New insights into the brain involvement in patients with Crohn's disease: a voxel-based morphometry study

Morphological and regional spontaneous functional aberrations in the brain associated with Crohn's disease: a systematic review and coordinate-based meta-analyses

Crohn's disease is an acknowledged "brain-gut" disorder with unclear physiopathology. This study aims to identify potential neuroimaging biomarkers of Crohn's disease. Gray matter volume, cortical thickness, amplitude of low-frequency fluctuations, and regional homogeneity were selected as indices of interest and subjected to analyses using both activation likelihood estimation and seed-based d mapping with permutation of subject images. In comparison to healthy controls, Crohn's disease patients in remission exhibited decreased gray matter volume in the medial frontal gyrus and concurrently increased regional homogeneity. Furthermore, gray matter volume reduction in the medial superior frontal gyrus and anterior cingulate/paracingulate gyri, decreased regional homogeneity in the median cingulate/paracingulate gyri, superior frontal gyrus, paracentral lobule, and insula were observed. The gray matter changes of medial frontal gyrus were confirmed through both methods: decreased gray matter volume of medial frontal gyrus and medial superior frontal gyrus were identified by activation likelihood estimation and seed-based d mapping with permutation of subject images, respectively. The meta-regression analyses showed a positive correlation between regional homogeneity alterations and patient age in the supplementary motor area and a negative correlation between gray matter volume changes and patients' anxiety scores in the medial superior frontal gyrus. These anomalies may be associated with clinical manifestations including abdominal pain, psychiatric disorders, and possibly reflective of compensatory mechanisms.

The gut-brain axis: Correlation of choroid plexus volume and permeability with inflammatory biomarkers in Crohn's disease

BACKGROUND

The dysregulation of the gut-brain axis in chronic inflammatory bowel diseases can cause neuro-psychological disturbances, but the underlying mechanisms are still not fully understood. The choroid plexus (CP) maintains brain homeostasis and nourishment through the secretion and clearance of cerebrospinal fluid. Recent research has demonstrated the existence of a CP vascular barrier in mice which is modulated during intestinal inflammation. This study investigates possible correlations between CP modifications and inflammatory activity in patients with Crohn's disease (CD).

METHODS

In this prospective study, 17 patients with CD underwent concomitant abdominal and brain 3 T MRI. The volume and permeability of CP were compared with levels of C-reactive protein (CRP), fecal calprotectin (FC), sMARIA and SES-CD scores.

RESULTS

The CP volume was negatively correlated with CRP levels (R = -0.643, p-value = 0.024) and FC (R = -0.571, p-value = 0.050). DCE metrics normalized by CP volume were positively correlated with CRP (K-trans: R = 0.587, p-value = 0.045; Vp: R = 0.706, p-value = 0.010; T1: R = 0.699, p-value = 0.011), and FC (Vp: R = 0.606, p-value = 0.037).

CONCLUSIONS

Inflammatory activity in patients with CD is associated with changes in CP volume and permeability, thus supporting the hypothesis that intestinal inflammation could affect the brain through the modulation of CP vascular barrier also in humans.

Brain imaging derived phenotypes: a biomarker for the onset of inflammatory bowel disease and a potential mediator of mental complications

Background and aims

Inflammatory bowel disease (IBD), mainly categorized into Crohn's disease (CD) and ulcerative colitis (UC), is a chronic relapsing gastrointestinal disorder that significantly impairs patients' quality of life. IBD patients often experience comorbidities such as anxiety and depression, and the underlying mechanisms and treatment strategies remain areas of investigation.

Methods

We conducted a Mendelian randomization(MR) analysis utilizing brain image derived phenotypes (IDP) from the UK Biobank database to investigate the causal relationships between IBD and alterations in brain structural morphology and connectivity of neural tracts. This study aimed to identify biological evidence linking IBD to psychiatric disorders such as anxiety and depression.

Results

Specifically, the volume of grey matter in the Left Frontal Orbital Cortex exhibited a negative association with the onset of Crohn's disease (odds ratio (OR) [95% confidence interval (CI)]: 0.315[0.180~0.551], adjusted P=0.001), while the volume of the superior frontal cortex in the right hemisphere showed a positive correlation with the development of Ulcerative colitis (OR [95% CI]: 2.285[1.793~2.911], adjusted P<0.001), and the volume of lateral occipital cortex in the left hemisphere demonstrated a positive relationship with Crohn's disease onset (OR [95% CI]: 1.709[1.671~1.747], adjusted P<0.001). In the context of reverse causality, the onset of UC or CD has led to alterations in imaging derived phenotypes associated with five disorders (anxiety, depression, schizophrenia, bipolar disorder, pain) and three functions (memory, emotion, language).

Conclusion

Our study has demonstrated a causal relationship between IBD and IDPs. IDPs may serve as potential biomarkers for the progression of IBD and as predictive intermediaries for the development of neurological diseases in IBD patients.

Exploring changes in brain function in IBD patients using SPCCA: a study of simultaneous EEG-fMRI

Research on functional changes in the brain of inflammatory bowel disease (IBD) patients is emerging around the world, which brings new perspectives to medical research. In this paper, the methods of canonical correlation analysis (CCA), kernel canonical correlation analysis (KCCA), and sparsity preserving canonical correlation analysis (SPCCA) were applied to the fusion of simultaneous EEG-fMRI data from 25 IBD patients and 15 healthy individuals. The CCA, KCCA and SPCCA fusion methods were used for data processing to compare the results obtained by the three methods. The results clearly show that there is a significant difference in the activation intensity between IBD and healthy control (HC), not only in the frontal lobe (p < 0.01) and temporal lobe (p < 0.01) regions, but also in the posterior cingulate gyrus (p < 0.01), gyrus rectus (p < 0.01), and amygdala (p < 0.01) regions, which are usually neglected. The mean difference in the SPCCA activation intensity was 60.1. However, the mean difference in activation intensity was only 36.9 and 49.8 by using CCA and KCCA. In addition, the correlation of the relevant components selected during the SPCCA calculation was high, with correlation components of up to 0.955; alternatively, the correlations obtained from CCA and KCCA calculations were only 0.917 and 0.926, respectively. It can be seen that SPCCA is indeed superior to CCA and KCCA in processing high-dimensional multimodal data. This work reveals the process of analyzing the brain activation state in IBD disease, provides a further perspective for the study of brain function, and opens up a new avenue for studying the SPCCA method and the change in the intensity of brain activation in IBD disease.

The role of neurotransmitters in mediating the relationship between brain alterations and depressive symptoms in patients with inflammatory bowel disease

A growing body of evidence from neuroimaging studies suggests that inflammatory bowel disease (IBD) is associated with functional and structural alterations in the central nervous system and that it has a potential link to emotional symptoms, such as anxiety and depression. However, the neurochemical underpinnings of depression symptoms in IBD remain unclear. We hypothesized that changes in cortical gamma-aminobutyric acid (GABA+) and glutamine (Glx) concentrations are related to cortical thickness and resting-state functional connectivity in IBD as compared to healthy controls. To test this, we measured whole-brain cortical thickness and functional connectivity within the medial prefrontal cortex (mPFC), as well as the concentrations of neurotransmitters in the same brain region. We used the edited magnetic resonance spectroscopy (MRS) with the MEGA-PRESS sequence at a 3 T scanner to quantitate the neurotransmitter levels in the mPFC. Subjects with IBD (N = 37) and healthy control subjects (N = 32) were enrolled in the study. Compared with healthy controls, there were significantly decreased GABA+ and Glx concentrations in the mPFC of patients with IBD. The cortical thickness of patients with IBD was thin in two clusters that included the right medial orbitofrontal cortex and the right posterior cingulate cortex. A seed-based functional connectivity analysis indicated that there was higher connectivity of the mPFC with the left precuneus cortex (PC) and the posterior cingulate cortex, and conversely, lower connectivity in the left frontal pole was observed. The functional connectivity between the mPFC and the left PC was negatively correlated with the IBD questionnaire score (r = -0.388, p = 0.018). GABA+ concentrations had a negative correlation with the Hamilton Depression Scale (HAMD) score (r = -0.497, p = 0.002). Glx concentration was negatively correlated with the HAMD score (r = -0.496, p = 0.002) and positively correlated with the Short-Form McGill Pain Questionnaire score (r = 0.330, p = 0.046, uncorrected). There was a significant positive correlation between the ratio of Glx to GABA+ and the HAMD score (r = 0.428, p = 0.008). Mediation analysis revealed that GABA+ significantly mediated the main effect of the relationship between the structural and functional alterations and the severity of depression in patients with IBD. Our study provides initial evidence of neurochemistry that can be used to identify potential mechanisms underlying the modulatory effects of GABA+ on the development of depression in patients with IBD.

