Transcranial direct current stimulation in inflammatory bowel disease patients modifies resting-state functional connectivity: A RCT

Brain network topological changes in inflammatory bowel disease: an exploratory study

Although the aetio-pathogenesis of inflammatory bowel diseases (IBD) is not entirely clear, the interaction between genetic and adverse environmental factors may induce an intestinal dysbiosis, resulting in chronic inflammation having effects on the large-scale brain network. Here, we hypothesized inflammation-related changes in brain topology of IBD patients, regardless of the clinical form [ulcerative colitis (UC) or Crohn's disease (CD)]. To test this hypothesis, we analysed source-reconstructed magnetoencephalography (MEG) signals in 25 IBD patients (15 males, 10 females; mean age ± SD, 42.28 ± 13.15; mean education ± SD, 14.36 ± 3.58) and 28 healthy controls (HC) (16 males, 12 females; mean age ± SD, 45.18 ± 12.26; mean education ± SD, 16.25 ± 2.59), evaluating the brain topology. The betweenness centrality (BC) of the left hippocampus was higher in patients as compared with controls, in the gamma frequency band. It indicates how much a brain region is involved in the flow of information through the brain network. Furthermore, the comparison among UC, CD and HC showed statistically significant differences between UC and HC and between CD and HC, but not between the two clinical forms. Our results demonstrated that these topological changes were not dependent on the specific clinical form, but due to the inflammatory process itself. Broader future studies involving panels of inflammatory factors and metabolomic analyses on biological samples could help to monitor the brain involvement in IBD and to clarify the clinical impact.

The Role of the Insula in Chronic Pain and Associated Structural Changes: An Integrative Review

Chronic pain affects a substantial portion of the global population, significantly impacting quality of life and well-being. This condition involves complex mechanisms, including dysfunction of the autonomic nervous system, which plays a crucial role in pain perception. The insula, a key brain region involved in pain processing, plays a critical role in pain perception and modulation. Lesions in the insula can result in pain asymbolia, where pain perception remains intact but emotional responses are inappropriate. The insula is anatomically and functionally divided into anterior and posterior regions, with the posterior insula processing nociceptive input based on intensity and location before relaying it to the anterior insula for emotional mediation. Understanding the insula's intricate role in pain processing is crucial, as it is involved in encoding prediction errors and mediating emotional dimensions of pain perception. The focus of this review was on synthesizing existing literature on the role of the insula in chronic pain and associated structural changes. The goal was to integrate findings from various sources to provide a comprehensive overview of the topic. The search strategy included a combination of Medical Subject Headings (MeSH) and relevant keywords related to insula and chronic pain. The following databases were surveyed: PubMed, Embase, Scopus, and Web of Science. We identified a total of 2515 articles, and after following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline based on eligibility criteria, 46 articles were used to synthesize this review. Our study highlights the pivotal role of the insula in chronic pain processing and associated structural changes, integrating findings from diverse studies and neuroimaging investigations. Beyond mere pain sensation, the insula contributes to emotional awareness, attention, and salience detection within the pain network. Various chronic pain conditions reveal alterations in insular activity and connectivity, accompanied by changes in gray matter volume and neurochemical profiles. Interventions targeting the insula show promise in alleviating chronic pain symptoms. However, further research is needed to understand underlying mechanisms, which can aid in developing more effective therapeutic interventions for pain.

