Excessive coupling of the salience network with intrinsic neurocognitive brain networks during rectal distension in adolescents with irritable bowel syndrome: a preliminary report

Navigating through 65 years of insights: lessons learned on functional abdominal pain in children

In 1958, Apley and Naish authored a groundbreaking paper in Archives of Disease in Childhood, elucidating the epidemiology and risk factors of recurrent abdominal pain in children-a subject that had confounded clinicians of their time. Surprisingly, even after 65 years, there are several unanswered questions regarding the etiology, pathophysiology, and management of pediatric abdominal pain. Contrary to the prevailing notion that children naturally outgrow functional abdominal pain, compelling evidence suggests it's possible these children develop a number of clinically significant psychological issues that could profoundly impact their quality of life and, consequently, future health and educational outcomes. In this light, we aimed to comprehensively review the current literature to update the knowledge of practicing clinicians on functional abdominal pain, summarizing the evidence from the last 65 years.Conclusion: The enduring unanswered questions surrounding childhood abdominal pain continue to challenge clinicians, resulting in unnecessary investigations, thereby contributing to substantial healthcare expenditures. It is also evident that children with long-standing symptoms would progress to adulthood with the potential to develop irritable bowel syndrome and many psychological disturbances. Several key interventions using pharmacological agents, such as amitriptyline, showed that some of these drugs are no more effective than the placebo in clinical trials. Several research during the recent past suggest that psychological interventions such as gut-directed hypnotherapy alleviate symptoms and ensure better prognosis in the long run. Therefore, clinicians and researchers must join hands to explore the pathophysiological mechanisms underpinning functional abdominal pain and novel therapeutic strategies to ensure the well-being of these children. What is Known: • Functional abdominal pain disorders are common among children, with a worldwide prevalence of 13.5% of children suffering from at least one of these disorders • These disorders contribute to a significant reduction in the quality of life of affected children and their families and lead to an array of psychological problems What is New: • The biological basis of functional abdominal pain is becoming more explicit, including complex interactions between altered microbiome, deranged motility, and psychological dysfunction with gut-brain interactions • Novel approaches giving minimal emphasis on pharmacological interventions and exploring psychological interventions are showing promising results.

Study protocol for a pilot clinical trial to understand neural mechanisms of response to a psychological treatment for pain and anxiety in pediatric functional abdominal pain disorders (FAPD)

BACKGROUND

Functional abdominal pain disorders (FAPD) are the most common chronic pain conditions of childhood and are made worse by co-occurring anxiety. Our research team found that the Aim to Decrease Pain and Anxiety Treatment (ADAPT), a six-session coping skills program using cognitive behavioral therapy strategies, was effective in improving pain-related symptoms and anxiety symptoms compared to standard care. In follow-up, this current randomized clinical trial (RCT) aims to test potential neural mechanisms underlying the effect of ADAPT. Specifically, this two-arm RCT will explore changes in amygdalar functional connectivity (primary outcome) following the ADAPT protocol during the water loading symptom provocation task (WL-SPT). Secondary (e.g., changes in regional cerebral blood flow via pulsed arterial spin labeling MRI) and exploratory (e.g., the association between the changes in functional connectivity and clinical symptoms) outcomes will also be investigated.

METHODS

We will include patients ages 11 to 16 years presenting to outpatient pediatric gastroenterology care at a midwestern children's hospital with a diagnosis of FAPD plus evidence of clinical anxiety based on a validated screening tool (the Generalized Anxiety Disorder-7 [GAD-7] measure). Eligible participants will undergo baseline neuroimaging involving the WL-SPT, and assessment of self-reported pain, anxiety, and additional symptoms, prior to being randomized to a six-week remotely delivered ADAPT program plus standard medical care or standard medical care alone (waitlist). Thereafter, subjects will complete a post assessment neuroimaging visit similar in nature to their first visit.

CONCLUSIONS

This small scale RCT aims to increase understanding of potential neural mechanisms of response to ADAPT.

TRIAL REGISTRATION

ClinicalTrials.gov registration: NCT03518216.

Imaging in pediatric disorders of the gut-brain interactions: current best practice and future directions

INTRODUCTION

Disorders of Gut-Brain Interactions (DGBI) are a common clinical problem in children and pose significant challenges to the attending pediatrician. Radiological investigations are commonly ordered to evaluate these children.

AREA COVERED

This review focuses on the current best practice of using radiological investigations in DGBIs and how novel radiological investigations could revolutionize the assessment and therapeutic approach of DGBI in children.

EXPERT OPINION

We believe imaging in DGBI is still in its early stages, but it has the potential to revolutionize how we diagnose and treat children with DGBI. As the understanding of the gut-brain axis continues to grow, we can expect to see the disappearance of conventional imaging techniques and the emergence of more sophisticated imaging techniques with less radiation exposure in the future which provide more clinically meaningful information regarding the gut-brain axis and its influence on intestinal function. Some of the novel imaging modalities will be able to broaden our horizon of understanding DGBI in children providing more useful therapeutic options to minimize their suffering.

Functional changes of default mode network and structural alterations of gray matter in patients with irritable bowel syndrome: a meta-analysis of whole-brain studies

Background

Irritable bowel syndrome (IBS) is a brain-gut disorder with high global prevalence, resulting from abnormalities in brain connectivity of the default mode network and aberrant changes in gray matter (GM). However, the findings of previous studies about IBS were divergent. Therefore, we conducted a meta-analysis to identify common functional and structural alterations in IBS patients.

Methods

Altogether, we identified 12 studies involving 194 IBS patients and 230 healthy controls (HCs) from six databases using whole-brain resting state functional connectivity (rs-FC) and voxel-based morphometry. Anisotropic effect-size signed differential mapping (AES-SDM) was used to identify abnormal functional and structural changes as well as the overlap brain regions between dysconnectivity and GM alterations.

Results

Findings indicated that, compared with HCs, IBS patients showed abnormal rs-FC in left inferior parietal gyrus, left lingual gyrus, right angular gyrus, right precuneus, right amygdala, right median cingulate cortex, and left hippocampus. Altered GM was detected in the fusiform gyrus, left triangular inferior frontal gyrus (IFG), right superior marginal gyrus, left anterior cingulate gyrus, left rectus, left orbital IFG, right triangular IFG, right putamen, left superior parietal gyrus and right precuneus. Besides, multimodal meta-analysis identified left middle frontal gyrus, left orbital IFG, and right putamen as the overlapped regions.