Altered voxel-based and surface-based morphometry in inflammatory bowel disease

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is characterized by inflammation of the gastrointestinal tract and is a disorder of the brain-gut axis. Neuroimaging studies of brain function and structure have helped better understand the relationships between the brain, gut, and comorbidity in IBD. Studies of brain structure have primarily employed voxel-based morphometry to measure grey matter volume and surface-based morphometry to measure cortical thickness. Far fewer studies have employed other surface-based morphometry metrics such as gyrification, cortical complexity, and sulcal depth. In this study, brain structure differences between 72 adults with IBD and 90 healthy controls were assessed using all five metrics. Significant differences were found for cortical thickness with the IBD group showing extensive left-lateralized thinning, and for cortical complexity with the IBD group showing greater complexity in the left fusiform and right posterior cingulate. No significant differences were found in grey matter volume, gyrification, or sulcal depth. Within the IBD group, a post hoc analysis identified that disease duration is associated with cortical complexity of the right supramarginal gyrus, albeit with a more lenient threshold applied.

Chronic abdominal pain in inflammatory bowel disease: a practical guide

Pain is common in inflammatory bowel disease (IBD), yet many patients feel their pain is not addressed by healthcare professionals. Listening to a patient's concerns about pain, assessing symptoms and acknowledging the impact these have on daily life remain crucial steps in addressing pain in IBD. While acute pain may be effectively controlled by pain medication, chronic pain is more complex and often pharmacological therapies, particularly opioids, are ineffective. Low-dose tricyclic antidepressants and psychological approaches, including cognitive-behavioural therapy, have shown some promise in offering effective pain management while lifestyle changes such as a trial of low-fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet in those with overlapping irritable bowel syndrome may also reduce pain. Patients benefit from a long-term, trusting relationship with their healthcare professional to allow a holistic approach combining pharmacological, psychological, lifestyle and dietary approaches to chronic pain. We present a practical review to facilitate management of chronic abdominal pain in IBD.

Abdominal Pain in Inflammatory Bowel Disease: An Evidence-Based, Multidisciplinary Review

Abdominal pain is one of the most common and impactful symptoms associated with inflammatory bowel disease (IBD), including both Crohn's disease and ulcerative colitis. A great deal of research has been undertaken over the past several years to improve our understanding and to optimize management of this issue. Unfortunately, there is still significant confusion about the underlying pathophysiology of abdominal pain in these conditions and the evidence underlying treatment options in this context. There is also a relative paucity of comprehensive reviews on this topic, including those that simultaneously evaluate pharmacological and nonpharmacological therapeutic options. In this review, our multidisciplinary team examines evidence for various currently available medical, surgical, and other analgesic options to manage abdominal pain in IBD.

A meta-analysis of structural MRI studies of the brain in systemic lupus erythematosus (SLE)

A comprehensive search of published literature in brain volumetry was conducted in three autoimmune diseases - systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and ulcerative colitis (UC) - with the intention of performing a meta-analysis of published data. Due to the lack of data in RA and UC, the reported meta-analysis was limited to SLE. The MEDLINE database was searched for studies from 1988 to March 2022. A total of 175 papers met the initial inclusion criteria, and 16 were included in a random-effects meta-analysis. The reduction in the number of papers included in the final analysis is primarily due to the lack of overlap in measured and reported brain regions. A significantly lower volume was seen in patients with SLE in the hippocampus, corpus callosum, and total gray matter volume measurements as compared to age- and sex-matched controls. There were not enough studies to perform a meta-analysis for RA and UC; instead, we include a summary of published volumetric studies. The meta-analyses revealed structural brain abnormalities in patients with SLE, suggesting that lower global brain volumes are associated with disease status. This volumetric difference was seen in both the hippocampus and corpus callosum and total gray matter volume measurements. These results indicate both gray and white matter involvements in SLE and suggest there may be both localized and global reductions in brain volume.

Structural imaging studies of patients with chronic pain: an anatomical likelihood estimate meta-analysis

ABSTRACT

Neuroimaging is a powerful tool to investigate potential associations between chronic pain and brain structure. However, the proliferation of studies across diverse chronic pain syndromes and heterogeneous results challenges data integration and interpretation. We conducted a preregistered anatomical likelihood estimate meta-analysis on structural magnetic imaging studies comparing patients with chronic pain and healthy controls. Specifically, we investigated a broad range of measures of brain structure as well as specific alterations in gray matter and cortical thickness. A total of 7849 abstracts of experiments published between January 1, 1990, and April 26, 2021, were identified from 8 databases and evaluated by 2 independent reviewers. Overall, 103 experiments with a total of 5075 participants met the preregistered inclusion criteria. After correction for multiple comparisons using the gold-standard family-wise error correction ( P < 0.05), no significant differences associated with chronic pain were found. However, exploratory analyses using threshold-free cluster enhancement revealed several spatially distributed clusters showing structural alterations in chronic pain. Most of the clusters coincided with regions implicated in nociceptive processing including the amygdala, thalamus, hippocampus, insula, anterior cingulate cortex, and inferior frontal gyrus. Taken together, these results suggest that chronic pain is associated with subtle, spatially distributed alterations of brain structure.

The relationship between Central Nervous System morphometry changes and key symptoms in Crohn’s disease

Alterations in grey matter volume (GMV) and cortical thickness (CT) in Crohn’s disease (CD) patients has been previously documented. However, the findings are inconsistent, and not a true representation of CD burden, as only CD patients in remission have been studied thus far. We investigate alterations in brain morphometry in patients with active CD and those in remission, and study relationships between brain structure and key symptoms of fatigue, abdominal pain, and extraintestinal manifestations (EIM). Magnetic Resonance Imaging brain scans were collected in 89 participants; 34 CD participants with active disease, 13 CD participants in remission and 42 healthy controls (HCs); Voxel based morphometry (VBM) assessed GMV and white matter volume (WMV), and surface-based analysis assessed cortical thickness (CT). We show a significant reduction in global cerebrospinal fluid (CSF) volume in CD participants compared with HCs, as well as, a reduction in regional GMV, WMV and CT in the left precentral gyrus (motor cortex), and an increase in GMV in the frontal brain regions in CD compared with HCs. Atrophy of the supplementary motor area (SMA) was associated with greater fatigue in CD. We also show alterations in brain structure in multiple regions in CD associated with abdominal pain and extraintestinal inflammations (EIMs). These brain structural alterations likely reflect neuroplasticity to a chronic systemic inflammatory response, abdominal pain, EIMs and fatigue. These findings will aid our understanding of the cross-linking between chronic inflammation, brain structural changes and key unexplained CD symptomatology like fatigue.

Depression and anxiety in inflammatory bowel disease: epidemiology, mechanisms and treatment

Inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis, is a chronic, relapsing immune-mediated disease with a varying and sometimes severe disease course. IBD is often diagnosed in early adulthood and can lead to a substantial decline in quality of life. It has been suggested that patients with IBD are at increased risk of depression and anxiety, but it is still unclear to what extent these diseases co-occur and in what sequence they arise. This Review summarizes the literature on the degree of co-occurrence of IBD with depression and anxiety and the temporal relationship between these diseases. We also discuss the effect of psychological stress on the onset and course of IBD. In addition, we outline the possible mechanisms underlying the co-occurrence of IBD and depression and anxiety, which include changes in brain signalling and morphology, increases in peripheral and intracerebral pro-inflammatory cytokines, impairment of the nitric oxide pathway, changes in vagal nerve signalling, gut dysbiosis and genetics. Finally, we examine the possible effects of treatment of depression and anxiety on the risk and course of IBD, the influence of psychological interventions on IBD, and the effects of IBD treatment on psychiatric comorbidity.

