 30 …”

“…4 Several recently published studies have mapped IBS's relationship with psychological disorders [10][11][12][13][14][15][16] and compared depression and anxiety levels in IBS-subtypes. 15,17,18 However, the relationship between IBS and psychological disorders (depression or anxiety) was inconsistent, even in a recent meta-analysis entailing eight studies. 19 The heterogeneity of the results was too high, with no further analysis of its cause.…”