Conclusion

Our results confirm that IBS patients have abnormal alterations in rs-FC and GM, and reveal brain regions with both functional and structural alterations. These results may contribute to understanding the underlying pathophysiology of IBS.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42022351342.

Abnormal cortical-striatal-thalamic-cortical circuit centered on the thalamus in MDD patients with somatic symptoms: Evidence from the REST-meta-MDD project

OBJECTIVE

Somatic symptoms are common comorbidities of major depressive disorder (MDD), and negatively impact the course and severity of the disease. In order to enrich the understanding of the pathological mechanism and clarify the neurobiological basis of somatic symptoms in depression, we attempted to explore the changes of brain structure and function in a large sample between depression with and without somatic symptoms.

METHODS

Structure magnetic resonance imaging (MRI) data were collected from 342 patients with somatic symptoms (SD), 208 patients without somatic symptoms (NSD), and 510 healthy controls (HCs) based on the REST-meta-MDD project. We analyzed the whole brain VBM maps of the three groups, and combined with weight degree centrality (DC) index, we investigated whether the brain regions with gray matter volume (GMV) and gray matter density (GMD) abnormalities in MDD patients with somatic symptoms had corresponding brain functional abnormalities.

RESULTS

Between depression with and without somatic symptoms, we found that there are extensive GMV and GMD differences involving cortical regions such as the temporal lobe, occipital lobe, and insula, as well as subcortical brain regions such as thalamus and striatum. The comparison results of weight DC signals of GMV and GMD abnormal clusters between the SD and NSD groups were basically consistent with the GMV and GMD abnormal clusters.

CONCLUSION

The results indicate that the structure and function of cortical-striatal-thalamic-cortical (CSTC) circuit centered on the thalamus were abnormal in MDD patients with somatic symptoms. This may be the neurobiological basis of somatic symptoms in MDD.

Amygdalar functional connectivity during resting and evoked pain in youth with functional abdominal pain disorders

ABSTRACT

Pediatric functional abdominal pain disorders (FAPD) are highly prevalent, difficult to diagnose, and challenging to treat. The brain systems supporting FAPD remain poorly understood. This investigation examined the neuromechanisms of FAPD during a well-tolerated visceral pain induction task, the water load symptom provocation task (WL-SPT). Youth between the ages of 11 and 17 years participated. Functional connectivity (FC) was examined through the blood oxygenation level-dependent effect using the left and right amygdala (AMY) as seed regions. Relationships of the time courses within these seeds with voxels across the whole brain were evaluated. Arterial spin labeling was used to assess regional brain activation by examining cerebral blood flow. Increased FC between the left AMY with regions associated with nociceptive processing (eg, thalamus) and right AMY FC changes with areas associated with cognitive functioning (dorsolateral prefrontal cortex) and the default mode network (DMN; parietal lobe) were observed in youth with FAPD after the WL-SPT. These changes were related to changes in pain unpleasantness. Amygdala FC changes post-WL-SPT were also related to changes in pain intensity. Amygdala FC with the DMN in youth with FAPD also differed from healthy controls. Global cerebral blood flow changes were also noted between FAPD and healthy controls, but no significant differences in grey matter were detected either between groups or during the WL-SPT in youth with FAPD. Findings confirm youth with FAPD undergo changes in brain systems that could support the development of biomarkers to enhance understanding of the mechanisms of pain and treatment response.

Altered Resting Brain Functions in Patients With Irritable Bowel Syndrome: A Systematic Review

Background

The neural activity of irritable bowel syndrome (IBS) patients in the resting state without any intervention has not been systematically studied. The purpose of this study was to compare the resting-state brain functions of IBS patients with healthy controls (HCs).

Methods

The published neuroimage studies were obtained from electronic databases including PubMed, EMBASE, PsycINFO, Web of Science Core, CNKI Database, Wanfang Database, VIP Database, and CBMdisc. Search dates were from inception to March 14th, 2022. The studies were identified by the preidentified inclusion and exclusion criteria. Two independent reviewers compiled the studies and evaluated them for quality and bias.

Results

Altogether 22 fMRI studies were included in this review. The risk of bias of the included studies was generally low. The findings indicated that in IBS patients, increased or decreased brain areas were mostly associated with visceral sensations, emotional processing, and pain processing. According to brain network research, IBS may exhibit anomalies in the DMN, CEN, and emotional arousal networks. The fluctuations in emotion (anxiety, sadness) and symptoms in IBS patients were associated with alterations in the relevant brain regions.

Conclusion

This study draws a preliminary conclusion that there are insufficient data to accurately distinguish the different neurological features of IBS in the resting state. Additional high-quality research undertaken by diverse geographic regions and teams is required to reach reliable results regarding resting-state changed brain regions in IBS.

Brain structural alterations in MDD patients with gastrointestinal symptoms: Evidence from the REST-meta-MDD project

OBJECTIVE

While gastrointestinal (GI) symptoms are very common in patients with major depressive disorder (MDD), few studies have investigated the neural basis behind these symptoms. In this study, we sought to elucidate the neural basis of GI symptoms in MDD patients by analyzing the changes in regional gray matter volume (GMV) and gray matter density (GMD) in brain structure.

METHOD

Subjects were recruited from 13 clinical centers and categorized into three groups, each of which is based on the presence or absence of GI symptoms: the GI symptoms group (MDD patients with at least one GI symptom), the non-GI symptoms group (MDD patients without any GI symptoms), and the healthy control group (HCs). Structural magnetic resonance images (MRI) were collected of 335 patients in the GI symptoms group, 149 patients in the non-GI symptoms group, and 446 patients in the healthy control group. The 17-item Hamilton Depression Rating Scale (HAMD-17) was administered to all patients. Correlation analysis and logistic regression analysis were used to determine if there was a correlation between the altered brain regions and the clinical symptoms.

