Central nervous system involvement in functional gastrointestinal disorders

From Gut to Brain: Uncovering Potential Serum Biomarkers Connecting Inflammatory Bowel Diseases to Neurodegenerative Diseases

Inflammatory bowel diseases (IBDs) are characterized by chronic gastrointestinal inflammation due to abnormal immune responses to gut microflora. The gut-brain axis is disrupted in IBDs, leading to neurobiological imbalances and affective symptoms. Systemic inflammation in IBDs affects the brain's inflammatory response system, hormonal axis, and blood-brain barrier integrity, influencing the gut microbiota. This review aims to explore the association between dysregulations in the gut-brain axis, serum biomarkers, and the development of cognitive disorders. Studies suggest a potential association between IBDs and the development of neurodegeneration. The mechanisms include systemic inflammation, nutritional deficiency, GBA dysfunction, and the effect of genetics and comorbidities. The objective is to identify potential correlations and propose future research directions to understand the impact of altered microbiomes and intestinal barrier functions on neurodegeneration. Serum levels of vitamins, inflammatory and neuronal damage biomarkers, and neuronal growth factors have been investigated for their potential to predict the development of neurodegenerative diseases, but current results are inconclusive and require more studies.

Quality of Life and Its Psychosocial Predictors among Patients with Disorders of Gut-Brain Interaction: A Comparison with Age- and Sex-Matched Controls

The disorders of gut-brain interaction (DGBIs) are a heterogeneous group of chronic conditions that greatly reduce patients' quality of life (QoL). To date, biopsychosocial factors (such as gastrointestinal symptoms, alexithymia, and interpersonal problems) are believed to contribute to the development and maintenance of DGBIs, but their role in affecting patients' QoL is still under investigation. Out of 141 patients seeking treatment for their gastrointestinal symptoms, 71 were diagnosed with a DGBI (47 females, 66.2%; Mage: 41.49 ± 17.23 years) and were age- and sex-matched to 71 healthy controls (47 females, 66.2%; Mage: 40.45 ± 16.38 years) without any current gastrointestinal symptom or diagnosis. Participants completed a sociodemographic and clinical questionnaire and a survey investigating several psychosocial risk factors. We found greater symptom severity and difficulties in identifying feelings among patients compared to controls. Further, multiple linear regression analyses evidenced that, among patients, higher expressive suppression of emotions, difficulties in identifying feelings and interpersonal problems, and a lower cognitive reappraisal of emotions predicted lower QoL. Data suggest that the QoL of patients with DGBIs is affected not only by common risk factors (e.g., interpersonal problems) but also by specific difficulties in processing and regulating emotions. The implications of these findings are discussed.

Irritable bowel syndrome (IBS): could we decide what is behind?

Functional visceral problems are frequently present nowadays in the medical practice probably due to the significant mental and emotional load on people. Although physicians and psychophysiologists are active on the field, still we are far from a complete knowledge, despite the fact that scientists like the Hungarian Professor György Ádám already had initiated a new approach called visceral psychophysiology already a long time ago. In this article, we commemorate Professor Ádám by analyzing one of the most frequent functional disorders, irritable bowel syndrome (IBS), calling psychophysiology for help. First, we try to give a definition, then show the general descriptions and characteristics of IBS. Factors like stress, gender, and gastrointestinal pain are followed by the potential role of the immune system and the neuronal factors as well as the supposed brain mechanisms. We hope that this overview of the IBS-history would show how significant scientists can be decisive in certain fields of the science and practice.

Gastrointestinal Symptoms in Pediatric Patients with Anxiety Disorders and Their Relationship to Selective Serotonin Reuptake Inhibitor Treatment or Placebo

Gastrointestinal symptoms are commonly reported as adverse effects of selective serotonin reuptake inhibitors (SSRIs), the first-line pharmacologic treatment for pediatric anxiety disorders; however, the temporal course of these symptoms during treatment, although believed to be transient, has never been prospectively evaluated. Additionally, rates of gastrointestinal symptoms and functional gastrointestinal syndromes in anxious youth are poorly understood. We examined gastrointestinal symptoms in youth with anxiety disorders during a double-blind, placebo-controlled trial of escitalopram (n = 51). Then, in a separate sample of prospectively treated children and adolescents with generalized, social and/or separation anxiety disorders (n = 56), we examined the frequency of gastrointestinal symptoms based on the Questionnaire on Pediatric Gastrointestinal Symptoms (QPGS) and ROME III criteria and the association of these symptoms with clinical and demographic characteristics using logistic regression. The frequency/severity of abdominal pain, diarrhea, bloating constipation or total gastrointestinal symptoms did not differ between patients receiving placebo (n = 25) or escitalopram (n = 26). However, escitalopram-treated youth had transient changes in nausea/vomiting and total upper gastrointestinal symptoms during the first two weeks of treatment. ROME III criteria for functional gastrointestinal syndromes were present in 12/56 patients (21.4%). QPGS-related functional gastrointestinal syndromes and symptoms were unrelated to treatment, treatment type, or clinical or demographic variables. Gastrointestinal symptoms are common in youth with anxiety and SSRIs produce transient-rather than sustained-gastrointestinal symptoms. Assessing gastrointestinal symptoms prior to pharmacotherapy and discussing factors that increase (or decrease) the likelihood of transient SSRI-related symptoms in youth may decrease patient uncertainty related to side effects and decrease medication-related anxiety.