Brain signatures of chronic gut inflammation

Gut inflammation is thought to modify brain activity and behaviour via modulation of the gut-brain axis. However, how relapsing and remitting exposure to peripheral inflammation over the natural history of inflammatory bowel disease (IBD) contributes to altered brain dynamics is poorly understood. Here, we used electroencephalography (EEG) to characterise changes in spontaneous spatiotemporal brain states in Crohn's Disease (CD) (n = 40) and Ulcerative Colitis (UC) (n = 30), compared to healthy individuals (n = 28). We first provide evidence of a significantly perturbed and heterogeneous microbial profile in CD, consistent with previous work showing enduring and long-standing dysbiosis in clinical remission. Results from our brain state assessment show that CD and UC exhibit alterations in the temporal properties of states implicating default-mode network, parietal, and visual regions, reflecting a shift in the predominance from externally to internally-oriented attentional modes. We investigated these dynamics at a finer sub-network resolution, showing a CD-specific and highly selective enhancement of connectivity between the insula and medial prefrontal cortex (mPFC), regions implicated in cognitive-interoceptive appraisal mechanisms. Alongside overall higher anxiety scores in CD, we also provide preliminary support to suggest that the strength of chronic interoceptive hyper-signalling in the brain co-occurs with disease duration. Together, our results demonstrate that a long-standing diagnosis of CD is, in itself, a key factor in determining the risk of developing altered brain network signatures.

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.

Multielectrode Network Stimulation (ME-NETS) demonstrated by concurrent tDCS and fMRI

Non-invasive transcranial direct current stimulation (tDCS) can modulate activity of targeted brain regions. Whether tDCS can reliably and repeatedly modulate intrinsic connectivity of entire brain networks is unclear. We used concurrent tDCS-MRI to investigate the effect of high dose anodal tDCS on resting state connectivity within the Arcuate Fasciculus (AF) network, which spans the temporal, parietal, and frontal lobes and is connected via a structural backbone, the Arcuate Fasciculus (AF) white matter tract. Effects of high-dose tDCS (4mA) delivered via a single electrode placed over one of the AF nodes (single electrode stimulation, SE-S) was compared to the same dose split between multiple electrodes placed over AF-network nodes (multielectrode network stimulation, ME-NETS). While both SE-S and ME-NETS significantly modulated connectivity between AF network nodes (increasing connectivity during stimulation epochs), ME-NETS had a significantly larger and more reliable effect than SE-S. Moreover, comparison with a control network, the Inferior Longitudinal Fasciculus (ILF) network suggested that the effect of ME-NETS on connectivity was specific to the targeted AF-network. This finding was further supported by the results of a seed-to-voxel analysis wherein we found ME-NETS primarily modulated connectivity between AF-network nodes. Finally, an exploratory analysis looking at dynamic connectivity using sliding window correlation found strong and immediate modulation of connectivity during three stimulation epochs within the same imaging session.

Cortical mechanisms of visual hypersensitivity in women at risk for chronic pelvic pain

ABSTRACT

Increased sensory sensitivity across non-nociceptive modalities is a common symptom of chronic pain conditions and is associated with chronic pain development. Providing a better understanding of the brain-behavior relationships that underlie multimodal hypersensitivity (MMH) may clarify the role of MMH in the development of chronic pain. We studied sensory hypersensitivity in a cohort of women (n = 147) who had diary confirmation of menstrual status and were enriched with risk factors for chronic pelvic pain, such as dysmenorrhea and increased bladder sensitivity. We administered 2 experimental tasks to evaluate the cross-modal relationship between visual and visceral sensitivity. Visual sensitivity was probed by presenting participants with a periodic pattern-reversal checkerboard stimulus presented across 5 brightness intensities during electroencephalography recording. Self-reported visual unpleasantness ratings for each brightness intensity were simultaneously assessed. Visceral sensitivity was evaluated with an experimental bladder-filling task associated with early clinical symptoms of chronic pelvic pain. Visually evoked cortical activity increased with brightness intensity across the entire scalp, especially at occipital electrode sites. Visual stimulation-induced unpleasantness was associated with provoked bladder pain and evoked primary visual cortex activity. However, the relationship between unpleasantness and cortical activity was moderated by provoked bladder pain. These results demonstrate that activity in the primary visual cortex is not greater in individuals with greater visceral sensitivity. We hypothesize that downstream interpretation or integration of this signal is amplified in individuals with visceral hypersensitivity. Future studies aimed at reducing MMH in chronic pain conditions should prioritize targeting of cortical mechanisms responsible for aberrant downstream sensory integration.