RESULTS

There were significantly higher HAMD-17 scores in the GI symptoms group than that of the non-GI symptoms group (P < 0.001). Both GMV and GMD were significant different among the three groups for the bilateral superior temporal gyrus, bilateral middle temporal gyrus, left lingual gyrus, bilateral caudate nucleus, right Fusiform gyrus and bilateral Thalamus (GRF correction, cluster-P < 0.01, voxel-P < 0.001). Compared to the HC group, the GI symptoms group demonstrated increased GMV and GMD in the bilateral superior temporal gyrus, and the non-GI symptoms group demonstrated an increased GMV and GMD in the right superior temporal gyrus, right fusiform gyrus and decreased GMV in the right Caudate nucleus (GRF correction, cluster-P < 0.01, voxel-P < 0.001). Compared to the non-GI symptoms group, the GI symptoms group demonstrated significantly increased GMV and GMD in the bilateral thalamus, as well as decreased GMV in the bilateral superior temporal gyrus and bilateral insula lobe (GRF correction, cluster-P < 0.01, voxel-P < 0.001). While these changed brain areas had significantly association with GI symptoms (P < 0.001), they were not correlated with depressive symptoms (P > 0.05). Risk factors for gastrointestinal symptoms in MDD patients (p < 0.05) included age, increased GMD in the right thalamus, and decreased GMV in the bilateral superior temporal gyrus and left Insula lobe.

CONCLUSION

MDD patients with GI symptoms have more severe depressive symptoms. MDD patients with GI symptoms exhibited larger GMV and GMD in the bilateral thalamus, and smaller GMV in the bilateral superior temporal gyrus and bilateral insula lobe that were correlated with GI symptoms, and some of them and age may contribute to the presence of GI symptoms in MDD patients.

The Brain-Gut-Microbiome System: Pathways and Implications for Autism Spectrum Disorder

Gastrointestinal dysfunction is one of the most prevalent physiological symptoms of autism spectrum disorder (ASD). A growing body of largely preclinical research suggests that dysbiotic gut microbiota may modulate brain function and social behavior, yet little is known about the mechanisms that underlie these relationships and how they may influence the pathogenesis or severity of ASD. While various genetic and environmental risk factors have been implicated in ASD, this review aims to provide an overview of studies elucidating the mechanisms by which gut microbiota, associated metabolites, and the brain interact to influence behavior and ASD development, in at least a subgroup of individuals with gastrointestinal problems. Specifically, we review the brain-gut-microbiome system and discuss findings from current animal and human studies as they relate to social-behavioral and neurological impairments in ASD, microbiota-targeted therapies (i.e., probiotics, fecal microbiota transplantation) in ASD, and how microbiota may influence the brain at molecular, structural, and functional levels, with a particular interest in social and emotion-related brain networks. A deeper understanding of microbiome-brain-behavior interactions has the potential to inform new therapies aimed at modulating this system and alleviating both behavioral and physiological symptomatology in individuals with ASD.

Networks Are Associated With Acupuncture Treatment in Patients With Diarrhea-Predominant Irritable Bowel Syndrome: A Resting-State Imaging Study

Background: Irritable Bowel Syndrome (IBS), as a functional gastrointestinal disorder, is characterized by abdominal pain and distension. Recent studies have shown that acupuncture treatment improves symptoms of diarrhea-predominant irritable bowel syndrome (IBS-D) by altering networks in certain brain regions. However, few studies have used resting-state functional magnetic resonance imaging (fMRI) to compare altered resting-state inter-network functional connectivity in IBS-D patients before and after acupuncture treatment. Objective: To analyze altered resting-state inter-network functional connectivity in IBS-D patients before and after acupuncture treatment. Methods: A total of 74 patients with IBS-D and 31 healthy controls (HCs) were recruited for this study. fMRI examination was performed in patients with IBS-D before and after acupuncture treatment, but only at baseline in HCs. Data on the left frontoparietal network (LFPN), default mode network (DMN), salience network (SN), ventral attention network (VAN), auditory network (AN), visual network (VN), sensorimotor network (SMN), dorsal attention network (DAN), and right frontoparietal network (RFPN) were subjected to independent component analysis (ICA). The functional connectivity values of inter-network were explored. Results: Acupuncture decreased irritable bowel syndrome symptom severity score (IBS-SSS) and Hamilton Anxiety Scale (HAMA). It also ameliorated symptoms related to IBS-D. Notably, functional connectivity between AN and VAN, SMN and DMN, RFPN and VAN in IBS-D patients after acupuncture treatment was different from that in HCs. Furthermore, there were differences in functional connectivity between DMN and DAN, DAN and LFPN, DMN and VAN before and after acupuncture treatment. The inter-network changes in DMN-VAN were positively correlated with changes in HAMA, life influence degree, and IBS-SSS in IBS-D. Conclusion: Altered inter-network functional connectivity is involved in several important hubs in large-scale networks. These networks are altered by acupuncture stimulation in patients with IBS-D.

Inter-hemispheric Functional Connections Are More Vulnerable to Attack Than Structural Connection in Patients With Irritable Bowel Syndrome

Background/Aims

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disease characterized by recurrent abdominal pain and bowel dysfunction. However, the majority of previous neuroimaging studies focus on brain structure and connections but seldom on the inter-hemispheric connectivity or structural asymmetry. This study uses multi-modal imaging to investigate the abnormal changes across the 2 cerebral hemispheres in patients with IBS.

Methods

Structural MRI, resting-state functional MRI, and diffusion tensor imaging were acquired from 34 patients with IBS and 33 healthy controls. The voxel-mirrored homotopic connectivity, fractional anisotropy, fiber length, fiber number, and asymmetry index were calculated and assessed for group differences. In addition, we assessed their relevance for the severity of IBS.

Results

Compared with healthy controls, the inter-hemispheric functional connectivity of patients with IBS showed higher levels in bilateral superior occipital gyrus, middle occipital gyrus, precuneus, posterior cingulate gyrus, and angular gyrus, but lower in supplementary motor area. The statistical results showed no significant difference in inter-hemispheric anatomical connections and structural asymmetry, however negative correlations between inter-hemispheric connectivity and the severity of IBS were found in some regions with significant difference.

Conclusions

The functional connections between cerebral hemispheres were more susceptible to IBS than anatomical connections, and brain structure is relatively stable. Besides, the brain areas affected by IBS were concentrated in default mode network and sensorimotor network.