Esophageal secondary peristalsis following acid infusion and chemical clearance correlate with mucosal integrity and acid sensitivity in GERD patients

Background

Acid sensitivity can be altered in patients with gastroesophageal reflux disease (GERD). Secondary peristalsis helps clear gastro-esophageal refluxate and residual ingested food bolus.

Objectives

The aim of this study was to investigate the associations among acid sensitivity, esophageal mucosal integrity, chemical clearance, and secondary peristalsis before and after esophageal acid infusion.

Design

This was an investigator-initiated, prospective, cross-sectional study.

Methods

Adult reflux patients underwent high resolution manometry and 24 h impedance-pH monitoring off acid suppression to identify GERD phenotypes, including non-erosive reflux disease (NERD), reflux hypersensitivity (RH), and functional heartburn (FH). Secondary peristalsis was assessed using five rapid 20 mL air injections into the esophagus before and after infusion of hydrochloric acid (0.1 N) into the mid-esophagus. Conventional acid infusion parameters recorded included lag time, intensity rating, and sensitivity score. Chemical clearance was evaluated using the post-reflux swallow-induced peristaltic wave (PSPW), and mucosal integrity was assessed by the mean nocturnal baseline impedance (MNBI) derived from impedance-pH monitoring.

Results

A total of 88 patients (age 21-64 years, 62.5% women) completed the study including 12 patients with NERD, 45 with RH, and 31 with FH. There was no significant difference in acid infusion parameters between patients with NERD, RH, and FH. Upon acid infusion, patients who exhibited successful secondary peristalsis had longer lag time, higher MNBI, and shorter bolus contact time than those without secondary peristalsis. Meanwhile, patients with intact PSPW demonstrated significantly higher intensity ratings in response to acid perfusion and higher MNBI than those with impaired PSPW. The lag time correlated positively with MNBI (r = 0.285; p = 0.007).

Conclusion

In conclusion, the protective effect of esophageal secondary peristalsis and chemical clearance on esophageal mucosal integrity was demonstrated. Concerning acid sensitivity, longer lag time in patients with intact secondary peristalsis may be attributed to better esophageal mucosal integrity, while stronger intensity ratings may have a greater tendency to induce PSPW and protect esophageal mucosal integrity.

Application of Artificial Intelligence in Measuring Novel pH-Impedance Metrics for Optimal Diagnosis of GERD

Novel metrics extracted from pH-impedance monitoring can augment the diagnosis of gastroesophageal reflux disease (GERD). Artificial intelligence (AI) is being widely used to improve the diagnostic capabilities of various diseases. In this review, we update the current literature regarding applications of artificial intelligence in measuring novel pH-impedance metrics. AI demonstrates high performance in the measurement of impedance metrics, including numbers of reflux episodes and post-reflux swallow-induced peristaltic wave index and, furthermore, extracts baseline impedance from the entire pH-impedance study. AI is expected to play a reliable role in facilitating measuring novel impedance metrics in patients with GERD in the near future.

Gastroenterologist Primer: Endometriosis for Gastroenterologists

BACKGROUND AND AIM

A comprehensive understanding of endometriosis and its common gastrointestinal presentations are critical for gastroenterologists to ensure appropriate and timely screening and diagnosis. Endometriosis is a common inflammatory disease that frequently presents with gastrointestinal symptoms overlapping with irritable bowel syndrome (IBS) and other gastrointestinal disorders. Many endometriosis patients first present to a gastroenterologist or generalist, which may prolong the time to diagnosis and appropriate care.

METHOD AND RESULTS

This review describes the current literature on endometriosis presentation, overlap with gastrointestinal conditions, and standard diagnostic and treatment options for gastroenterologists to consider. For appropriate and swift treatment, gastroenterologists must consider an endometriosis diagnosis in females of menstruating age presenting with pain, bloating, altered stools, and non-gastrointestinal symptoms and refer patients for further evaluation.

A snapshot of eating behaviors in undergraduate college students living in South Florida

Objective: To examine a) whether college students' eating behaviors are different by students' sex and/or body mass index (BMI) categories and b) the correlations between college students' eating behaviors and the degree to which they rely on internal bodily signals for food intake. Participants: Undergraduate college students 18-24 years old at a public university located in South Florida. Methods: Eligible students answered questionnaires to examine interoception, intuitive eating, and eating behaviors including emotional eating, restrained eating, cognitive restraint, external eating, and uncontrolled eating. Pearson correlation and independent t test were used (significance: p < 0.05). Results: Females reported lower interoception, intuitive eating, and higher emotional eating than males. Students with lower BMI had higher intuitive eating and lower restrained eating. Interoception was positively correlated with intuitive eating and negatively correlated with emotional, uncontrolled, restrained, and external eating. Conclusion: College students who have a better connection with their bodily signals have healthier eating behaviors and lower BMI.

The complex involvement of the digestive tract in human defense behavior - structural and functional arguments

The digestive system has an innate monitoring and defense capacity, which allows the recognition and elimination of different dangerous substances. The complex analysis of the intestinal content comprises the cross-interactions between the epithelial cells, the enteroendocrine cells, the neural tissue and the cellular defense mechanisms. The enteric nervous system, also called "the enteric brain" or "the second brain" is the only neuronal network outside the central nervous system capable of autonomous reflex activity. The enteric nervous system activity is mostly independent of the central nervous system, but not in all aspects. In fact, even the enteral reflexes are a consequence of the bidirectional intestine-brain relation. The central nervous and enteric nervous systems are coupled through the sympathetic and parasympathetic branches of the autonomic nervous system. The gastrointestinal functions are regulated due to the interaction between the intrinsic neurons within the gastrointestinal wall and the extrinsic neurons outside the gastrointestinal tract. Here we provide an overview of the important role of the enteric brain in defensive behavior, as well as its structural and functional particularities that make it a special organ.