Reducing Pain in Experimental Models of Intestinal Inflammation Affects the Immune Response

The incidence of inflammatory bowel disease with its two main manifestations, colitis ulcerosa and Crohn's disease, is rising globally year after year. There is still a tremendous need to study the underlying pathomechanisms and a well-established tool in order to better understand the disease are colitis models in rodents. Since the concept of the 3Rs was proposed by Russell and Burch, this would include pain medication in animal models of intestinal inflammation as a reduction of suffering. This review argues against pain medication because the administration of pain medication in its current form has an impact on the inflammatory process and the immune response, thus falsifying the results and the reproducibility and therefore leading to misconceptions.

Is it time to include older adults in inflammatory bowel disease trials? A call for action

The therapeutic management of older patients with inflammatory bowel disease (IBD) is challenging, particularly because of the absence of evidence-based guidelines for these patients, who seem to frequently be excluded from clinical trials. In this systematic review we investigated the exclusion of older patients with IBD from phase 3 studies registered on PubMed and ClinicalTrials.gov, by assessing the upper limit of age exclusion criteria and the percentage of patients older than 65 years included in the trials. Exclusion criteria other than age were also recorded, and comorbidities were analysed separately. Our review of 222 phase 3 studies shows that older patients are frequently excluded from IBD clinical trials because of their age, which was used as an exclusion criterion in 129 (58%) of the 222 assessed trials. Of the 32 trials that detailed the percentage of included patients who were 65 years or older, only 763 (5·4%) patients of the 14 124 patients included were older than 65 years. In addition to age, patients were also excluded because of comorbidities (mainly renal, hepatic, and cardiovascular, and used as an exclusion criterion in 76% of trials), a history of dysplasia (45% of trials), and previous treatment for IBD (19% of trials). We propose a three-step process that should enable the inclusion of all older patients in IBD clinical trials, regardless of their age, comorbidities, and frailty.

Common psychological issues and management in patients with inflammatory bowel disease

Patients with inflammatory bowel disease (IBD) have a significantly higher incidence of psychological issues than the general population. Anxiety and depression are the most common psychological problems. These psychological problems have an adverse impact on the quality of life and prognosis of IBD patients. Low quality of life and complex course of disease also aggravate patients' anxiety and depression. The disorder of the brain-gut axis is the important mechanism in bi-directional interactions between IBD disease activity and psychological issues. More and more attention has been paid to the diagnostic approaches for psychological conditions and standardized management in IBD. This article reviews the common psychological issues in IBD patients, the interactions between psychological issues and IBD disease activity, and related management of psychological problems in patients with IBD.

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.

Interventions for the management of abdominal pain in Crohn's disease and inflammatory bowel disease

BACKGROUND

Crohn's disease is a remitting and relapsing disorder that can affect the whole gastrointestinal tract. Active disease symptoms include abdominal pain, fatigue, weight loss, and diarrhoea. There is no known cure; however, the disease can be managed, and therefore places a huge financial burden on healthcare systems. Abdominal pain is a common and debilitating symptom of Crohn's and other inflammatory bowel diseases (IBDs), and is multifaceted. Abdominal pain in Crohn's disease could be a symptom of disease relapse or related to medication adverse effects, surgical complications and strictures or adhesions secondary to IBD. In the absence of these factors, around 20 to 50% of people with Crohn's in remission still experience pain.

OBJECTIVES

To assess the efficacy and safety of interventions for managing abdominal pain in people with Crohn's disease and IBD (where data on ulcerative colitis and Crohn's disease could not be separated).

SEARCH METHODS

We searched CENTRAL, MEDLINE, three other databases, and clinical trials registries on 29 April 2021. We also searched the references of trials and systematic reviews for any additional trials.

SELECTION CRITERIA

All published, unpublished, and ongoing randomised trials that compared interventions for the management of abdominal pain in the setting of Crohn's disease and IBD, with other active interventions or standard therapy, placebo, or no therapy were included. We excluded studies that did not report on any abdominal pain outcomes.

DATA COLLECTION AND ANALYSIS

Five review authors independently conducted data extraction and 'Risk of bias' assessment of the included studies. We analysed data using Review Manager 5. We expressed dichotomous and continuous outcomes as risk ratios and mean differences with 95% confidence intervals. We assessed the certainty of the evidence using GRADE methodology.