Cortical morphometry alterations in brain regions involved in emotional, motor-control and self-referential processing in patients with functional constipation

Functional constipation (FC) is a common functional gastrointestinal disorder (FGID). Neuroimaging studies on patients with FC showed brain functional abnormalities in regions involved in emotional process modulation, somatic and sensory processing and motor control. Brain structural imaging studies in patients with FGID have also shown disease-related alterations in cortical morphometry, but whether and how FC affects brain structure remains unclear. Structural Magnetic Resonance Imaging and surface-based morphometry analysis were used to investigate the impact of FC on cortical morphometry in 29 patients with FC and 29 healthy controls (HC). Results showed that patients with FC compared to HC had significantly decreased cortical thickness in the left middle frontal gyrus (MFG), dorsomedial (DMPFC) and ventromedial prefrontal gyrus (VMPFC), right dorsal anterior cingulate cortex (dACC), left orbitofrontal cortex (OFC), posterior cingulate cortex (PCC)/precuneus, middle temporal gyrus (MTG), and supplementary motor area (SMA) (P < 0.01). Correlation analysis showed that sensation of incomplete evacuation was negatively correlated with cortical thickness in the SMA (P < 0.0001). In addition, patients with FC also had decreased cortical volume than HC in the MTG, precentral gyrus (PreCen) and precuneus/cuneus (P < 0.01), as well as decreased cortical surface area in the PreCen (P < 0.01). No correlation was found between cortical volume/surface area and behavioral measures. These findings suggest that patients with FC are associated with cortical morphometric abnormalities in brain regions implicated in somatic/motor-control, emotional processing and self-referential processing.

Chronic pain in children: structural and resting-state functional brain imaging within a developmental perspective

Chronic pain is a major public health problem in the United States costing $635 billion annually. Hospitalizations for chronic pain in childhood have increased almost tenfold in the past decade, without breakthroughs in novel treatment strategies. Findings from brain imaging studies using structural and resting-state fMRI could potentially help personalize treatment to address this costly and prevalent health problem by identifying the underlying brain pathways that contribute, facilitate, and maintain chronic pain. The aim of this review is to synthesize structural and resting-state network pathology identified by recent brain imaging studies in pediatric chronic pain populations and discuss the potential impact of chronic pain on cortical development. Sex differences as well as treatment effects on these cortical alterations associated with symptom changes are also summarized. This area of research is still in its infancy with currently limited evidence available from a small number of studies, some of which suffer from limitations such as small sample size and suboptimal methodology. The identification of brain signatures of chronic pain in children may help to develop new pathways for future research as well as treatment strategies.

Paediatric functional abdominal pain disorders

Paediatric functional abdominal pain disorders, currently referred to as disorders of gut-brain interaction, comprise irritable bowel syndrome, functional dyspepsia, abdominal migraine and functional abdominal pain not otherwise specified, as defined by the Rome IV diagnostic criteria. Functional abdominal pain disorders are common disorders with a prevalence of 3-16% depending on country, age and sex. A greater understanding of aetiopathogenesis and pathophysiology is emerging and includes intestinal components (inflammation, motility and the microbiota), central factors (psychological aspects, sensitization and/or differences in connectivity or activity of certain brain regions) as well as extrinsic factors (infections). In particular, the timing of disruption of the microbiota-gut-brain axis seems to be important. Diagnosis is challenging but is primarily based on clinical symptoms and exclusion of other organic causes, with an emphasis on avoiding unnecessary invasive diagnostic procedures. The available pharmacological interventions are limited in children and, therefore, management has focused on combined approaches, including mind-targeted interventions (hypnotherapy and cognitive behavioural therapy), diet (probiotics) and percutaneous electrical nerve field stimulation. The evidence for their clinical efficacy, although limited, is favourable, with positive impacts on symptoms and overall quality of life. The coming decades hold promise for improved understanding and management of these enigmatic disorders.

Altered Brain Structure and Functional Connectivity and Its Relation to Pain Perception in Girls With Irritable Bowel Syndrome

OBJECTIVE

Imaging studies in adults with irritable bowel syndrome (IBS) have shown both morphological and resting state (RS) functional connectivity (FC) alterations related to cortical modulation of sensory processing. Because analogous differences have not been adequately investigated in children, this study compared gray matter volume (GMV) and RS-FC between girls with IBS and healthy controls (HC) and tested the correlation between brain metrics and laboratory-based pain thresholds (Pth).

METHODS

Girls with Rome III criteria IBS (n = 32) and matched HCs (n = 26) were recruited. In a subset of patients, Pth were determined using a thermode to the forearm. Structural and RS scans were acquired. A voxel-based general linear model, adjusting for age, was applied to compare differences between groups. Seeds were selected from regions with group GMV differences for a seed-to-voxel whole brain RS-FC analysis. Significance for analyses was considered at p < .05 after controlling for false discovery rate. Significant group differences were correlated with Pth.

RESULTS

Girls with IBS had lower GMV in the thalamus, caudate nucleus, nucleus accumbens, anterior midcingulate (aMCC), and dorsolateral prefrontal cortex. They also exhibited lower RS-FC between the aMCC and the precuneus, but greater connectivity between the caudate nucleus and precentral gyrus. Girls with IBS had higher Pth with a moderate effect size (t(22.81) = 1.63, p = .12, d = 0.64) and lower thalamic GMV bilaterally was correlated with higher Pth (left: r = -.62, p(FDR) = .008; right: r = -.51, p(FDR) = .08).

CONCLUSIONS

Girls with IBS had lower GMV in the PFC, basal ganglia, and aMCC, as well as altered FC between multiple brain networks, suggesting that structural changes related to IBS occur early in brain development. Girls with IBS also showed altered relationships between pain sensitivity and brain structure.

Sex Differences Linking Pain-Related Fear and Interoceptive Hypervigilance: Attentional Biases to Conditioned Threat and Safety Signals in a Visceral Pain Model

Although the broad role of fear and hypervigilance in conditions of the gut-brain axis like irritable bowel syndrome is supported by converging evidence, the underlying mechanisms remain incompletely understood. Even in healthy individuals, it remains unclear how pain-related fear may contribute to pain-related attentional biases for acute visceral pain. Building on our classical fear conditioning work in a clinically relevant model of visceral pain, we herein elucidated pain-related attentional biases shaped by associative learning in healthy women and men, aiming to elucidate possible sex differences and the role of psychological traits. To this end, we compared the impact of differentially conditioned pain-predictive cues on attentional biases in healthy women and men. Sixty-four volunteers accomplished a visual dot-probe task and subsequently underwent pain-related fear conditioning where one visual cue (CS⁺) was contingently paired with a painful rectal distention (US) while another cue remained unpaired (CS^-). During the following test phase, the dot-probe task was repeated to investigate changes in attentional biases in response to differentially valenced cues. While pain-related learning was comparable between groups, men revealed more pronounced attentional engagement with the CS⁺ and CS^- whereas women demonstrated stronger difficulties to disengage from the CS⁺ when presented with a neutral cue. However, when both CS⁺ and CS^- were presented together, women revealed stronger difficulties to disengage from the CS^-. Regression analyses revealed an interaction of sex, with negative affect predicting stronger avoidance of the CS⁺ and stronger difficulties to disengage attention from the CS^- in men. These results provide first evidence that pain-related fear conditioning may induce attentional biases differentially in healthy women and men. Hence, sex differences may play a role in attentional mechanisms underlying hypervigilance, and may be modulated by psychological vulnerability factors relevant to chronic visceral pain.