Effects of the Prolong Life With Nine Turn Method (Yan Nian Jiu Zhuan) Qigong on Brain Functional Changes in Patients With Chronic Fatigue Syndrome in Terms of Fatigue and Quality of Life

Background

Chronic fatigue syndrome (CFS) is characterized by persistent fatigue, which often leads to physical and psychological damage. The Prolong Life with Nine Turn method (PLWNT) Qigong is considered as one of the complementary treatments for improving symptoms in patients with CFS. In this study, we used functional magnetic resonance imaging (fMRI) to explore the effects of PLWNT intervention on the subjects with CFS.

Methods

Thirty four CFS patients were randomly divided into PLWNT group and cognitive behavioral therapy (CBT) group. Both groups were taught by a highly qualified professor at the Shanghai University of Traditional Chinese Medicine once a week and were supervised online during the remaining 6 days at home, over 12 consecutive weeks. We calculated the regional rs-fMRI index amplitude of low-frequency fluctuations (ALFF) for all subjects. To study the changes of the brain network, we used the brain regions with significant differences in ALFF as the regions of interest for whole-brain functional connectivity (FC) analysis. The Multi-dimensional Fatigue Inventory 20 (MFI-20) and Short Form 36-item Health Survey (SF-36) were used for clinical symptom assessment to explore the possible correlation between the rs-fMRI indicators and clinical variations.

Results

The ALFF values of the right superior frontal gyrus (SFG), and left median cingulate gyrus (DCG) were increased, whereas those of the left middle occipital gyrus (OG), right middle OG and left middle temporal gyrus (MTG) were decreased in PLWNT group. The FC values between the DCG and middle temporal gyrus (MTG), and those between the left OG and the right OG were enhanced. In addition, the SF-36 were positively with the left OG (r = 0.524), SFG (r = 0.517), and DCG (r = 0.533), MFI-20 were negatively with the SFG (r = −0.542) and DCG (r = −0.578). These results were all corrected by FWE (voxel level p &lt; 0.001, cluster level p &lt; 0.05).

Conclusion

CFS patients have abnormal regional spontaneous neuronal activity and abnormal functional connections between regions after PLWNT intervention. PLWNT can relieve the fatigue symptoms of CFS patients and improve their quality of life. The study was registered in the American Clinical Trial Registry (12/04/2018). Registration Number is NCT03496961.

Brain Neural Underpinnings of Interoception and Decision-Making in Alzheimer's Disease: A Narrative Review

This study reviews recent literature on interoception directing decision-making in Alzheimer's disease (AD). According to the somatic marker hypothesis, signals from the internal body direct decision-making and involve the ventromedial prefrontal cortex (vmPFC). After reviewing relevant studies, we summarize the brain areas related to interoception and decision-making (e.g., vmPFC, hippocampus, amygdala, hypothalamus, anterior cingulate cortex, and insular cortex) and their roles in and relationships with AD pathology. Moreover, we outline the relationship among interoception, the autonomic nervous system, endocrine system, and AD pathology. We discuss that impaired interoception leads to decreased decision-making ability in people with AD from the perspective of brain neural underpinning. Additionally, we emphasize that anosognosia or reduced self-awareness and metacognition in AD are remarkably congruent with the malfunction of the autonomic nervous system regulating the interoceptive network. Furthermore, we propose that impaired interoception may contribute to a loss in the decision-making ability of patients with AD. However, there still exist empirical challenges in confirming this proposal. First, there has been no standardization for measuring or improving interoception to enhance decision-making ability in patients with AD. Future studies are required to better understand how AD pathology induces impairments in interoception and decision-making.

Factors associated with the mental health status of isolated COVID-19 patients in Korea

Background

The COVID-19 pandemic has a substantial impact on the physical and mental health status of patients with COVID-19. This study's objective was to evaluate the factors associated with mental health in patients isolated with COVID-19.

Methods

It is a retrospective, cross-sectional study. One hundred and two patients discharged from COVID-19 hospitalization in Korea were analyzed. The primary outcome was the correlation between psychological problems such as anxiety, depression, and fear of stigma and physical symptoms such as respiratory symptoms, gastrointestinal symptoms, headache, and fever. Mental and physical symptoms were ascertained using closed and multiple-choice questions. The secondary outcome was the correlation between mental issues, demographic factors, and disease severity. Hypoxia and the need for oxygen therapy, a need for remdesivir antiviral treatment, and indications of pneumonia progression on chest x-ray were confirmed through a review of medical records and used to measure disease severity.

Results

Patients with COVID-19 indicated feelings of depression (48.1%), anxiety (49.1%), and fear of stigma (60.45%), and some continued to experience physical symptoms even after discharge. Logistic regression revealed that gastrointestinal symptoms positively correlated with depression (p < .05) and headache positively correlated with fear of stigma (p < .05), while the other factors were not statistically significant (p > .05).

Conclusions

This study showed that psychological symptoms persisted even after discharge. Gastrointestinal symptoms and headache were influential factors in predicting depression and fear of stigma. Based on this, dedicated COVID-19 hospitals should provide mental health support and preventive management.