MAIN RESULTS

We included 14 studies (743 randomised participants). Five studies evaluated participants with Crohn's disease; seven studies evaluated participants with IBD where the data on ulcerative colitis and Crohn's disease could not be separated; and two studies provided separate results for Crohn's disease participants. Studies considered a range of disease activity states. Two studies provided intervention success definitions, whilst the remaining studies measured pain as a continuous outcome on a rating scale. All studies except one measured pain intensity, whilst three studies measured pain frequency. Withdrawals due to adverse events were directly or indirectly reported in 10 studies. No conclusions could be drawn about the efficacy of the majority of the interventions on pain intensity, pain frequency, and treatment success, except for the comparison of transcranial direct current stimulation to sham stimulation. The certainty of the evidence was very low in all but one comparison because of imprecision due to sparse data and risk of bias assessed as unclear or high risk. Two studies compared a low FODMAP diet (n=37) to a sham diet (n=45) in IBD patients. The evidence on pain intensity was of very low certainty (MD -12.00, 95% CI -114.55 to 90.55). One study reported pain intensity separately for CD participants in the low FODMAP group [n=14, mean(SD)=24 (82.3)] and the sham group [n=12, mean(SD)=32 (69.3)]. The same study also reported pain frequency for IBD participants in the low FODMAP group [n=27, mean(SD)=36 (26)] and sham group [n=25, mean(SD)=38(25)] and CD participants in the low FODMAP group [n=14, mean(SD)=36 (138.4)] and sham group [n=12, mean(SD)=48 (128.2)]. Treatment success was not reported. One study compared a low FODMAP diet (n=25) to high FODMAP/normal diet (n=25) in IBD patients. The data reported on pain intensity was unclear. Treatment success and pain frequency were not reported. One study compared medicine-separated moxibustion combined with acupuncture (n=51) versus wheat bran-separated moxibustion combined with shallow acupuncture (n=51) in CD patients. The data reported on pain intensity and frequency were unclear. Treatment success was not reported. One study compared mindfulness with CBT (n=33) versus no treatment (n=33) in IBD patients. The evidence is very uncertain about the effect of this treatment on pain intensity and frequency (MD -37.00, 95% CI -87.29 to 13.29). Treatment success was not reported. One study compared soft non-manipulative osteopathic treatment (n=16) with no treatment besides doctor advice (n=14) in CD patients. The evidence is very uncertain about the effect of this treatment on pain intensity (MD 0.01, 95% CI -1.81 to 1.83). Treatment success and pain frequency were not reported. One study compared stress management (n=15) to self-directed stress management(n=15) and to standard treatment (n=15) in CD patients. The evidence is very uncertain about the effect of these treatments on pain intensity (MD -30.50, 95% CI -58.45 to -2.55 and MD -34.30, 95% CI -61.99 to -6.61). Treatment success and pain frequency were not reported. One study compared enteric-release glyceryl trinitrate (n=34) with placebo (n=36) in CD patients. The data reported on pain intensity was unclear. Treatment success and pain frequency were not reported.  One study compared 100 mg olorinab three times per day (n=8) with 25 mg olorinab three times per day (n=6) in CD patients. Pain intensity was measured as a 30% reduction in weekly average abdominal pain intensity score for the 100mg group (n=5) and the 25mg group (n=6). The evidence is very uncertain about the effect of this treatment on pain intensity (RR 0.66, 95% CI 0.38 to 1.15). Treatment success and pain frequency were not reported. One study compared relaxation training (n=28) to a waitlist (n=28) in IBD patients. The evidence is very uncertain about the effect of this treatment on pain intensity (MD -0.72, 95% CI -1.85 to 0.41). Treatment success and pain frequency were not reported. One study compared web-based education (n=30) with a book-based education (n=30) in IBD patients. The evidence is very uncertain about the effect of this treatment on pain intensity (MD -0.13, 95% CI -1.25 to 0.99). Treatment success and pain frequency were not reported. One study compared yoga (n=50) with no treatment (n=50) in IBD patients. The data reported on treatment success were unclear. Pain frequency and intensity were not reported. One study compared transcranial direct current stimulation (n = 10) to sham stimulation (n = 10) in IBD patients. There may be an improvement in pain intensity when transcranial direct current is compared to sham stimulation (MD -1.65, 95% CI -3.29 to -0.01, low-certainty evidence). Treatment success and pain frequency were not reported. One study compared a kefir diet (Lactobacillus bacteria) to no intervention in IBD patients and provided separate data for their CD participants. The evidence is very uncertain about the effect of this treatment on pain intensity in IBD (MD 0.62, 95% CI 0.17 to 1.07) and CD (MD -1.10, 95% CI -1.67 to -0.53). Treatment success and pain frequency were not reported. Reporting of our secondary outcomes was inconsistent. The most adverse events were reported in the enteric-release glyceryl trinitrate and olorinab studies.  In the enteric-release glyceryl trinitrate study, the adverse events were higher in the intervention arm. In the olorinab study, more adverse events were observed in the higher dose arm of the intervention.  In the studies on non-drug interventions, adverse events tended to be very low or zero. However, no clear judgements regarding adverse events can be drawn for any interventions due to the low number of events. Anxiety and depression were measured and reported at the end of intervention in only one study; therefore, no meaningful conclusions can be drawn for this outcome.