Interactions between gut permeability and brain structure and function in health and irritable bowel syndrome

Changes in brain-gut interactions have been implicated in the pathophysiology of chronic visceral pain in irritable bowel syndrome (IBS). Different mechanisms of sensitization of visceral afferent pathways may contribute to the chronic visceral pain reports and associated brain changes that characterize IBS. They include increased gut permeability and gut associated immune system activation, and an imbalance in descending pain inhibitory and facilitatory mechanisms. In order to study the involvement of these mechanisms, correlations between gut epithelial permeability and live bacterial passage, and structural and functional brain connectivity were measured in women with moderate-to-severe IBS and healthy women. The relationships between gut permeability and functional and anatomical connectivity were significantly altered in IBS compared with the healthy women. IBS participants with lower epithelial permeability reported increased IBS symptoms, which was associated with increased functional and structural connectivity in endogenous pain facilitation regions. The findings suggest that relationships between gut permeability and the brain are significantly altered in IBS and suggest the existence of IBS subtypes based on these interactions.

•

Brain-gut interactions are significantly altered in irritable bowel syndrome.

•

Brain-gut interactions engage pain modulation brain regions in healthy women.

•

Normal levels of gut permeability in IBS are linked with endogenous pain facilitation.

Microstructural White Matter Abnormalities in the Dorsal Cingulum of Adolescents with IBS

Alterations in fractional anisotropy (FA) have been considered to reflect microstructural white matter (WM) changes in disease conditions; however, no study to date has examined WM changes using diffusion tensor imaging (DTI) in adolescents with irritable bowel syndrome (IBS). The objective of the present study was two-fold: (1) to determine whether differences in FA, and other non-FA metrics, were present in adolescents with IBS compared to healthy controls using whole-brain, region of interest (ROI)-restricted tract-based spatial statistics (TBSS) and canonical ROI DTI analyses for the cingulum bundle, and (2) to determine whether these metrics were related to clinical measures of disease duration and pain intensity in the IBS group. A total of 16 adolescents with a Rome III diagnosis of IBS (females = 12; mean age = 16.29, age range: 11.96-18.5 years) and 16 age- and gender-matched healthy controls (females = 12; mean age = 16.24; age range: 11.71-20.32 years) participated in this study. Diffusion-weighted images were acquired using a Siemens 3-T Trio Tim Syngo MRI scanner with a 32-channel head coil. The ROI-restricted TBSS and canonical ROI-based DTI analyses revealed that adolescents with IBS showed decreased FA in the right dorsal cingulum bundle compared to controls. No relationship between FA and disease severity measures was found. Microstructural WM alterations in the right dorsal cingulum bundle in adolescents with IBS may reflect a premorbid brain state or the emergence of a disease-driven process that results from complex changes in pain- and affect-related processing via spinothalamic and corticolimbic pathways.

Disrupted functional connectivity density in irritable bowel syndrome patients

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder resulting from a dysregulation of the brain-gut axis. However, its exact neural substrate still remains unclear. This study investigated the changes of intrinsic whole brain functional connectivity pattern in IBS using functional connectivity density (FCD). We acquired resting-state functional magnetic resonance imaging (rs-fMRI) data from thirty-two IBS patients and thirty-two healthy controls. Functional connectivity density, a data-driven algorithm, was used to compute the long-range and short-range FCD values for each voxel in the brain of each subject, implying the amount of distant and local functional connections of cortical hubs. The FCD maps were compared between IBS patients and healthy controls. Pearson correlations analysis was also performed between abnormal FCD values and clinical/psychometric scores in patients. Compared to healthy controls, IBS patients showed concurrently decreased long- and short-range FCD in bilateral anterior midcingulate cortices (aMCC) and inferior parietal lobules (IPL), and decreased long-range FCD in right anterior insula, and decreased short-range FCD in bilateral prefrontal cortices, subgenual anterior cingulate cortices and caudates. IBS patients also had concurrently increased long- and short-range FCD mainly in primary sensorimotor cortices, as well as increased long-range FCD in right supplementary motor area and increased short-range FCD in occipital lobe. In addition, some regions with altered FCD showed abnormal functional connectivity in brain regions involved in pain matrix of IBS patients. Furthermore, the abnormal FCD values in right anterior insula and left caudate showed significant correlation with severity of symptoms and disease duration of IBS patients respectively. In conclusion, patients with IBS have widely disrupted FCD, which decreased in brain regions involved in homeostatic afferent network, emotional arouse, and cognitive regulation, while increased in regions associated with sensorimotor modulation. And the observed functional connectivity alterations unveiled complicated working patterns of pain matrix in IBS patients. This study may provide us with new insight into the underlying brain network topology of IBS.

Prospective Study of Gastrointestinal Symptoms in School Children of South America

OBJECTIVES

The aim of the study was to establish the prevalence of abdominal pain (AP) in school children in Pasto (Colombia) and determine the effect of AP on their daily activities; and compare the prevalence of AP and other gastrointestinal symptoms between school children from Pasto and Chicago.

METHODS

Fourth- and fifth-grade students from a public school and a private school in Colombia were invited to participate in a prospective study using the same methods and questionnaires (Spanish version) as a previous study conducted in Chicago schools. Children completed weekly confidential surveys for 8 consecutive weeks.