Brain Functional Network and Amino Acid Metabolism Association in Females with Subclinical Depression

This study aimed to investigate the association between complex brain functional networks and the metabolites in urine in subclinical depression. Electroencephalography (EEG) signals were recorded from 78 female college students, including 40 with subclinical depression (ScD) and 38 healthy controls (HC). The phase delay index was utilized to construct functional connectivity networks and quantify the topological properties of brain networks using graph theory. Meanwhile, the urine of all participants was collected for non-targeted LC-MS metabolic analysis to screen differential metabolites. The global efficiency was significantly increased in the α-2, β-1, and β-2 bands, while the characteristic path length of β-1 and β-2 and the clustering coefficient of β-2 were decreased in the ScD group. The severity of depression was negatively correlated with the level of cortisone (p = 0.016, r = −0.40). The metabolic pathways, including phenylalanine metabolism, phenylalanine tyrosine tryptophan biosynthesis, and nitrogen metabolism, were disturbed in the ScD group. The three metabolic pathways were negatively correlated (p = 0.014, r = −0.493) with the global efficiency of the brain network of the β-2 band, whereas they were positively correlated (p = 0.014, r = 0.493) with the characteristic path length of the β-2 band. They were mainly associated with low levels of L-phenylalanine, and the highest correlation sparsity was 0.11. The disturbance of phenylalanine metabolism and the phenylalanine, tryptophan, tyrosine biosynthesis pathways cause depressive symptoms and changes in functional brain networks. The decrease in the L-phenylalanine level may be related to the randomization trend of the β-1 frequency brain functional network.

Abnormal interhemispheric functional connectivity in patients with primary dysmenorrhea: a resting-state functional MRI study

BACKGROUND

Neuroimaging studies have confirmed that functional connectivity (FC) disruption of pain-related brain networks may contribute to the cerebral pathophysiology of primary dysmenorrhea (PDM). However, it remains unclear whether FC of symmetrical regions of bilateral hemispheres associated with PDM is abnormal. This functional MRI study aimed to explore the changes of voxel-mirrored homotopic connectivity (VMHC) and seed-based FC in patients with PDM.

METHODS

A cohort comprising patients with PDM (n=35) and healthy controls (HCs) (n=41) underwent resting-state functional MRI scans during their menstrual phase. Interhemispheric FC was compared between the two groups using VMHC analysis. Brain areas with significant group differences in VMHC were selected as seed regions for FC analysis. Correlation analysis was also conducted to examine the relationship between abnormal connectivity of brain regions and clinical measures of pain and anxiety.

RESULTS

Compared with healthy individuals, patients with PDM showed significantly enhanced VMHC in the bilateral orbital part of the superior frontal gyrus and the bilateral middle frontal gyrus. Subsequent seed-based FC analysis showed enhanced connectivity between the aforementioned areas and pain-related brain structures. Hyperconnectivity between the left middle frontal gyrus and the right cingulate gyrus in patients was negatively correlated with an increase in the visual analogue score (VAS) for pain (r=-0.341, P<0.05).

CONCLUSIONS

Our findings indicate that ongoing dysmenorrhea is accompanied by abnormal interhemispheric functional coordination and enhanced connectivity in pain-related regions, attention networks, and the reward system. These findings may provide a novel perspective on the central mechanism of pain caused by PDM.

Pathophysiology of Pediatric Gastroesophageal Reflux Disease: Similarities and Differences With Adults

Gastroesophageal reflux (GOR) is defined as "the passage of gastric contents into the esophagus with or without regurgitation and vomiting" and gastroesophageal reflux disease (GORD) is defined "when GOR leads to troublesome symptoms affecting the daily functioning and/or complications." This definition was first developed in 2006 by the Montreal consensus group (1) and later on adopted by pediatric gastroenterology societies such as ESPGHAN and NASPGHAN in 2009 (2). The definition of gastroesophageal reflux reveals little about its pathophysiology and is focused on symptomatology. In this way, it acts as an umbrella term for the multifactorial causes of the disease and the various phenotypes encountered; from functional heartburn to hypersensitive esophagus and nonerosive reflux disease, to erosive esophagitis and Barrett's esophagus. This article is devoted to the pathophysiology of pediatric GORD in comparison to adult GORD and is divided in 2 parts. In the first part, we will systematically describe the different mechanisms for the generation and clearance of reflux events, while on the second part we will discuss the mechanisms involved in symptoms generation. Finally, we will discuss the similarities and differences between pediatric and adult GORD.

Potential Mechanisms of Acupuncture for Functional Dyspepsia Based on Pathophysiology

Functional dyspepsia (FD), a common disorder of gastrointestinal function, originated from the gastroduodenum. Although the therapeutic effect of acupuncture has been investigated by various high-quality randomized controlled trials, the potential mechanisms showed obvious heterogeneity. This review summarized the potential mechanisms of acupuncture on FD in order to guide for future laboratory and clinical studies. Here, we argued that the primary cause of FD was gastroduodenal low-grade inflammation and acid exposure, which impaired mucosal integrity, caused brain-gut axis dysfunction, and impaired brain network connectivity, all of which generated various symptom patterns. Overall the clinical studies indicated that acupuncture was a promising treatment to alleviate symptoms in FD patients, whose efficacy was influenced by acupoints and individual variance. Mechanistically, studies with animal models of FD and patients have shown that acupuncture, a non-invasive strategy for nerve stimulation, may have the potential to control intestinal inflammation and suppress acid-secretion via different somatic autonomic reflex pathways, regulate the brain-gut axis through intestinal microbiota, and has the potential to ameliorate FD-symptoms. The cumulative evidence demonstrated that acupuncture is a promising treatment to alleviate symptoms of FD patients.