Altered mean apparent propagator-based microstructure and the corresponding functional connectivity of the parahippocampus and thalamus in Crohn’s disease

Crohn’s disease (CD) is a chronic and relapsing inflammatory bowel disorder that has been shown to generate neurological impairments, which has the potential to signify disease activity in an underlying neurological manner. The objective of this study was to investigate the abnormalities of brain microstructure and the corresponding functional connectivity (FC) in patients with CD, as well as their associations with disease condition. Twenty-two patients with CD and 22 age-, gender-, and education-matched healthy controls (HCs) were enrolled in this study. All subjects underwent mean apparent propagator (MAP)-MRI and resting-state functional magnetic resonance imaging (MRI) (rs-fMRI) data collection. Each patient was evaluated clinically for the condition and duration of the disease. The MAP metrics were extracted and compared between two groups. Pearson’s correlation analysis was conducted to determine the relationship between disease characteristics and significantly abnormal MAP metrics in the CD group. Regions of interest (ROIs) for ROI-wise FC analysis were selected based on their correlation with MAP metrics. Results showed that multiple brain regions, including the parahippocampus and thalamus, exhibited statistically significant differences in MAP metrics between CD patients and HCs. Additionally, CD patients exhibited decreased FC between the left parahippocampus and bilateral thalamus, as well as the right parahippocampus and bilateral thalamus. The findings of this work provide preliminary evidence that structural abnormalities in the parahippocampal gyrus (PHG) and thalamus, as well as decreased FC between them, may reflect the degree of inflammatory of the disease and serve as brain biomarkers for evaluating CD activity.

Evaluation of Subcortical Structure Volumes in Patients with Non-Specific Digestive Diseases

(1) Background: To evaluate volume of subcortical structures such as hippocampus, globus pallidus, putamen, thalamus, nucleus accumbens, amygdala, caudate in patients with non-specific digestive diseases (functional dyspepsia—FD, irritable bowel syndrome—IBS) and non-specific inflammatory bowel diseases—IBD (colitis ulcerosa and Crohn’s disease) in comparison to healthy control group (CON). (2) Material: The analysis included data obtained from 57 patients (FD-18, IBS-20, IBD-19) and 19 persons in control group. Both groups underwent examination in a 3T scanner (Achieva TX Philips Healthcare). (3) Results: Significant differences between the IBD group and Control group in volume of left thalamus and IBD group vs Control group in volume of right thalamus. (4) Conclusions: The brain-gut axis hypothesis explains connection between biological behavior, emotions and cognitive functions in patients with gastrointestinal disease. We found that there is a difference between volume of thalamus in IBD patients in comparison to both IBS and control group and it occurred to be smaller. Excess inflammation can be linked with psychological disorders like depressive symptoms, sleep difficulties and/or fatigue. Therefore, there is a need for using treatment both for depressive symptoms and IBD to reduce the causes and effects of inflammation.

Impact of the COVID‐19 pandemic on inflammatory bowel disease: The role of emotional stress and social isolation

Inflammatory bowel disease (IBD) is a chronic health condition exacerbated by negative emotional stress experiences. In the current study, we examined whether the outbreak of the COVID-19 pandemic coincided with an increase in stress experiences and accordingly an aggravation of disease activity in IBD patients. Sixty-three IBD patients (30 Crohn's disease or CD, 33 ulcerative colitis) completed an online survey during the COVID-19-related lockdown, assessing clinical disease activity, disease-related quality of life, presence of functional gastrointestinal symptoms, social isolation and stress experiences. Scores were then compared to pre-lockdown baseline screening. The pandemic yielded a significant baseline-to-lockdown increase in emotional stress and social isolation. Stress increments, particularly those occasioned by interpersonal tension and excessive interpersonal proximity, were associated with a worsening of functional gastrointestinal symptoms. Exacerbations of loneliness coincided with an escalation of CD activity, functional gastrointestinal symptoms and a decline in subjective health. Lastly, COVID-19 anxiety was significantly related to CD symptom severity and social dysfunction. The findings show that shifts in IBD expression are closely linked to changes in emotional stress experiences and interpersonal relatedness. As such, they contribute to a better understanding of inter-individual differences in IBD progression and provide leads for therapeutic interventions.

Altered Intra- and Inter-Network Functional Connectivity in Patients With Crohn’s Disease: An Independent Component Analysis-Based Resting-State Functional Magnetic Resonance Imaging Study

Background

Many studies have reported changes in the structure and function of several brain areas in patients with Crohn’s disease (CD). However, little is known about whether the possible functional connectivity of resting-state networks (RSNs) is altered in CD patients.

Purpose

Aim to investigate the intra- and inter-network alterations between related RSNs in patients with CD and the potential relationships between altered neuroimaging and CD clinical indices.

Materials and Methods

In this study, 20 CD patients and 22 age- and sex-matched healthy controls were included. All participants underwent functional magnetic resonance imaging examination. We used independent component analysis (ICA) to explore the changes in RSNs and evaluated functional connectivity between different RSNs using functional network connectivity (FNC) analysis, and Pearson correlation analysis was performed between altered intra- and inter-network functional connectivity and CD clinical index.

Results

Six CD-related RSNs were identified via ICA, namely the high visual, prime visual, language, dorsal default mode, posterior insula, and precuneus networks. Compared to healthy controls, patients with CD showed significant changes in prime visual and language networks. Additionally, the functional connectivity (FC) values of the left calcarine within the prime visual network were negatively correlated with CD duration. The inter-alterations showed that a significantly increased FNC existed between the language and dorsal default mode networks.

Conclusion

The results showed CD-related changes in brain functional networks. This evidence provides more insights into the pathophysiological mechanisms of brain plasticity in CD.

Functional Brain Changes Due to Chronic Abdominal Pain in Inflammatory Bowel Disease: A Case-Control Magnetic Resonance Imaging Study

INTRODUCTION

Various chronic pain conditions go along with functional and structural brain changes. This study aimed to investigate functional and structural brain changes by magnetic resonance imaging (MRI) in inflammatory bowel disease (IBD) patients with chronic abdominal pain.

METHODS

Sixty-four subjects were included in the final analysis (32 IBD patients with chronic abdominal pain; 32 age-matched and sex-matched controls). All patients suffered from chronic abdominal pain, defined as a score of ≥3/10 on the visual analog scale for at least 3 months in the past 6 months. Besides structural MRI, resting state functional MRI was used to compare functional connectivity of 10 networks between groups.

RESULTS

Patients with IBD showed no structural brain alterations but a significantly increased resting state functional connectivity of the secondary somatosensory cortex within the salience network.

DISCUSSION

Because the secondary somatosensory cortex saves sensory stimuli and compares novel information with latter experiences, these functions may be maladaptive in IBD patients with abdominal pain.

Altered Brain Structure in Chronic Visceral Pain: Specific Differences in Gray Matter Volume and Associations With Visceral Symptoms and Chronic Stress

Structural brain alterations in chronic pain conditions remain incompletely understood, especially in chronic visceral pain. Patients with chronic-inflammatory or functional bowel disorders experience recurring abdominal pain in concert with other gastrointestinal symptoms, such as altered bowel habits, which are often exacerbated by stress. Despite growing interest in the gut-brain axis and its underlying neural mechanisms in health and disease, abnormal brain morphology and possible associations with visceral symptom severity and chronic stress remain unclear. We accomplished parallelized whole-brain voxel-based morphometry analyses in two patient cohorts with chronic visceral pain, i.e., ulcerative colitis in remission and irritable bowel syndrome, and healthy individuals. In addition to analyzing changes in gray matter volume (GMV) in each patient cohort vs. age-matched healthy controls using analysis of covariance (ANCOVA), multiple regression analyses were conducted to assess correlations between GMV and symptom severity and chronic stress, respectively. ANCOVA revealed reduced GMV in frontal cortex and anterior insula in ulcerative colitis compared to healthy controls, suggesting alterations in the central autonomic and salience networks, which could however not be confirmed in supplemental analyses which rigorously accounted for group differences in the distribution of sex. In irritable bowel syndrome, more widespread differences from healthy controls were observed, comprising both decreased and increased GMV within the sensorimotor, central executive and default mode networks. Associations between visceral symptoms and GMV within frontal regions were altered in both patient groups, supporting a role of the central executive network across visceral pain conditions. Correlations with chronic stress, on the other hand, were only found for irritable bowel syndrome, encompassing numerous brain regions and networks. Together, these findings complement and expand existing brain imaging evidence in chronic visceral pain, supporting partly distinct alterations in brain morphology in patients with chronic-inflammatory and functional bowel disorders despite considerable overlap in symptoms and comorbidities. First evidence pointing to correlations with chronic stress in irritable bowel syndrome inspires future translational studies to elucidate the mechanisms underlying the interconnections of stress, visceral pain and neural mechanisms of the gut-brain axis.