RESULTS

A total of 332 children participated in the study (40% girls, mean age 9.97 years, median 10, range 8-12 years): public school (288), private school (44). A total of 2425 surveys were analyzed. Out of 2656 possible weekly surveys (332 children × 8 weeks), 91.3% were completed. Overall weekly prevalence of gastrointestinal symptoms: AP (39%), nausea (29.5%), constipation (14%), diarrhea (10.5%), vomiting (9%). Children with AP reported interference with activities: gym (21.9%), school (17.3%), difficulty sleeping (13.7%), and social activities (12.6%). Out of all children, 8.4% sought medical attention for AP during the study period.

CONCLUSIONS

Gastrointestinal symptoms are common in school-aged children in Colombia and interfere with both daily activities and school attendance. The prevalence of AP, diarrhea, and vomiting found in the present study was similar to published prevalence of American children using similar methods.

Brain processing of rectal sensation in adolescents with functional defecation disorders and healthy controls

BACKGROUND

Decreased sensation of urge to defecate is often reported by children with functional constipation (FC) and functional nonretentive fecal incontinence (FNRFI). The aim of this cross-sectional study was to evaluate cerebral activity in response to rectal distension in adolescents with FC and FNRFI compared with healthy controls (HCs).

METHODS

We included 15 adolescents with FC, 10 adolescents with FNRFI, and 15 young adult HCs. Rectal barostat was performed prior to functional magnetic resonance imaging (fMRI) to determine individual pressure thresholds for urge sensation. Subjects received 2 sessions of 5 × 30 seconds of barostat stimulation during the acquisition of blood oxygenation level-dependent fMRI. Functional magnetic resonance imaging signal differences were analyzed using SPM8 in Matlab.

KEY RESULTS

Functional constipation and FNRFI patients had higher thresholds for urgency than HCs (P < .001). During rectal distension, FC patients showed activation in the anterior cingulate cortex, dorsolateral prefrontal cortex, inferior parietal lobule, and putamen. No activations were observed in controls and FNRFI patients. Functional nonretentive fecal incontinence patients showed deactivation in the hippocampus, parahippocampal gyrus, fusiform gyrus (FFG), lingual gyrus, posterior parietal cortex, and precentral gyrus. In HCs, deactivated areas were detected in the hippocampus, amygdala, FFG, insula, thalamus, precuneus, and primary somatosensory cortex. In contrast, no regions with significant deactivation were detected in FC patients.

CONCLUSIONS & INFERENCES

Children with FC differ from children with FNRFI and HCs with respect to patterns of cerebral activation and deactivation during rectal distension. Functional nonretentive fecal incontinence patients seem to resemble HCs when it comes to brain processing of rectal distension.

Reduced Functional Connectivity Between the Hypothalamus and High-order Cortical Regions in Adolescent Patients With Irritable Bowel Syndrome

The hypothalamus plays a critical role in maintaining visceral homeostasis. Altered hypothalamus activation has been implicated in functional gastrointestinal disorders, including irritable bowel syndrome (IBS). One important aspect of homeostatic regulation is the cortical modulation of limbic and paralimbic subsystems, including the hypothalamus, which in turn affects the descending regulatory processes mediating visceral homeostasis. Using neuroimaging, we evaluated hypothalamus functional connectivity in adolescent patients with IBS and age-matched healthy controls who received rectal distension stimulations. More extensive hypothalamus connectivity was observed in liminal than subliminal condition in controls, but not in patients with IBS. Compared with controls, patients with IBS showed significantly reduced hypothalamus connectivity in the bilateral prefrontal cortices, supplementary motor and premotor areas, bilateral sensorimotor cortex, and limbic subareas, which are specifically involved in homeostatic regulation. The findings support the generalized homeostatic regulation model that reduced cortical and limbic modulations of hypothalamus functioning underlies disrupted visceral homeostasis in patients with IBS.

Altered right anterior insular connectivity and loss of associated functions in adolescent chronic fatigue syndrome

Impairments in cognition, pain intolerance, and physical inactivity characterize adolescent chronic fatigue syndrome (CFS), yet little is known about its neurobiology. The right dorsal anterior insular (dAI) connectivity of the salience network provides a motivational context to stimuli. In this study, we examined regional functional connectivity (FC) patterns of the right dAI in adolescent CFS patients and healthy participants. Eighteen adolescent patients with CFS and 18 aged-matched healthy adolescent control participants underwent resting-state functional magnetic resonance imaging. The right dAI region of interest was examined in a seed-to-voxel resting-state FC analysis using SPM and CONN toolbox. Relative to healthy adolescents, CFS patients demonstrated reduced FC of the right dAI to the right posterior parietal cortex (PPC) node of the central executive network. The decreased FC of the right dAI–PPC might indicate impaired cognitive control development in adolescent CFS. Immature FC of the right dAI–PPC in patients also lacked associations with three known functional domains: cognition, pain and physical activity, which were observed in the healthy group. These results suggest a distinct biological signature of adolescent CFS and might represent a fundamental role of the dAI in motivated behavior.

Neurostimulation for abdominal pain-related functional gastrointestinal disorders in adolescents: a randomised, double-blind, sham-controlled trial

BACKGROUND

Development of safe and effective therapies for paediatric abdominal pain-related functional gastrointestinal disorders is needed. A non-invasive, US Food and Drug Administration-cleared device (Neuro-Stim, Innovative Health Solutions, IN, USA) delivers percutaneous electrical nerve field stimulation (PENFS) in the external ear to modulate central pain pathways. In this study, we evaluated the efficacy of PENFS in adolescents with abdominal pain-related functional gastrointestinal disorders.

METHODS

In this randomised, sham-controlled trial, we enrolled adolescents (aged 11-18 years) who met Rome III criteria for abdominal pain-related functional gastrointestinal disorders from a single US outpatient gastroenterology clinic. Patients were randomly assigned (1:1) with a computer-generated randomisation scheme to active treatment or sham (no electrical charge) for 4 weeks. Patients were stratified by sex and presence or absence of nausea. Allocation was concealed from participants, caregivers, and the research team. The primary efficacy endpoint was change in abdominal pain scores. We measured improvement in worst abdominal pain and composite pain score using the Pain Frequency-Severity-Duration (PFSD) scale. Participants with less than 1 week of data and those with organic disease identified after enrolment were excluded from the modified intention-to-treat population. This trial has been completed and is registered with ClinicalTrials.gov, number NCT02367729.