Gastric neurons in the nucleus tractus solitarius are selective to the orientation of gastric electrical stimulation

Objective.Gastric electrical stimulation (GES) is a bioelectric intervention for gastroparesis, obesity, and other functional gastrointestinal disorders. In a potential mechanism of action, GES activates the nerve endings of vagal afferent neurons and induces the vago-vagal reflex through the nucleus tractus solitarius (NTS) in the brainstem. However, it is unclear where and how to stimulate in order to optimize the vagal afferent responses.Approach.To address this question with electrophysiology in rats, we applied mild electrical currents to two serosal targets on the distal forestomach with dense distributions of vagal intramuscular arrays (IMAs) that innervated the circular and longitudinal smooth muscle layers. During stimulation, we recorded single and multi-unit responses from gastric neurons in NTS and evaluated how the recorded responses depended on the stimulus orientation and amplitude.Main results.We found that NTS responses were highly selective to the stimulus orientation for a range of stimulus amplitudes. The strongest responses were observed when the applied current flowed in the same direction as the IMAs in parallel with the underlying smooth muscle fibers. Our results suggest that gastric neurons in NTS may encode the orientation-specific activity of gastric smooth muscles relayed by vagal afferent neurons.Significance.This finding suggests that the orientation of GES is critical to effective engagement of vagal afferents and should be considered in light of the structural phenotypes of vagal terminals in the stomach.

Oesophageal hypervigilance and visceral anxiety relate to reflux symptom severity and psychological distress but not to acid reflux parameters

BACKGROUND

The pathogenesis of gastro-oesophageal reflux disease (GERD) is complex and multifactorial. The oesophageal hypervigilance and anxiety scale (EHAS) is a novel cognitive-affective evaluation of visceral sensitivity.

AIMS

To investigate the interrelationship between EHAS and reflux symptom severity, psychological stress, acid reflux burden, phenotypes, and oesophageal mucosal integrity in patients with GERD.

METHODS

Patients with chronic reflux symptoms and negative endoscopy underwent 24-hour impedance-pH monitoring for phenotyping, acid reflux burden, and mucosal integrity with mean nocturnal baseline impedance (MNBI) calculation. Validated scores for patient-reported outcomes, including EHAS, GERD questionnaire (GERDQ), State-Trait Anxiety Inventory score, and Taiwanese Depression Questionnaire score, were recorded.

RESULTS

We enrolled 105 patients, aged 21-64 years (mean, 48.8), of whom 58.1% were female; 27 had non-erosive reflux disease, 43 had reflux hypersensitivity and 35 had functional heartburn. There were no significant differences in sex, EHAS, GERDQ, questionnaires of depression or anxiety among GERD phenotypes. EHAS was significantly correlated with GERDQ, questionnaires of depression and anxiety (P < 0.05). However, there were no significant correlations between GERDQ and questionnaires of depression or anxiety. Regarding patient-reported outcomes, GERDQ positively correlated with acid exposure time and negatively correlated with MNBI (P < 0.05).

CONCLUSIONS

EHAS associates with reflux symptom severity and psychological stress but not with acid reflux burden or mucosal integrity. Thus, EHAS assessment shows promise in assessment of subjective patient outcome and satisfaction with treatment, a hitherto unmet clinical need.

Esophageal afferent innervation and its role in gastro-esophageal reflux disease symptoms

PURPOSE OF REVIEW

Despite the wide prevalence of gastro-esophageal reflux disease (GERD), the neurophysiological mechanisms underlying heartburn perception in the esophagus of patients with GERD remains incompletely understood. Recent studies have highlighted the potential influence sensory afferent nerves innervating the oesophageal epithelium may have on heartburn pathogenesis. The purpose of this review is to consider the current understanding of esophageal afferent neuronal innervation, including the nociceptive role of acid-sensing receptors expressed on these sensory nerves, in relation to pain perception in the esophagus of GERD patients.

RECENT FINDINGS

Central and peripheral pathways of sensitization following noxious stimulation of nociceptive receptors expressed on afferent nerves can regulate the strength of sensory nerve activation in the esophagus, which can result in the amplification or suppression of afferent signal transmission. The localization and characterization of mucosal sensory afferent nerves vary between GERD phenotypes and may explain the heterogeneity of symptom perception in patients with apparently similar levels of reflux.

SUMMARY

In this review, we discuss the relevance of afferent esophageal innervation in heartburn perception, with a particular focus on the pathways of reflux-induced activation of nociceptive nerves.

The enteric nervous system in gastrointestinal disease etiology

A highly conserved but convoluted network of neurons and glial cells, the enteric nervous system (ENS), is positioned along the wall of the gut to coordinate digestive processes and gastrointestinal homeostasis. Because ENS components are in charge of the autonomous regulation of gut function, it is inevitable that their dysfunction is central to the pathophysiology and symptom generation of gastrointestinal disease. While for neurodevelopmental disorders such as Hirschsprung, ENS pathogenesis appears to be clear-cut, the role for impaired ENS activity in the etiology of other gastrointestinal disorders is less established and is often deemed secondary to other insults like intestinal inflammation. However, mounting experimental evidence in recent years indicates that gastrointestinal homeostasis hinges on multifaceted connections between the ENS, and other cellular networks such as the intestinal epithelium, the immune system, and the intestinal microbiome. Derangement of these interactions could underlie gastrointestinal disease onset and elicit variable degrees of abnormal gut function, pinpointing, perhaps unexpectedly, the ENS as a diligent participant in idiopathic but also in inflammatory and cancerous diseases of the gut. In this review, we discuss the latest evidence on the role of the ENS in the pathogenesis of enteric neuropathies, disorders of gut-brain interaction, inflammatory bowel diseases, and colorectal cancer.