AUTHORS' CONCLUSIONS

We found low certainty evidence that transcranial direct current stimulation may improve pain intensity compared to sham stimulation. We could not reach any conclusions on the efficacy of any other interventions on pain intensity, pain frequency, and treatment success. The certainty of the evidence was very low due to the low numbers of studies and participants in each comparison and clinical heterogeneity amongst the studies. While no serious or total adverse events were elicited explicitly with any of the treatments studied, the reported events were very low. The certainty of the evidence for all comparisons was very low, so no conclusions can be drawn.

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.

Post-inflammatory Abdominal Pain in Patients with Inflammatory Bowel Disease During Remission: A Comprehensive Review

Patients with inflammatory bowel disease often experience ongoing pain even after achieving mucosal healing (i.e., post-inflammatory pain). Factors related to the brain-gut axis, such as peripheral and central sensitization, altered sympatho-vagal balance, hypothalamic-pituitary-adrenal axis activation, and psychosocial factors, play a significant role in the development of post-inflammatory pain. A comprehensive study investigating the interaction between multiple predisposing factors, including clinical psycho-physiological phenotypes, molecular mechanisms, and multi-omics data, is still needed to fully understand the complex mechanism of post-inflammatory pain. Furthermore, current treatment options are limited and new treatments consistent with the underlying pathophysiology are needed to improve clinical outcomes.

Interventions for the management of abdominal pain in ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammation of the colon characterised by periods of relapse and remission. It starts in the rectum and can extend throughout the colon. UC and Crohn's disease (CD) are the most common inflammatory bowel diseases (IBDs). However, UC tends to be more common than CD. It has no known cure but can be managed with medication and surgery. However, studies have shown that abdominal pain persists in up to one-third of people with UC in remission. Abdominal pain could be a symptom of relapse of the disease due to adverse effects of medication, surgical complications and strictures or adhesions secondary to UC.

OBJECTIVES

To assess the efficacy and safety of interventions for managing abdominal pain in people with ulcerative colitis.

SEARCH METHODS

We searched CENTRAL, MEDLINE and five other databases and clinical trials registries on 28 April 2021. We contacted authors of relevant studies and ongoing or unpublished trials that may be relevant to the review. We also searched references of trials and systematic reviews for any additional trials.

SELECTION CRITERIA

All published, unpublished and ongoing randomised trials that compared interventions for the management of abdominal pain with other active interventions or standard therapy, placebo or no therapy were included. People with both active and inactive disease were included. We excluded studies that did not report on any abdominal pain outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently conducted data extraction and 'Risk of bias' assessments. We analysed data using Review Manager 5. We expressed dichotomous and continuous outcomes as risk ratios (RRs) and mean differences (MDs), respectively, with 95% confidence intervals. We assessed the certainty of the evidence using the GRADE methodology.