FINDINGS

Between June 18, 2015, and Nov 17, 2016, 115 children with abdominal pain-related functional gastrointestinal disorders were enrolled and assigned to either PENFS (n=60) with an active device or sham (n=55). After exclusion of patients who discontinued treatment (n=1 in the PENFS group; n=7 in the sham group) and those who were excluded after randomisation because they had organic disease (n=2 in the PENFS group; n=1 in the sham group), 57 patients in the PENFS group and 47 patients in the sham group were included in the primary analysis. Patients in the PENFS group had greater reduction in worst pain compared with sham after 3 weeks of treatment (PENFS: median score 5·0 [IQR 4·0-7·0]; sham: 7·0 [5·0-9·0]; least square means estimate of change in worse pain 2·15 [95% CI 1·37-2·93], p<0·0001). Effects were sustained for an extended period (median follow-up 9·2 weeks [IQR 6·4-13·4]) in the PENFS group: median 8·0 (IQR 7·0-9·0) at baseline to 6·0 (5·0-8·0) at follow-up versus sham: 7·5 (6·0-9·0) at baseline to 7·0 (5·0-8·0) at follow-up (p<0·0001). Median PFSD composite scores also decreased significantly in the PENFS group (from 24·5 [IQR 16·8-33.3] to 8·4 [3·2-16·2]) compared with sham (from 22·8 [IQR 8·4-38·2] to 15·2 [4·4-36·8]) with a mean decrease of 11·48 (95% CI 6·63-16·32; p<0·0001) after 3 weeks. These effects were sustained at extended follow-up in the PENFS group: median 24·5 (IQR 16·8-33·3) at baseline to 12 (3·6-22·5) at follow-up, compared with sham: 22·8 (8·4-38·2) at baseline to 16·8 (4·8-33·6) at follow-up (p=0·018). Ten patients reported side-effects (three of whom discontinued the study): ear discomfort (n=6; three in the PENFS group, three in the sham group), adhesive allergy (n=3; one in the PENFS group, two in the sham group), and syncope due to needle phobia (n=1; in the sham group). There were no serious adverse events.

INTERPRETATION

Our results show that PENFS with Neuro-Stim has sustained efficacy for abdominal pain-related functional gastrointestinal disorders in adolescents. This safe and effective approach expands treatment options and should be considered as a non-pharmacological alternative for these disorders.

FUNDING

American Neurogastroenterology and Motility Society.

How to Perform and Interpret Functional Magnetic Resonance Imaging Studies in Functional Gastrointestinal Disorders

Functional neuroimaging studies have revealed the importance of the role of cognitive and psychological factors and the dysregulation of the brain-gut axis in functional gastrointestinal disorder patients. Although only a small number of neuroimaging studies have been conducted in functional gastrointestinal disorder patients, and despite the fact that the neuroimaging technique requires a high level of knowledge, the technique still has a great deal of potential. The application of functional magnetic resonance imaging (fMRI) technique in functional gastrointestinal disorders should provide novel methods of diagnosing and treating patients. In this review, basic knowledge and technical/practical issues of fMRI will be introduced to clinicians.

The pediatric Rome IV criteria: what's new?

Functional gastrointestinal disorders (FGIDs) are common in children of all ages and comprise of a wide range of conditions related to the gastrointestinal tract that cannot be attributed to structural or biochemical abnormalities. FGIDs are diagnosed according to the symptom-based Rome criteria. Areas covered: In 2016, the revised pediatric Rome IV criteria were published, these revised criteria are discussed in this review article. For the youngest age group (neonates/toddlers), the criteria for infant colic have undergone the most notable revisions. The most prominent changes in Rome IV were made in the criteria for children/adolescents, with the definition of two new FGIDs (functional nausea and functional vomiting) and the restructuring of the criteria for functional abdominal pain disorders, including the definition of FGID subtypes for functional dyspepsia and irritable bowel syndrome. Expert commentary: Overall, the Rome IV have been refined and are expected to improve the process of diagnosing FGIDs in the pediatric population and to better facilitate the healthcare professional in distinguishing different clinical entities. These changes will likely benefit future research and clinical care.

Brain Lesions among Orally Fed and Gastrostomy-Fed Dysphagic Preterm Infants: Can Routine Qualitative or Volumetric Quantitative Magnetic Resonance Imaging Predict Feeding Outcomes?

INTRODUCTION

The usefulness of qualitative or quantitative volumetric magnetic resonance imaging (MRI) in early detection of brain structural changes and prediction of adverse outcomes in neonatal illnesses warrants further investigation. Our aim was to correlate certain brain injuries and the brain volume of feeding-related cortical and subcortical regions with feeding method at discharge among preterm dysphagic infants.

MATERIALS AND METHODS

Using a retrospective observational study design, we examined MRI data among 43 (22 male; born at 31.5 ± 0.8 week gestation) infants who went home on oral feeding or gastrostomy feeding (G-tube). MRI scans were segmented, and volumes of brainstem, cerebellum, cerebrum, basal ganglia, thalamus, and vermis were quantified, and correlations were made with discharge feeding outcomes. Chi-squared tests were used to evaluate MRI findings vs. feeding outcomes. ANCOVA was performed on the regression model to measure the association of maturity and brain volume between groups.

RESULTS

Out of 43 infants, 44% were oral-fed and 56% were G-tube fed at hospital discharge (but not at time of the study). There was no relationship between qualitative brain lesions and feeding outcomes. Volumetric analysis revealed that cerebellum was greater (p < 0.05) in G-tube fed infants, whereas cerebrum volume was greater (p < 0.05) in oral-fed infants. Other brain regions did not show volumetric differences between groups.

CONCLUSION

This study concludes that neither qualitative nor quantitative volumetric MRI findings correlate with feeding outcomes. Understanding the complexity of swallowing and feeding difficulties in infants warrants a comprehensive and in-depth functional neurological assessment.

Pilot Study of Functional Magnetic Resonance Imaging Responses to Somatic Pain Stimuli in Youth With Functional and Inflammatory Gastrointestinal Disease

BACKGROUND

Brain-gut axis signaling modifies gastrointestinal symptomatology. Altered neural processing of intestinal pain signals involves interoceptive brain regions in adults with functional and inflammatory gastrointestinal disorders. Although these disorders frequently present in childhood, there are no published studies in youth. We determined whether neural processing of somatic pain stimuli differs in adolescents and young adults (AYA) with irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), as compared to healthy controls (HC).