Abnormalities in the thalamo-cortical network in patients with functional constipation

Functional constipation (FCon) is a common functional gastrointestinal disorder (FGID); neuroimaging studies have shown brain functional abnormalities in thalamo-cortical regions in patients with FGID. However, association between FCon and topological characteristics of brain networks remains largely unknown. We employed resting-state functional magnetic resonance imaging (RS-fMRI) and graph theory approach to investigate functional brain topological organization in 42 patients with FCon and 41 healthy controls (HC) from perspectives of global, regional and modular levels. Results showed patients with FCon had a significantly lower normalized clustering coefficient and small-worldness, implying decreased brain functional connectivity. Regions showed altered nodal degree and efficiency mainly located in the thalamus, rostral anterior cingulate cortex (rACC), and supplementary motor area (SMA), which are involved in somatic/sensory, emotional processing and motor-control. For the modular analysis, thalamus, rACC and SMA had an aberrant within-module nodal degree and nodal efficiency, and thalamus-related network exhibited abnormal interaction with the limbic network (amygdala and hippocampal gyrus). Nodal degree in the thalamus was negatively correlated with difficulty of defecation, and nodal degree in the rACC was negatively correlated with sensation of incomplete evacuation. These findings indicated that FCon was associated with abnormalities in the thalamo-cortical network.

Differences in dietary habits of people with vs without irritable bowel syndrome and their association with symptom and psychological status: A pilot study

BACKGROUND

Previous studies have demonstrated that dietary factors are involved in irritable bowel syndrome (IBS), but the role of diet was evaluated mostly based on food frequency questionnaire. Whether food categories, quantity per time, and intake frequency are different between IBS patients and non-IBS individuals has not been clearly clarified.

AIM

To explore differences in dietary habits of people with vs without IBS and their correlation with symptom and psychological status.

METHODS

A total of 220 questionnaires were administered in a community population and the Rome IV criteria was applied to diagnose IBS. The dietary questionnaire used in this study was multidimensional from food categories, quantity per time, and intake frequency, in contrast to "yes or no" classification used in previous studies. Questionnaires including IBS symptom severity scale (IBS-SSS), IBS quality of life, visceral sensitivity index, hospital anxiety and depression score (HADS), and gastrointestinal symptom rating scale were used to assess the participants. Rank sum test was used to compare the quantity per time and intake frequency between IBS patients and non-IBS participants. The correlation between psychological factors and diet was evaluated by Spearman correlation analysis. Logistic regression analysis was used to assess the possible dietary risk factors for IBS.

RESULTS

In total, 203 valid questionnaires were collected (response rate 92.3%). Twenty-five participants met the Rome IV criteria for IBS, including 15 (60.0%) women and 10 (40.0%) men. Compared with the non-IBS group, the quantity per time and intake frequency of soybean and its products, spicy food, and dry-fried nuts were statistically significant in IBS participants (P < 0.05). They were positively associated with IBS-SSS and HADS anxiety and depression scores (P < 0.05). Besides, seafood, soft drinks, vegetables, and fruits differed only in quantity per time. The intake frequencies of egg, barbecue, and coarse grain were statistically significant in IBS patients (P < 0.05). We also found that the frequency of soybean and its products (≥ 7 times/week, odds ratio = 11.613, 95% confidence interval: 2.145-62.855, P = 0.004) was an independent risk factor for IBS.

CONCLUSION

Both quantity per time and intake frequency, especially soybean, differ between IBS patients and non-IBS participants. Dietary habits might play potential roles in the pathophysiology of IBS.

Identification of Different Phenotypes of Esophageal Reflux Hypersensitivity and Implications for Treatment

BACKGROUND & AIMS

Reflux hypersensitivity (RH), a functional esophageal disorder, is detected in 14%-20% of patients who present with typical esophageal symptoms. As many as 40% of patients with RH do not respond to treatment with pain modulators or proton pump inhibitors (PPIs); behavior disorders might contribute to lack of treatment efficacy. We aimed to assess the prevalence of behavioral disorders and their effects on typical reflux symptoms in patients with RH.

METHODS

We performed a retrospective study of 542 patients with PPI-refractory esophageal symptoms (heartburn, regurgitation, or chest pain) or with symptoms that responded to PPI therapy, evaluated for anti-reflux surgery from January 2016 through August 2019 at a single center in London, United Kingdom. We collected data on symptoms, motility, and impedance-pH monitoring and assigned patients to categories of RH (n = 116), functional heartburn (n = 126), or non-erosive reflux disease (n = 300).

RESULTS

Of the 116 patients with a diagnosis of RH, 59 had only hypersensitivity, whereas 57 patients (49.2%) had either excessive supragastric belching (SGB, 39.7%), based on 24-hour impedance-pH monitoring, or rumination (9.5%), based on postprandial manometry combined with impedance. The prevalence of SGB and rumination in patients with RH was significantly higher than in patients with functional heartburn (22%; P < .001). Patients with RH and rumination were significantly younger (P = .005) and had the largest number of non-acid reflux episodes (P = .023). In patients with RH with SGB, SGB episodes were associated with 40.6% of marked reflux symptoms (heartburn, regurgitation, or chest pain), based on impedance-pH monitoring. In patients with RH and rumination, 40% of reflux-related symptoms (mostly regurgitation) were due to possible rumination episodes.