Review article: The aetiology of fatigue in inflammatory bowel disease and potential therapeutic management strategies

BACKGROUND

Fatigue is the inability to achieve or maintain an expected work output resulting from central or peripheral mechanisms. The prevalence of inflammatory bowel disease (IBD) fatigue can reach 86% in active disease, persisting in 50%-52% of patients with mild to inactive disease. Fatigue is the commonest reason for work absence in IBD, and patients often report fatigue burden to be greater than that of primary disease symptoms. Relatively few evidence-based treatment options exist, and the aetiology is poorly understood.

AIM

To review the available data and suggest a possible aetiology of IBD fatigue and to consider the efficacy of existing management strategies and highlight potential future interventions.

METHODS

We reviewed fatigue-related literature in IBD using PubMed database.

RESULTS

Disease related factors such as inflammation and pharmacological treatments negatively impact skeletal muscle and brain physiology, likely contributing to fatigue symptoms. Secondary factors such as malnutrition, anaemia, sleep disturbance and psychological comorbidity are potential determinants. Immune profile, faecal microbiota composition and physical fitness differ significantly between fatigued and non-fatigued patients, suggesting these may be aetiological factors. Solution-focused therapy, high-dosage thiamine supplementation and biological therapy may reduce fatigue perception in IBD. The effect of physical activity interventions is inconclusive.

CONCLUSIONS

A multimodal approach is likely required to treat IBD fatigue. Established reversible factors like anaemia, micronutrient deficiencies and active disease should initially be resolved. Psychosocial intervention shows potential efficacy in reducing fatigue perception in quiescent disease. Restoring physical deconditioning by exercise training intervention may further improve fatigue burden.

Brain functional changes in patients with Crohn's disease: A resting-state fMRI study

BACKGROUND

Crohn's disease (CD) is a chronic recurrent intestinal inflammatory disease, often accompanied by poor adaptation and excessive stress response. However, the potential neurological mechanisms of these symptoms have not yet been studied in-depth.

OBJECTIVE

To investigate alterations in brain activity in patients with Crohn's disease and study the relationship between altered regions and clinical indices.

METHODS

A total of 15 CD patients and 26 matched healthy controls were recruited. All participants underwent fMRI scans. The amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) assessed differences in spontaneous regional brain activity. Differences between the groups were selected as seeds for functional connectivity (FC) analyses. Correlations between disease duration and ALFF/ReHo/FC values in abnormal regions were analyzed.

RESULTS

Patients with CD had significantly higher ALFF values in the left superior frontal gyrus, anterior cingulate cortex, and supplementary motor area, and lower values in the left hippocampus. They also had higher ReHo values in the left anterior cingulate cortex, supplementary motor area, putamen, and the bilateral superior frontal gyri. FC strength in the left precentral and middle temporal gyri was found to be increased when the left superior frontal gyrus was used as the seed point. FC strength was also observed to be increased in the left postcentral, middle frontal gyri, inferior frontal orbital cortex, and right rolandic operculum when the left anterior cingulate cortex was used as the seed point.

CONCLUSION

CD demonstrated abnormal neural activity and FC in various regions primarily associated with emotional, pain and cognitive-related functions, which provides more information to further understand the neural mechanisms of the disease.

Higher Levels of Psychological Burden and Alterations in Personality Functioning in Crohn's Disease and Ulcerative Colitis

Aims: Is there evidence for increased psychological distress and alterations in personality functioning in patients with Crohn’s disease (CD) and ulcerative colitis (UC) compared to healthy controls (HCs)?

Background: In patients with CD and UC, perceived stress is closely associated with changes in disease activity. The stress response is influenced by psychological burden and personality functioning, but only little is known about these factors in inflammatory bowel diseases (IBD).

Study: A total of 62 patients with an endoscopic ensured CD/UC without remission (n = 31 per group) and 31 HC were included. Patients with an active CD/UC and HC were individually matched (n = 93, 31 per group) for age, sex, education, and disease activity. Depression and anxiety were assessed to evaluate the effect of psychological burden (Patient Health Questionnaire-9/PHQ-9, Generalized Anxiety Disorder-7/GAD-7). Personality functioning was measured by validated questionnaires for psychodynamic structural characteristics, mentalization, and attachment (Operationalized Psychodynamic Diagnosis-Structure Questionnaire/OPD-SQ, Mentalization Questionnaire/MZQ, and Experiences in Close Relationships scale/ECR-RD 12).

Results: Levels of depression and anxiety were higher in CD/UC patients than in HC with large effect sizes. Comparing personality functioning in CD/UC with HC, psychodynamic structural characteristics differed between CD/UC and HC with medium effect sizes, with structural differences occurring primarily in the domain of self-perception and regulation. Only minor differences were found regarding mentalization and attachment. CD and UC differed only with small effect sizes.

Conclusion: Our data show that compared to HC, patients with CD/UC are characterized by a higher level of psychological burden and structural alterations in the domain of self.

Exploring joint patterns of brain structure and function in inflammatory bowel diseases using multimodal data fusion

BACKGROUND

A growing number of neuroimaging studies suggest distinct neural changes in inflammatory bowel diseases (IBDs). Whether such changes may show similar spatial patterns across distinct neural features within and between specific IBD is unclear. To address this question, we used multivariate multimodal data fusion analysis to investigate structure/function modulation in remitted patients with Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

Patients with IBD (n = 46; n = 31 with CD, n = 15 with UC) in stable remission and 17 healthy controls (HC) underwent structural magnetic resonance imaging (sMRI) and resting-state functional magnetic resonance imaging (rs-fMRI) as well as cognitive testing. Anxiety, depression, and fatigue were assessed using self-rating questionnaires. sMRI data were analyzed via voxel-based morphometry (VBM) and rs-fMRI data via amplitude of low-frequency fluctuations (ALFFs) and regional homogeneity (ReHo). Detection of cross-information between VBM, ALFF, and ReHo was conducted by means of a joint independent component analysis (jICA), followed by group-inference statistics.

KEY RESULTS

Joint independent component analysis detected structural alterations in middle frontal and temporal regions (VBM), and functional changes in the superior frontal gyrus (ReHo) and the medial as well as inferior frontal, inferior temporal, rectal, and subcallosal gyrus (ALFF). One joint component of extracted features of the three modalities differed significantly between IBD patients and controls (p = 0.03), and most distinctly between HC and patients with UC.

CONCLUSIONS AND INFERENCES

Using a multivariate data fusion technique, this study provides further evidence to brain alterations in IBD. The data suggest distinct neural differences between CD and UC, particularly in frontotemporal regions.

Structural and functional changes in the brain of patients with Crohn's disease: an activation likelihood estimation meta-analysis

Multiple reports for brain functional and structural alterations in patients with Crohn's disease (CD) were published. The current study aimed to meta-analyze the existing neuroimaging data and hence produce a brain map revealing areas with functional and structural differences between patients with CD and healthy controls. Original studies published until 2019 were identified from Scopus, Web of Science and PubMed databases, and included into the analysis if they reported relevant results from task-related or resting state functional magnetic resonance imaging (fMRI or rsfMRI) or voxel-based morphometry (VBM), in the form of standardized brain coordinates based on whole-brain analysis. The brain coordinates and sample size of significant results were extracted from eligible studies to be meta-analyzed with the activation likelihood estimation method using the GingerALE software. Sixteen original studies comprised of a total of 865 participants fulfilled the inclusion criteria. Compared to healthy controls, patients with CD had reduced resting state brain connectivity in the paracentral lobule and cingulate gyrus as well as reduced grey matter volume in the medial frontal gyrus. No significant results were found vice versa. These neural correlates allow a better understanding on the effects of CD on the pain expectation, emotion, and quality of life of patients and potentially serve as useful biomarkers for evaluating treatment efficacy.