MAIN RESULTS

We included five studies (360 randomised participants). Studies considered mainly participants in an inactive state of the disease.   No conclusions could be drawn about the efficacy of any of the interventions on pain frequency, pain intensity, and treatment success. The certainty of the evidence was very low for all comparisons because of imprecision due to sparse data, and risk of bias. One study compared a low FODMAPs diet (n=13) to a sham diet (n=13). The evidence is very uncertain about the effect of this treatment on pain frequency (MD -4.00, 95% CI -20.61 to 12.61) and intensity (MD -9.00, 95% CI -20.07 to 2.07). Treatment success was not reported. One study compared relaxation training (n=20) to wait-list (n=20). The evidence is very uncertain about the effect of this treatment on pain frequency at end of intervention (MD 2.60, 95% CI 1.14 to 4.06) and 6-month follow-up (MD 3.30, 95% CI 1.64 to 4.96). Similarly, the evidence is very uncertain about the effect of this treatment on pain intensity at end of intervention (MD -1.70, 95% CI -2.92 to -0.48) and 6-month follow-up (MD -2.30, 95% CI -3.70 to -0.90). Treatment success was not reported. One study compared yoga (n=30) to no intervention (n=30). The study defined treatment success as the presence or absence of pain; however, the data they provided was unclear. Pain frequency and intensity were not reported. One study compared a kefir diet (Lactobacillus bacteria, n=15) to no intervention (n=15). The evidence is very uncertain about the effect of this treatment on pain intensity (MD -0.17, 95% CI -0.91 to 0.57). Pain frequency and treatment success were not reported. One study compared a stellate ganglion block treatment (n=90) to sulfasalazine treatment (n=30). The study defined treatment success as "stomachache"; however, the data they provided was unclear. Pain frequency and intensity were not reported. Two studies reported withdrawals due to adverse events. One study reported withdrawals due to adverse events as zero. Two studies did not report this outcome.  We cannot draw any conclusions about the effects of any of the interventions on withdrawals due to adverse events because of the very limited evidence. The reporting of secondary outcomes was inconsistent. Adverse events tended to be very low or zero. However, we can make no clear judgements about adverse events for any of the interventions, due to the low number of events. Anxiety was measured and reported at end of intervention in only one study (yoga versus no intervention), and depression was not measured in any of the studies. We can therefore draw no meaningful conclusions about these outcomes.

AUTHORS' CONCLUSIONS

We found very low-certainty evidence on the efficacy and safety of interventions for the management of abdominal pain in ulcerative colitis. Pervasive issues with very serious imprecision from small samples size and high risk of bias have led to very low-certainty outcomes, precluding conclusions. While few adverse events and no serious adverse events were reported, the certainty of these findings was again very low for all comparisons, so no conclusions can be drawn. There is a need for further research. We have identified eight ongoing studies in this review, so an update will be warranted. It is key that future research addresses the issues leading to reduced certainty of outcomes, specifically sample size and reporting that leads to high risk of bias. It is also important that if researchers are considering pain as a critical outcome, they should report clearly if participants were pain-free at baseline; in that case, data would be best presented as separate subgroups throughout their research.

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.

Cortical Mechanisms of Visual Hypersensitivity in Women at Risk for Chronic Pelvic Pain

Multisensory hypersensitivity (MSH), which refers to persistent discomfort across sensory modalities, is a risk factor for chronic pain. Developing a better understanding of the neural contributions of disparate sensory systems to MSH may clarify its role in the development of chronic pain. We recruited a cohort of women (n=147) enriched with participants with menstrual pain at risk for developing chronic pain. Visual sensitivity was measured using a periodic pattern-reversal stimulus during EEG. Self-reported visual unpleasantness ratings were also recorded. Bladder pain sensitivity was evaluated with an experimental bladder-filling task associated with early clinical symptoms of chronic pelvic pain. Visual stimulation induced unpleasantness was associated with bladder pain and evoked primary visual cortex excitation; however, the relationship between unpleasantness and cortical excitation was moderated by bladder pain. Thus, future studies aimed at reversing the progression of MSH into chronic pain should prioritize targeting of cortical mechanisms responsible for maladaptive sensory input integration.