CONCLUSIONS

Almost half of patients with a diagnosis of RH have behavior disorders, including excessive SGB or rumination. Episodes of SGB or rumination are associated with typical reflux symptoms. Segregation of patients with diagnosis of RH into those with vs without behavioral disorders might have important therapeutic implications.

Association between gastrointestinal symptoms and depression among older adults in Taiwan: A cross-sectional study

BACKGROUND

Older adults with depression more frequently experience somatic and gastrointestinal (GI) problems compared with people without depression and younger adults with depression. However, whether GI symptoms are predictive of elevated rates of depression among older adults is unclear.

METHODS

We enrolled 106 older adults (>60 years old); 69 had late-life depression (LLD), and 37 were controls. All participants gave ratings on the Gastrointestinal Symptom Rating Scale (GSRS) and Hamilton Depression Rating Scale. Food consumption was assessed using a food frequency questionnaire, and a Mediterranean diet score was used as a covariate.

RESULTS

Compared with the controls, patients with LLD reported higher levels of depressive and GI symptoms and reported more reflux, abdominal pain, and dyspepsia symptoms, and these symptoms were correlated with Hamilton Depression Rating Scale scores (GSRS total: β = 0.47; reflux: β = 1.47; abdominal pain: β = 1.98; dyspepsia: β = 1.02; all p < 0.01). After demographic variables and Mediterranean diet score were controlled for, a logistic regression analysis indicated that total GSRS score was an independent determinant of LLD (odds ratio: 1.20, 95% CI: 1.04-1.38). Moreover, a stratified analysis by depression severity indicated that higher total GSRS score may contribute to greater depression severity (odds ratio: 1.25, 95% CI: 1.04-1.52).

CONCLUSION

We provide evidence that GI symptoms are associated with depressive symptoms among patients with LLD. Older people with more specific GI symptoms, such as reflux, abdominal pain, and dyspepsia, are potentially at greater risk of having LLD.

Gastric Motor Functions in Patients With Mood Disorders and Functional Gastroduodenal Symptoms

OBJECTIVE

Functional gastroduodenal symptoms (FGDSs) may result from perturbations in gastric emptying (GE) and gastric accommodation (GA), which are variably affected by acute stress. This study aimed to examine whether individuals who have both mood disorder and FGDS exhibit differences in GE and GA using standardized, validated, and reproducible noninvasive methods.

METHODS

Using a data retrieval program, 1554 individuals at a single center were identified after having undergone measurements of GE by scintigraphy of a 99mTc-radiolabeled egg (320 kcal, 30% fat meal) and GA by single-photon emission computed tomography to assess the underlying pathophysiology in FGDS. An extensive medical record review identified 267 of these individuals as having diagnoses of depression, anxiety, or comorbid anxiety/depression (CAD). Differences in GE and GA as related to the presence of anxiety or depressive disorders were analyzed using one-way analysis of variance on ranks and Mann-Whitney tests for the two-group comparisons.

RESULTS

Sixty-three patients with anxiety, 134 with depression, and 70 with CAD were identified. GE at 1 hour was slower (p = .04) and GE at 2 hours numerically decreased (p = .07) for depression compared with anxiety. GA was diminished for CAD compared with anxiety (p = .04) and depression (p = .009). There were no differences in fasting gastric volume or GE at 4 hours.

CONCLUSIONS

In this study examining GE and GA in anxiety and depressive disorders among patients with FGDS, the combined presence of anxiety and depression was associated with impaired GA compared with patients with depression or anxiety alone, and early GE seemed to be slower in those with depression compared with patients with anxiety.

Electroacupuncture intervention of visceral hypersensitivity is involved in PAR-2-activation and CGRP-release in the spinal cord

Electroacupuncture (EA) relieves visceral hypersensitivity (VH) with underlying inflammatory bowel diseases. However, the mechanism by which EA treats ileitis-induced VH is not clearly known. To assess the effects of EA on ileitis-induced VH and confirm whether EA attenuates VH through spinal PAR-2 activation and CGRP release, goats received an injection of 2,4,6-trinitro-benzenesulfonic-acid (TNBS) solution into the ileal wall. TNBS-injected goats were allocated into VH, Sham acupuncture (Sham-A) and EA groups, while goats treated with saline instead of TNBS solution were used as the control. Goats in EA group received EA at bilateral Hou-San-Li acupoints for 0.5 h at 7 days and thereafter repeated every 3 days for 6 times. Goats in the Sham-A group were inserted with needles for 0.5 h at the aforementioned acupoints without any hand manipulation and electric stimulation. Visceromotor responses to colorectal distension, an indicator of VH, were recorded by electromyography. The terminal ileum and thoracic spinal cord (T₁₁) were sampled for evaluating ileitis at days 7 and 22, and distribution and expression-levels of PAR-2, CGRP and c-Fos on day 22. TNBS-treated-goats exhibited apparent transmural-ileitis on day 7, microscopically low-grade ileitis on day 22 and VH at days 7–22. Goats of Sham-A, VH or EA group showed higher (P < 0.01) VH at days 7–22 than the Control-goats. EA-treated goats exhibited lower (P < 0.01) VH as compared with Sham-A or VH group. Immunoreactive-cells and expression-levels of spinal PAR-2, CGRP and c-Fos in the EA group were greater (P < 0.01) than those in the Control group, but less (P < 0.01) than those in Sham-A and VH groups on day 22. Downregulation of spinal PAR-2 and CGRP levels by EA attenuates the ileitis and resultant VH.