Herbal Medicine and Acupuncture Combined Treatment Attenuates Colitis in Rats

This study aimed to verify the efficacy of a combined treatment of Jakyakgamcho-tang (JGT) and acupuncture (CV12, ST25, CV4) on colitis induced by dextrane sulfate sodium (DSS). Changes in immuno-mediated factors and metabolites were investigated. Colitis symptoms such as body weight loss and elevated disease activity index were alleviated by the combined treatment. Moreover, treatment with JGT and acupuncture restored the disturbed architecture of colon by suppressing inflammatory cytokine levels of IFN-[Formula: see text] ([Formula: see text] < 0.05), IL-5 ([Formula: see text] < 0.05), and IL-13 ([Formula: see text] < 0.0001) compared with the DSS group. Analysis of metabolic profiles of serum revealed that treatment groups were clearly separated from the DSS group, suggesting that JGT and acupuncture treatment altered serum metabolites. Furthermore, treatments caused opposite metabolite patterns for dimethylbenzimidazole, 1,5-anhydro-D-glucitol, proline, phosphate, glycolic acid, aspartic acid, tryptophan, phthalic acid, ornithine, and glutamic acid compared with the DSS group. The combined treatment group induced more effective metabolite patterns than the JGT group, implying that acupuncture treatment can restore metabolic changes caused by DSS induction. These results indicate that the simultaneous treatment of JGT administration and acupuncture procedure provides better management of the immune function and inflammatory expression of colitis than a single treatment. It is assumed that intestinal microbial control can be achieved by acupuncture stimulation as well as by taking herbal medicine.

Visceral hypersensitivity is together with psychological distress and female gender associated with severity of IBS-like symptoms in quiescent ulcerative colitis

BACKGROUND

A subset of ulcerative colitis (UC) patients in remission demonstrate IBS-like symptoms. Visceral hypersensitivity is a key pathophysiological mechanism in IBS, but its relevance to IBS-like symptoms in inactive UC remains unclear.

METHODS

UC patients in remission (UCR) were screened for IBS-like symptoms. Rectal sensitivity was assessed with rectal balloon distensions, with determination of sensory thresholds and unpleasantness/pain intensity ratings. Patients completed questionnaires evaluating gastrointestinal (GI) and psychological symptoms. Age- and gender-matched IBS subjects and healthy controls (HC) also underwent a rectal sensitivity test.

KEY RESULTS

We included 36 UCR patients (18 with IBS-like symptoms (UCR + IBS) and 18 without (UCR - IBS)), 36 IBS subjects, and 14 HC. UCR and IBS patients were more sensitive to rectal balloon distensions than HC, but no differences between UCR and IBS patients were observed. UCR + IBS patients had lower sensory thresholds and higher unpleasantness ratings than UCR - IBS. In UCR patients, the overall GI symptom severity, pain, and bloating, but not diarrhea, constipation or satiety, were associated with rectal sensitivity. In multivariate analyses, rectal sensitivity, psychological distress, and female gender were identified as factors independently associated with GI symptom severity. 61% of UCR patients demonstrated rectal hypersensitivity, and these patients more commonly reported at least mild bloating and pain, and overall GI symptoms, compared to those with normal rectal sensitivity.

CONCLUSION & INFERENCES

Visceral hypersensitivity was associated with IBS-like symptoms, in particular pain and bloating, in inactive UC. Together with psychological factors and female gender, visceral hypersensitivity seems to be involved in GI symptom generation in quiescent UC.

Changes in the anterior cingulate cortex in Crohn's disease: A neuroimaging perspective

INTRODUCTION

Evidence suggests that Crohn's disease (CD) pathophysiology goes beyond the gastrointestinal tract and is also strongly associated with the brain. In particular, the anterior cingulate cortex (ACC), which plays an integral role in the first brain as part of the default mode network (DMN) and pain matrix, shows abnormalities using multiple neuroimaging modalities. This review summarizes nine related studies that investigated changes in the ACC using structural magnetic resonance imaging, resting-state functional magnetic resonance imaging, and magnetic resonance spectroscopy.

METHODS

An extensive PubMed literature search was conducted from 1980 to August 2020. In a review of the articles identified, particular attention was paid to analysis methods, technical protocol characteristics, and specific changes in the ACC.

RESULTS

In terms of morphology, a decrease in gray matter volume and cortical thickness was observed along with an increase in local gyrification index. In terms of function, functional connectivity (FC) within the DMN was increased. FC between the ACC and the amygdala was decreased. Higher amplitudes of low-frequency fluctuation and graph theory results, including connectivity strength, clustering coefficient, and local efficiency, were detected. In terms of neurotransmitter changes, the concentrations of glutamate increased along with a decrease in gamma-aminobutyric acid, providing a rational explanation for abdominal pain. These changes may be attributed to stress, pain, and negative emotions, as well as changes in gut microbiota.

CONCLUSIONS

For patients with CD, the ACC demonstrates structural, functional, and metabolic changes. In terms of clinical findings, the ACC plays an important role in the onset of depression/anxiety and abdominal pain. Therefore, successful modulation of this pathway may guide treatment.

Functional disruption of cortical cingulate activity attenuates visceral hypersensitivity and anxiety induced by acute experimental colitis

Visceral pain is a highly complex experience and is the most common pathological feature in patients suffering from inflammatory gastrointestinal disorders. Whilst it is increasingly recognized that aberrant neural processing within the gut-brain axis plays a key role in development of neurological symptoms, the underlying mechanisms remain largely unknown. Here, we investigated the cortical activation patterns and effects of non-invasive chemogenetic suppression of cortical activity on visceral hypersensitivity and anxiety-related phenotypes in a well-characterized mouse model of acute colitis induced by dextran sulfate sodium (DSS). We found that within the widespread cortical network, the mid-cingulate cortex (MCC) was consistently highly activated in response to innocuous and noxious mechanical stimulation of the colon. Furthermore, during acute experimental colitis, impairing the activity of the MCC successfully alleviated visceral hypersensitivity, anxiety-like behaviors and visceromotor responses to colorectal distensions (CRDs) via downregulating the excitability of the posterior insula (PI), somatosensory and the rostral anterior cingulate cortices (rACC), but not the prefrontal or anterior insula cortices. These results provide a mechanistic insight into the central cortical circuits underlying painful visceral manifestations and implicate MCC plasticity as a putative target in cingulate-mediated therapies for bowel disorders.

MRI-based brain structural changes following radiotherapy of Nasopharyngeal Carcinoma: A systematic review

PURPOSE

Nasopharyngeal carcinoma (NPC) radiotherapy (RT) irradiates parts of the brain which may cause cerebral tissue changes. This study aimed to systematically review the brain microstructure changes using MRI-based measures, diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI) and voxel-based morphometry (VBM) and the impact of dose and latency following RT.

METHODS

PubMed and Scopus databases were searched based on PRISMA guideline to determine studies focusing on changes following NPC RT.

RESULTS

Eleven studies fulfilled the inclusion criteria. Microstructural changes occur most consistently in the temporal region. The changes were correlated with latency in seven studies; fractional anisotropy (FA) and gray matter (GM) volume remained low even after a longer period following RT and areas beyond irradiation site with reduced FA and GM measures. For dosage, only one study showed correlation, thus requiring further investigations.

CONCLUSION

DTI, DKI and VBM may be used as a surveillance tool in detecting brain microstructural changes of NPC patients which correlates to latency and brain areas following RT.

Cognitive Impairment in Adult Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

BACKGROUND

People living with inflammatory bowel disease (IBD) are exposed to multiple risk factors for cognitive impairment and frequently report cognitive difficulties. However, the presence of cognitive impairment in IBD has not been systematically reviewed.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we performed a systematic multidatabase search for cross-sectional and longitudinal studies comparing adults with IBD versus healthy controls for domain-specific cognitive function or scores on multidomain cognitive screening tools. For any domain reported by 3 or more studies, we conducted random-effects meta-analysis to calculate the standardized mean difference between groups; lower scores reflected poorer performance. Between-study heterogeneity was assessed using the I² statistic and study quality assessed using an IBD-modified Newcastle-Ottawa scale.

RESULTS

Of 8302 articles screened, 12 studies (n = 687) were included in the qualitative synthesis and 11 in meta-analyses. All studies were cross-sectional. Studies generally excluded people with active IBD and older adults. Despite no significant differences on multidomain screening tools such as the Mini Mental State Examination (-0.27 [95% confidence interval -0.68, 0.08], P = 0.14), people with IBD showed significant deficits compared with healthy controls in attention (standardized mean difference -0.36 [-0.60, -0.12], P = 0.003, I² = 0%), executive function (standardized mean difference -0.45 [-0.77, -0.13, P = 0.005, I² = 42.5%), and specifically in working memory (standardized mean difference -0.58 [-0.85, -0.30], P < 0.001, I² = 0%). Deficits in learning and recall were nonsignificant (P = 0.089) and other domains insufficient for meta-analysis.