Repeated Sessions of Transcranial Direct Current Stimulation on Adolescents With Autism Spectrum Disorder: Study Protocol for a Randomized, Double-Blind, and Sham-Controlled Clinical Trial

Background: Social-emotional difficulties are a core symptom of autism spectrum disorder (ASD). Accordingly, individuals with ASD have problems with social cognition such as recognizing emotions from other peoples' faces. Various results from functional magnetic resonance imaging and electroencephalography studies as well as eye-tracking data reveal a neurophysiological basis of these deficits by linking them to abnormal brain activity. Thus, an intervention targeting the neural origin of ASD impairments seems warranted. A safe method able to influence neural activity is transcranial direct current stimulation (tDCS). This non-invasive brain stimulation method has already demonstrated promising results in several neuropsychiatric disorders in adults and children. The aim of this project is to investigate the effects of tDCS on ASD symptoms and their neural correlates in children and adolescents with ASD. Method: This study is designed as a double-blind, randomized, and sham-controlled trial with a target sample size of 20 male participants (aged 12-17 years) diagnosed with ASD. Before randomization, the participants will be stratified into comorbid depression, comorbid ADHS/conduct disorder, or no-comorbidity groups. The intervention phase comprises 10 sessions of anodal or sham tDCS applied over the left prefrontal cortex within 2 consecutive weeks. To engage the targeted brain regions, participants will perform a social cognition training during the stimulation. TDCS-induced effects on ASD symptoms and involved neural circuits will be investigated through psychological, neurophysiological, imaging, and behavioral data at pre- and post-measurements. Tolerability will be evaluated using a standardized questionnaire. Follow-up assessments 1 and 6 months after the intervention will examine long-lasting effects. Discussion: The results of this study will provide insights into the changeability of social impairments in ASD by investigating social and emotional abilities on different modalities following repeated sessions of anodal tDCS with an intra-simulation training. Furthermore, this trial will elucidate the tolerability and the potential of tDCS as a new treatment approach for ASD in adolescents. Clinical Trial Registration: The study is ongoing and has been registered in the German Registry of Clinical Trials (DRKS00017505) on 02/07/2019.

The Effect of Transcranial Direct Current Stimulation in Changing Resting-State Functional Connectivity in Patients With Neurological Disorders: A Systematic Review

BACKGROUND

People with neurological disorders are found to have abnormal resting-state functional connectivity (rsFC), which is associated with the persistent functional impairment found in these patients. Recently, transcranial direct current stimulation (tDCS) has been shown to improve rsFC, although the results are inconsistent.

OBJECTIVE

We hope to explore whether tDCS induces rsFC changes among patients with neurological disorders, whether rsFC is clinically relevant and how different tDCS parameters affect rsFC outcome among these individuals.

METHODS

A systematic review was conducted according to PRISMA guidelines (systematic review registration number: CRD42020168654). Randomized controlled trials that studied the tDCS effects on rsFC between the experimental and sham-controlled groups using either electrophysiological or neuroimaging methods were included.

RESULTS

Active tDCS can induce changes in both localized (ie, brain regions under the transcranial electrodes) and diffused (ie, brain regions not directly influenced by the transcranial electrodes) rsFC. Interestingly, fMRI studies showed that the default mode network was enhanced regardless of patients' diagnoses, the stimulation paradigms used or the rsFC analytical methods employed. Second, stimulation intensity, but not total stimulation time, appeared to positively influence the effect of tDCS on rsFC.

LIMITATIONS AND CONCLUSION

Due to the inherent heterogeneity in rsFC analytical methods and tDCS protocols, meta-analysis was not conducted. We recommend that future studies may investigate the effect of tDCS on rsFC for repeated cathodal stimulation. For clinicians, we suggest anodal stimulation at a higher stimulation intensity within the safety limit may maximize tDCS effects in modulating aberrant functional connectivity of patients with neurological disorders.

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.

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.