METHODS

IBS and IBD AYA (16-20 years) underwent anticipated and thermal pain stimuli of low and high intensity on their forearm and simultaneous blood oxygen level-dependent functional magnetic resonance imaging. Data from adult HC were used for comparison. Subjects answered surveys evaluating alexithymia, anxiety, depression, and pain catastrophizing. Group data were compared using linear mixed effects and analysis of variance.

RESULTS

Study groups were similar by sex but not age. Significant group by pain condition interactions were observed in interoceptive brain regions during pain anticipation, and within perceptual brain regions during perceived pain. Higher activation within interoceptive brain regions during anticipated pain was observed in IBS compared with IBD and HC subjects. IBD patients demonstrated increased activation in perceptual brain regions during experienced pain as compared to IBS and HC.

CONCLUSIONS

IBS and IBD AYA demonstrate altered neural processing of somatic pain compared with each other and with HC. Our results suggest that neuromodulatory interventions targeting interoceptive brain circuits in IBS and perceptual brain regions in IBD may be effective.

Approach to a Child with Functional Abdominal Pain

Functional abdominal pain (FAP) is one of the most common functional gastrointestinal disorders (FGIDs) of childhood. Only a minority of patients with FAP seek medical attention, often presenting to the primary care physician while symptoms are still evolving. The bio-psychosocial model of treatment not only aims to alleviate the illness symptoms but also identifies and remedies the psychological comorbidities and social factors that contribute to illness behavior. Many patients with a mild illness can be managed in the primary care setting. However those with chronic, severe, frequently relapsing, and disabling illness usually are referred to a pediatric gastroenterologist. One of the reason for referral is to exclude organic disorders such as peptic ulcer disease, celiac disease or inflammatory bowel disease which can present with chronic abdominal pain. Recent data suggest that psychological therapy is very effective in alleviating symptoms, a subset of patients may require dietary modification and medications as an adjunct to psychological treatment.

Urgency urinary incontinence and the interoceptive network: a functional magnetic resonance imaging study

BACKGROUND

Treatment of urgency urinary incontinence has focused on pharmacologically treating detrusor overactivity. Recent recognition that altered perception of internal stimuli (interoception) plays a role in urgency urinary incontinence suggests that exploration of abnormalities of brain function in this disorder could lead to better understanding of urgency incontinence and its treatment.

OBJECTIVE

We sought to: (1) evaluate the relationship between bladder filling, perceived urgency, and activation at brain sites within the interoceptive network in urgency urinary incontinence; (2) identify coactivation of other brain networks that could affect interoception during bladder filling in urgency incontinence; and (3) demonstrate interaction between these sites prior to bladder filling by evaluating their resting-state connectivity.

STUDY DESIGN

We performed an observational cohort study using functional magnetic resonance imaging to compare brain function in 53 women with urgency urinary incontinence and 20 controls. Whole-brain voxelwise analyses of covariance were performed to examine differences in functional brain activation between groups during a task consisting of bladder filling, hold (static volume), and withdrawal phases. The task was performed at 3 previously established levels of baseline bladder volume, the highest exceeding strong desire to void volume. All women continuously rated their urge on a 0- to 10-point Likert scale throughout the task and a mixed measures analysis of variance was used to test for differences in urge ratings. Empirically derived regions of interest from analysis of activation during the task were used as seeds for examining group differences in resting-state functional connectivity.

RESULTS

In both urgency urinary incontinent participants and controls, changes in urge ratings were greatest during bladder filling initiated from a high baseline bladder volume and urgency incontinent participants' rating changes were greater than controls. During this bladder-filling phase urgency incontinent participant's activation of the interoceptive network was greater than controls, including in the left insula and the anterior and middle cingulate cortex. Urgency incontinent participant's activation was also greater than controls at sites in the ventral attention network and posterior default mode network. Urgency incontinent participant's connectivity was greater than controls between a middle cingulate seed point and the dorsal attention network, a "top-down" attentional network. Control connectivity was greater between the midcingulate seed point and the ventral attention network, a "bottom-up" attentional network.

CONCLUSION

Increasing urge was associated with greater urgency incontinent participant than control activation of the interoceptive network and activation in networks that are determinants of self-awareness (default mode network) and of response to unexpected external stimuli (ventral attention network). Differences in connectivity between interoceptive networks and opposing attentional networks (ventral attention network vs dorsal attention network) were present even before bladder filling (in the resting state). These findings are strong evidence for a central nervous system component of urgency urinary incontinence that could be mediated by brain-directed therapies.

Abdominal Pain, the Adolescent and Altered Brain Structure and Function

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder of unknown etiology. Although relatively common in children, how this condition affects brain structure and function in a pediatric population remains unclear. Here, we investigate brain changes in adolescents with IBS and healthy controls. Imaging was performed with a Siemens 3 Tesla Trio Tim MRI scanner equipped with a 32-channel head coil. A high-resolution T1-weighted anatomical scan was acquired followed by a T2-weighted functional scan. We used a surface-based morphometric approach along with a seed-based resting-state functional connectivity (RS-FC) analysis to determine if groups differed in cortical thickness and whether areas showing structural differences also showed abnormal RS-FC patterns. Patients completed the Abdominal Pain Index and the GI Module of the Pediatric Quality of Life Inventory to assess abdominal pain severity and impact of GI symptoms on health-related quality of life (HRQOL). Disease duration and pain intensity were also assessed. Pediatric IBS patients, relative to controls, showed cortical thickening in the posterior cingulate (PCC), whereas cortical thinning in posterior parietal and prefrontal areas were found, including the dorsolateral prefrontal cortex (DLPFC). In patients, abdominal pain severity was related to cortical thickening in the intra-abdominal area of the primary somatosensory cortex (SI), whereas HRQOL was associated with insular cortical thinning. Disease severity measures correlated with cortical thickness in bilateral DLPFC and orbitofrontal cortex. Patients also showed reduced anti-correlations between PCC and DLPFC compared to controls, a finding that may reflect aberrant connectivity between default mode and cognitive control networks. We are the first to demonstrate concomitant structural and functional brain changes associated with abdominal pain severity, HRQOL related to GI-specific symptoms, and disease-specific measures in adolescents with IBS. It is possible such changes will be responsive to therapeutic intervention and may be useful as potential markers of disease progression or reversal.