CONCLUSIONS

People with IBD show deficits in attention and executive function, particularly in working memory, suggesting that cognitive impairment is a potential extraintestinal manifestation of IBD.

Gut Inflammation Induced by Dextran Sulfate Sodium Exacerbates Amyloid-β Plaque Deposition in the AppNL-G-F Mouse Model of Alzheimer's Disease

BACKGROUND

Although it is known that the brain communicates with the gastrointestinal (GI) tract via the well-established gut-brain axis, the influence exerted by chronic intestinal inflammation on brain changes in Alzheimer's disease (AD) is not fully understood. We hypothesized that increased gut inflammation would alter brain pathology of a mouse model of AD.

OBJECTIVE

Determine whether colitis exacerbates AD-related brain changes.

METHODS

To test this idea, 2% dextran sulfate sodium (DSS) was dissolved in the drinking water and fed ad libitum to male C57BL/6 wild type and AppNL-G-F mice at 6-10 months of age for two cycles of three days each. DSS is a negatively charged sulfated polysaccharide which results in bloody diarrhea and weight loss, changes similar to human inflammatory bowel disease (IBD).

RESULTS

Both wild type and AppNL-G-F mice developed an IBD-like condition. Brain histologic and biochemical assessments demonstrated increased insoluble Aβ1-40/42 levels along with the decreased microglial CD68 immunoreactivity in DSS treated AppNL-G-F mice compared to vehicle treated AppNL-G-F mice.

CONCLUSION

These data demonstrate that intestinal dysfunction is capable of altering plaque deposition and glial immunoreactivity in the brain. This study increases our knowledge of the impact of peripheral inflammation on Aβ deposition via an IBD-like model system.

Supraspinal Mechanisms of Intestinal Hypersensitivity

Gut inflammation or injury causes intestinal hypersensitivity (IHS) and hyperalgesia, which can persist after the initiating pathology resolves, are often referred to somatic regions and exacerbated by psychological stress, anxiety or depression, suggesting the involvement of both the spinal cord and the brain. The supraspinal mechanisms of IHS remain to be fully elucidated, however, over the last decades the series of intestinal pathology-associated neuroplastic changes in the brain has been revealed, being potentially responsible for the phenomenon. This paper reviews current clinical and experimental data, including the authors' own findings, on these functional, structural, and neurochemical/molecular changes within cortical, subcortical and brainstem regions processing and modulating sensory signals from the gut. As concluded in the review, IHS can develop and maintain due to the bowel inflammation/injury-induced persistent hyperexcitability of viscerosensory brainstem and thalamic nuclei and sensitization of hypothalamic, amygdala, hippocampal, anterior insular, and anterior cingulate cortical areas implicated in the neuroendocrine, emotional and cognitive modulation of visceral sensation and pain. An additional contribution may come from the pathology-triggered dysfunction of the brainstem structures inhibiting nociception. The mechanism underlying IHS-associated regional hyperexcitability is enhanced NMDA-, AMPA- and group I metabotropic receptor-mediated glutamatergic neurotransmission in association with altered neuropeptide Y, corticotropin-releasing factor, and cannabinoid 1 receptor signaling. These alterations are at least partially mediated by brain microglia and local production of cytokines, especially tumor necrosis factor α. Studying the IHS-related brain neuroplasticity in greater depth may enable the development of new therapeutic approaches against chronic abdominal pain in inflammatory bowel disease.

Neuroimmunogastroenterology: At the Interface of Neuroimmunology and Gastroenterology

The central nervous system (CNS) is an important regulator of the gastrointestinal tract, and CNS dysfunction can result in significant and disabling gastrointestinal symptom manifestation. For patients with neuroimmunologic and neuroinflammatory conditions, the recognition of gastrointestinal symptoms is under-appreciated, yet the gastrointestinal manifestations have a dramatic impact on quality of life. The current treatment strategies, often employed independently by the neurologist and gastroenterologist, raise the question of whether such patients are being treated optimally when siloed in one specialty. Neuroimmunogastroenterology lies at the borderlands of medical specialties, and there are few resources to guide neurologists in this area. Here, we provide an overview highlighting the potential mechanisms of crosstalk between immune-mediated neurological disorders and gastrointestinal dysfunction.

The effects of gastrointestinal symptoms on structural grey matter volume in youth

Previous neuroimaging studies have examined the association between changes in brain structure and gastrointestinal symptoms (GIS), seen in disorders such as Irritable Bowel Syndrome and Irritable Bowel Disease. Studies in adults have found changes in white and grey matter volume (GMV) in patients with various gastrointestinal disorders. However, it is unclear whether GIS-related structural changes in the brain are limited to adults or could be present throughout the lifespan. Given that gastrointestinal disorders are typically diagnosed between 4 and 18 years old, we investigated GIS-induced morphological changes in pre-adolescents (8-10), adolescents (12-16 years) and young adults (17-21 years). Using a voxel-based morphometry (VBM) analysis, we compared regional grey matter volume (GMV) between participants with GIS and controls, using structural brain images from the Philadelphia Neurodevelopmental Cohort (PNC) database. A total of 211 participants (107 participants with GISs and 104 control participants) who had undergone structural magnetic resonance imaging were analysed. VBM analysis was used to objectively analyse GMV across the whole brain and compare between participants with GIS and controls. Participants experiencing GIS showed smaller GMV in regions within the limbic system/basal ganglia (bilateral caudate, bilateral ventral hippocampus, bilateral amygdala and bilateral superior orbital frontal cortex), and larger GMV in regions within the pain-matrix (thalamus, bilateral putamen, right mid-frontal gyrus) compared to controls. These differences were most prominent in the adolescent and young adult groups compared to pre-adolescents. In conclusion, the structural differences found in participants with GIS support the need for further research into the neurophysiological impact of these symptoms.

Impaired cognitive function in Crohn's disease: Relationship to disease activity

Background & aims

Impaired attention and response inhibition have been reported in patients with Crohn’s disease (CD) in clinical remission. Prospective studies are needed to determine whether this is a stable feature of CD and whether a similar impairment is evident in ulcerative colitis (UC). Thus, our aims were to examine whether patients with CD and UC exhibited a persistent impairment in attentional performance, and if this impairment was related to key biological indices of relevance to cognition.

Methods

A prospective observational study was conducted on fifteen patients with CD and 7 with UC in clinical remission recruited from a specialty clinic and 30 healthy matched control participants. A neuropsychological assessment was carried out at baseline (visit 1) and at a 6 month follow-up (visit 2). Plasma proinflammatory cytokines, the plasma kynurenine:tryptophan (Kyn:Trp) ratio and the salivary cortisol awakening response (CAR) were also determined at each visit.

Results

Across visits, patients with CD exhibited impaired attentional performance (p ​= 0.023). Plasma IL-6 (P ​= ​0.001) and the Kyn:Trp ratio (P ​= ​0.03) were consistently elevated and the CAR significantly blunted (P ​< ​0.05) in patients with CD. No significant relationships were identified between any biochemical parameter and altered cognitive performance.

Conclusions

Impaired cognitive function is a stable feature of patients with CD. These data suggest that even where remission has been achieved, the functional impact of an organic gastrointestinal disorder on cognition is still evident. However, it is unclear at present if physiological changes due to disease activity play a role in cognitive impairment in CD.

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Crohn’s disease (CD) patients previously associated with impaired cognition.

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CD patients consistently exhibited impaired attentional performance at multiple visits.

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Functional impact of organic gastrointestinal disorder on cognition still evident in remission.

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Increased IL-6, kynurenine pathway activation and blunted cortisol awakening response in CD.

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Biochemical parameters not associated with altered cognitive performance.

Disease course, stress, attachment, and mentalization in patients with inflammatory bowel disease

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, are chronic intestinal disorders that requires lifelong treatments. IBD are associated with perceived stress, poor quality of life, and psychopathological disorders. Previous studies have documented that psychological distress and depression are risk factors for IBD. On the other hand, IBD itself might be a source of psychological stress. IBD negatively affect individuals' daily social interactions and close interpersonal relationships. Despite IBD's detrimental effects on quality of life, patients' adherence to medicaments remains low, increasing the risk of relapses and the subsequent worsening of the clinical condition. Drawing on attachment and mentalization theories, we aim to contribute to understanding of the mechanisms involved in the poor quality of social relationships and the tendency for medication non-adherence in patients with IBD. We hypothesize a bidirectional link between IBD and attachment style and related mentalization abilities, where an individual's attachment style refers to a complex and characteristic pattern of relating to self and others and mentalization refers to the process of inferring one's own and others' mental and physical states. This hypothesized link between IBD and insecure attachment style, mediated by reduced mentalizing abilities, may be a risk factor for developing both IBD-related psychological disorders and reduced medication adherence, which could then lead to worsening disease management and prognoses for the disease course. The medication nonadherence is here considered as both an outcome and a risk factor of this vicious circle. We share the view that preventing the worsening of the IBD condition and promoting patients' medication adherence would be possible by considering the circular relationship between IBD, attachment, and mentalization and by promoting reflective functioning in patients with IBD, from the onset of the disease.

Brain Resting-State Network Alterations Associated With Crohn's Disease

Inflammatory bowel disease (IBD) is a chronic disease that is associated with aspects of brain anatomy and activity. In this preliminary MRI study, we investigated differences in brain structure and in functional connectivity (FC) of brain regions in 35 participants with Crohn's disease (CD) and 21 healthy controls (HC). Voxel-based morphometry (VBM) analysis was performed to contrast CD and HC structural images. Region of interest (ROI) analyses were run to assess FC for resting-state network nodes. Independent component analysis (ICA) identified whole brain differences in FC associated with resting-state networks. Though no structural differences were found, ROI analyses showed increased FC between the frontoparietal (FP) network and salience network (SN), and decreased FC between nodes of the default mode network (DMN). ICA results revealed changes involving cerebellar (CER), visual (VIS), and SN components. Differences in FC associated with sex were observed for both ROI analysis and ICA. Taken together, these changes are consistent with an influence of CD on the brain and serve to direct future research hypotheses.

Persistent central inflammation and region specific cellular activation accompany depression- and anxiety-like behaviours during the resolution phase of experimental colitis

Depression and anxiety-related psychological symptoms are increasingly recognised as important co-morbidities in patients with inflammatory bowel disease (IBD). Dextran sulfate sodium (DSS) -induced colitis is an animal model of IBD in which afferent activation of the gut-brain axis can be assessed and explored as a source of behavioural change. Exposure of adult male Wistar rats to DSS (5%) in drinking water induced distal colitis. In parallel to local inflammatory responses in the gut wall, increased expression of IL-6 and iNOS was found in the cerebral cortex and an increase in ventricular volume. Immunoreactivity of immediate early gene FosB/ΔFosB activation was measured as an index of cellular activation and was increased in the nucleus accumbens and dorsal raphe nucleus in acutely colitic animals. Following resolution of the acute colitic response, sustained anhedonia in the saccharin preference test, immobility in the forced swim test, reduced burying behaviour in the marble burying test, and mild signs of anxiety in the elevated plus maze and light/dark box were observed. Central increases in iNOS expression persisted during the recovery phase and mapped to reactive microglia, particularly those found in the parenchyma surrounding circumventricular regions. Evidence of associated nitration was also found. Sustained increases in ventricular volume and reduced T2 magnetic resonance relaxometry time in cortical regions were observed during the recovery period. FosB/ΔFosB activation was evident in the dorsal raphe during recovery. Persistent central inflammation and cellular activation may underpin the emergence of symptoms of depression and anxiety in experimental colitis.

Aberrant brain structural large-scale connectome in Crohn's disease

BACKGROUND

Disturbed brain-gut interactions and a bidirectional relationship between inflammation and psychiatric symptoms such as anxiety and depression are being discussed in patients with inflammatory bowel diseases (IBD). Alterations of brain structure and function in IBD have been reported with heterogeneous results. Whether these changes reflect independent localized deficits or rather a systematic disruption in the anatomical organization of large-scale brain networks remains unclear. The present study investigated the gray matter structural connectome in patients with Crohn's disease (CD).

METHODS

Sixty participants (30 with quiescent CD and 30 matched healthy controls [HC]) underwent high-resolution brain MRI at 3 Tesla. Well-established graph theoretical metrics were analyzed at the global and regional network level and compared between groups.

KEY RESULTS

The networks in both groups followed a small-world organization, that is, an architecture that is simultaneously highly segregated and integrated. However, transitivity, a measure of global network segregation, was significantly reduced in patients (P = 0.003). Regionally, patients showed a reduction of nodal betweenness centrality in the right insula and cuneus and the left superior frontal cortex and reduced nodal degree within the left-hemispheric cingulate and the left lateral and right medial orbitofrontal cortex.

CONCLUSION AND INFERENCES

These findings lend support to the hypothesis that CD is accompanied by alterations in both global network organization and regional connectivity. A deeper understanding of neural central networks in IBD may facilitate the development of complementary strategies in the treatment of "extraintestinal" comorbid conditions such as depression or anxiety.

A Verbal Fluency Task-Based Brain Activation fMRI Study in Patients with Crohn's Disease in Remission

BACKGROUND AND PURPOSE

In this pilot study, we investigated functional brain activation changes in patients with Crohn's disease (CD) in remission compared to age and gender-matched healthy controls (HCs).

METHODS

Data from 20 patients with CD in remission (age range 19-63 years) and 20 HCs (matched in age and gender) were analyzed. Task functional MRI (fMRI) data were collected while participants performed a cognitive (phonemic verbal fluency) task in the scanner. All participants also performed the same task outside the scanner.

RESULTS

Task fMRI results showed greater bi-hemispheric activation in CD patients compared to controls. Because this pattern is commonly reported with normal aging, we performed further analyses to investigate fMRI responses in a subset of the younger CD patients (N = 12, age < = 35 years) compared to matched young HCs (age < = 35 years), and an older cohort of HCs (age > = 50 years). Results showed that task activation patterns were similar between young CD patients and older HCs, and that both groups differed significantly from younger HCs. Activation intensity in specific brain regions for patients was associated with disease duration.

CONCLUSIONS

These results suggest that CD patients in remission may show accelerated signs of aging in terms of brain responses to a typical cognitive task. Future work with larger sample size will need to replicate these results as well as investigate the influence of factors, such as chronicity of the disease and medication effects on task-associated brain activation patterns in this patient population.

Central hypersensitivity - A model for persistent musculoskeletal pain in inflammatory bowel diseases

Pain is reported to affect over 70% of individuals with inflammatory bowel diseases (IBD), with abdominal and musculoskeletal (MSK) pain representing the most common complaints. MSK pain is typically considered within the narrow framework of inflammatory extraintestinal manifestations of IBD, resulting in a limited scope for the nature and underlying mechanisms participating in MSK pain experiences in this population. Symptoms related to central sensitization have recently demonstrated association with active IBD and worse MSK pain experiences, suggesting a potential roll for central mechanisms in MSK-related pain. Current literature exploring persistent pain in chronic inflammatory and MSK populations propose complex pain models comprised of dynamic nervous system relationships influenced by primary disease features and concomitant pain states, as well as affective and cognitive components. Nervous system contributions in the development and maintenance of persistent pain are postulated to include mechanisms of peripheral and central sensitization, changes in descending central modulation, as well as structural brain changes. These models go beyond current MSK pain models described in IBD literature, highlighting the need for new frameworks for considering MSK-related pain in IBD. Consequently, this paper proposes a broader theoretical model whereby central mechanisms, such as central sensitization and grey matter changes, as well as psychological and disease factors are suggested to modulate pain experiences in this population. Exploration of relationships within the proposed framework may provide not only a deeper understanding of the generation and maintenance of persistent MSK pain in IBD, but also highlight the need for new targeted management pathways in this population. This paper hypothesizes that exploration of central sensitization in IBD patients will demonstrate altered somatosensory functioning in patients with MSK pain, and that IBD activity and psychological factors will be associated with altered somatosensory functioning and worse pain experiences.

The Physical Burden of Immunoperception

The previous chapter introduced the ImmunoEmotional Regulatory System (IMMERS). Also, there was a brief discussion about psychological states/psychiatric disorders that so far have been linked to the IMMERS. The present chapter considers another aspect of the IMMERS in which physiological states/physical diseases can be fit to the IMMERS.

Difference in regional neural fluctuations and functional connectivity in Crohn's disease: a resting-state functional MRI study

Patients with Crohn's disease (CD) are shown to have abnormal changes in brain structures. This study aimed to further investigate whether these patients have abnormal brain activities and network connectivity. Sixty patients with CD and 40 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (fMRI) scans. Amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity (FC) were used to assess differences in spontaneous regional brain activity and functional connectivity. Compared to the HCs, patients with CD showed significantly higher ALFF values in hippocampus and parahippocampus (HIPP/paraHIPP), anterior cingulate cortex, insula, superior frontal cortex and precuneus. The ALFF values were significantly lower in secondary somatosensory cortex (S2), precentral gyrus, and medial prefrontal cortex. Functional connectivities between left HIPP and left inferior temporal cortex, and right middle cingulate cortex, HIPP, and fusiform area were significantly lower. The functional connectivities between right HIPP and right inferior orbitofrontal cortex and left HIPP were also significantly lower. Patients with CD showed higher or lower spontaneous activity in multiple brain regions. Altered activities in these brain regions may collectively reflect abnormal function and regulation of visceral pain and sensation, external environmental monitoring, and cognitive processing in these patients. Lower functional connectivity of the hippocampus-limbic system was observed in these patients. These findings may provide more information to elucidate the neurobiological mechanisms of the disease.

Progression of Structural Brain Changes in Patients With Chronic Pancreatitis and Its Association to Chronic Pain: A 7-Year Longitudinal Follow-up Study

OBJECTIVES

Temporal information about the structural brain changes in chronic pancreatitis (CP) and its relation to the clinical manifestations is lacking. This study investigated changes in morphological brain parameters over 7 years in painful CP patients, compared with controls.

METHODS

In this 7-year longitudinal magnetic resonance imaging study, we included 23 CP patients and 14 controls. Gray matter volume (GMV) and cortical thickness were examined using voxel-based and surface-based morphometry. In addition, patients completed pain questionnaires and diary.

RESULTS

At baseline, patients had reduced GMV and cortical thickness in widespread brain areas compared with controls. After 7 years of follow-up, the GMV loss was more pronounced in patients compared with controls, particularly in precentral gyrus and putamen. Moreover, an increase in pain scores was associated with a less reduction of thalamic GMV (P = 0.046), whereas an increase in brief pain inventory score was associated with more reduction in cortical thickness of precentral (P = 0.005) and superior temporal gyri (P = 0.019), indicating that brain morphological alterations are associated with the pain.

CONCLUSIONS

Chronic pancreatitis pain is associated with morphological brain changes over time in several areas, reflecting that brain plasticity may be a consequence of repeated long-term nociceptive signaling.

Colitis-induced alterations in response properties of visceral nociceptive neurons in the rat caudal medulla oblongata and their modulation by 5-HT3 receptor blockade

There is considerable clinical and experimental evidence that intestinal inflammation is associated with altered visceral nociceptive processing in the spinal cord and brain, but the underlying neuronal mechanisms, especially acting at the supraspinal level, remain unclear. Considering that the caudal ventrolateral medulla (CVLM) and the nucleus tractus solitarius (NTS) are the first sites for supraspinal processing of visceral pain signals, in the present study we evaluated the experimental colitis-induced changes in response properties of CVLM and NTS medullary neurons to noxious colorectal distension (CRD) in urethane-anesthetized adult male Wistar rats. To determine if gut inflammation alters the 5-HT₃ receptor-dependent modulation of visceral pain-related CVLM and NTS cells, we examined the effects of intravenously administered selective 5-HT₃ antagonist granisetron on ongoing and CRD-evoked activity of CVLM and NTS neurons in healthy control and colitic animals. In the absence of colonic pathology, the CVLM neurons were more excited by noxious CRD that the NTS cells, which demonstrated a greater tendency to be inhibited by the stimulation. The difference was eliminated after the development of colitis due to the increase in the proportion of CRD-excited neurons in both medullary regions associated with enhanced magnitude of the neuronal nociceptive responses. Intravenous granisetron (1 or 2 mg/kg) produced the dose-dependent suppression of the ongoing and evoked firing of CRD-excited cells within both the CVLM and NTS in normal conditions as well as was able to substantially reduce excitability of the caudal medullary neurons in the presence of colonic inflammation, arguing for the potential efficacy of the 5-HT₃ receptor blockade with granisetron against both acute and inflammatory abdominal pain. Taken together, the data obtained can contribute to a deeper understanding of supraspinal serotonergic mechanisms responsible for the persistence of visceral hypersensitivity and hyperalgesia triggered by colonic inflammation.

Cortical differences in diverticular disease and correlation with symptom reports

BACKGROUND

Recent studies have shown that the brain of patients with gastrointestinal disease differ both structurally and functionally from that of controls. Highly somatizing diverticular disease (HSDD) patients were also shown to differ from low somatizing (LSDD) patients functionally. This study aimed to investigate how they differed structurally.

METHODS

Four diseases subgroups were studied in a cross-sectional design: 20 patients with asymptomatic diverticular disease (ADD), 18 LSDD, 16 HSDD, and 18 with irritable bowel syndrome. We divided DD patients into LSDD and HSDD using a cutoff of 6 on the Patient Health Questionnaire 12 Somatic Symptom (PHQ12-SS) scale. All patients underwent a 1-mm isotropic structural brain MRI scan and were assessed for somatization, hospital anxiety, depression, and pain catastrophizing. Whole brain volumetry, cortical thickness analysis and voxel-based morphometry were carried out using Freesurfer and SPM.

KEY RESULTS

We observed decreases in gray matter density in the left and right dorsolateral prefrontal cortex (dlPFC), and in the mid-cingulate and motor cortex, and increases in the left (19, 20) and right (19, 38) Brodmann Areas. The average cortical thickness differed overall across groups (P = .002) and regionally: HSDD > ADD in the posterior cingulate cortex (P = .03), HSDD > LSDD in the dlPFC (P = .03) and in the ventrolateral PFC (P < .001). The thickness of the anterior cingulate cortex and of the mid-prefrontal cortex were also found to correlate with Pain Catastrophizing (Spearman's ρ = 0.24, P = .043 uncorrected and Spearman's ρ = 0.25, P = .03 uncorrected).

CONCLUSION & INFERENCES

This is the first study of structural gray matter abnormalities in diverticular disease patients. The data show brain differences in the pain network.

Evaluation of Chronic Pain Using Magnetic Resonance (MR) Neuroimaging Approaches: What the Clinician Needs to Know

OBJECTIVES

Numerous neuroimaging techniques have been recently used to investigate central mechanisms involved in pain perception and to examine morphological and functional brain alterations associated with chronic pain. Compared to self-reporting approaches, objective imaging techniques are expected to potentially lead to better pain assessment and guide management. This comprehensive scoping review aims to identify recent magnetic resonance imaging (MRI) approaches that have been used to characterize the brain of chronic pain subjects, using structural, chemical and functional MRI techniques.

METHODS

A systematic search and review of the literature was conducted and the resultant studies were critically examined for relevance.

RESULTS

MRI neuroimaging of various chronic pain conditions were summarized. We classified the collected studies into: structural brain alterations, VBM (voxel based morphology) examination of structural changes, DTI, changes in brain chemistry, functional and blood flow brain alterations.

DISCUSSION

From our clinical experience, we have noted that most clinicians are not aware of the capabilities of advanced MRI methods in assessing cortical manifestations of chronic pain. In addition, many clinicians are not aware of the cortical alterations present in individuals with chronic pain. This comprehensive scoping review thus sets out to first summarize MRI neuroimaging techniques that are available in the current literature to examine chronic pain. We then identify cortical MR approaches that have been able to reliably predict transition from acute to chronic pain. Finally, we summarize MRI neuroimaging techniques that have been used to track treatment response of individuals with chronic pain.

How do morphological alterations caused by chronic pain distribute across the brain? A meta-analytic co-alteration study

•In chronic pain, gray matter (GM) alterations are not distributed randomly across the brain.•The pattern of co-alterations resembles that of brain connectivity.•The alterations' distribution partly rely on the pathways of functional connectivity.•This method allows us to identify tendencies in the distribution of GM co-alteration related to chronic pain.