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

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

Imaging of Morphological Background in Selected Functional and Inflammatory Gastrointestinal Diseases in fMRI

The study focuses on evaluation of the Default Mode Network (DMN) activity in functional magnetic resonance imaging (fMRI) in resting state in patients with functional dyspepsia (FD) and irritable bowel syndrome (IBS), Crohn's disease and colitis ulcerosa (IBD) in comparison to healthy volunteers. We assume that etiology of both functional and non-specific inflammatory bowel diseases is correlated with disrupted structure of axonal connections. We would like to identify the network of neuronal connections responsible for presentation of symptoms in these diseases. 56 patients (functional dyspepsia, 18; Crohn's disease and colitis ulcerosa, 18; irritable bowel syndrome, 20) and 18 healthy volunteers underwent examination in MRI of the brain with assessment of brain morphology and central nervous system activity in functional imaging in resting state performed in 3T scanner. Compared to healthy controls' DMN in patients with non-specific digestive tract diseases comprised additional areas in superior frontal gyrus of left hemisphere, in left cingulum and in the left supplementary motor area. Discovered differences in the DMNs can be interpreted as altered processing of homeostatic stimuli. Our study group involved patients suffering from both functional and non-specific inflammatory bowel diseases. Nevertheless a spectrum of changes in the study group (superior frontal gyrus of the left hemisphere, in the left cingulum and in the left supplementary motor area) we were able to find common features, differentiating the whole study group from the healthy controls.

Stress-induced modulation of vagal afferents

Vagally dependent gastric functions, including motility, tone, compliance, and emptying rate, play an important role in the regulation of food intake and satiation. Vagal afferent fibers relay sensory information from the stomach, including meal-related information, centrally and initiate co-ordinated autonomic efferent responses that regulate upper gastrointestinal responses. The purpose of this mini-review is to highlight several recent studies which have uncovered the remarkable degree of neuroplasticity within gastric mechanosensitive vagal afferents and the recent study by Li et al, in this issue of Neurogastroenterology and Motility, who show that the mechanosensitivity of gastric vagal afferents is dysregulated in a murine model of chronic stress. The authors demonstrate that both gastric mucosal and tension afferents are hypersensitive following chronic stress, and responses to mucosal stroking and muscle stretch are enhanced significantly. As gastric distension and volumetric signaling is important in satiety signaling and meal termination, this may provide a mechanistic basis for the gastric hypersensitivity associated with stress-associated clinical problems such as functional dyspepsia.

Use of functional magnetic resonance imaging in patients with irritable bowel syndrome and functional dyspepsia

Functional brain imaging (positron emission tomography – PET, functional magnetic resonance imaging – fMRI), allowing in vivo analysis of the brain-digestive tract interaction and the neurological mechanisms underlying visceral hypersensitivity, significantly advanced research and helped in the understanding of the interrelations in this field. Differences in this parameter can result from alterations in task-related cognitive states or from resting state processes. Nowadays, advanced imaging techniques such as fMRI are more frequently used and are acknowledged among both clinicians and radiologists in the diagnostic algorithm of digestive tract diseases. Functional dyspepsia is a condition in which neuroimaging allows for analysis of dysfunctions within the brain-gut axis (BGA) engaged in processing of visceral discomfort and pain. The results of studies in patient groups with irritable bowel syndrome prove that psychosocial factors significantly affect the mechanisms regulating visceral sensitivity within the brain. The BGA includes neuronal pathways (autonomic nervous system), neuroendocrine (hypothalamo-pituitary-adrenal axis), and neuroimmunological ones. Psychological processes affect the functioning of the digestive system and can cause dyspeptic symptoms. A patient’s mental condition associated with stress can affect processes taking place in the central nervous system and trigger somatic reactions in the digestive tract through the autonomic visceral system.

Postprandial distress syndrome: stratification and management

Functional dyspepsia (FD), defined by the Rome consensus as the presence of functional symptoms originating from the gastroduodenum, is one of the most common functional gastrointestinal disorders. FD is subdivided into postprandial distress syndrome (PDS), with meal-related symptoms such as postprandial fullness and early satiation, and epigastric pain syndrome (EPS), with meal-unrelated symptoms such as epigastric pain or burning. We used a literature search for a narrative review on the current state of knowledge regarding PDS. Areas covered: Epidemiological studies support PDS as a separate entity and the biggest FD subgroup. The pathophysiology of PDS is heterogeneous, and disorders of gastric sensorimotor function as well as low grade duodenal inflammation have been implicated. Although prokinetic agents may provide the most pathophysiology-oriented treatment option, there is a paucity of suitable agents, and proton pump inhibitors are the traditional first-line therapy. Other options include agents that enhance gastric accommodation, such as acotiamide and 5-HT_1A agonists, neuromodulators such as mirtazapine, and traditional medicine approaches. Expert commentary: PDS is highly prevalent, with probably heterogeneous underlying pathophysiology. Motility modifying agents and neuromodulators are the cornerstone of PDS therapy, but there is a need for high quality studies of new therapeutic approaches.

Effect of the soft-tissue techniques in the quality of life in patients with Crohn's disease: A randomized controlled trial

BACKGROUND

Crohn's disease (CD) is a highly prevalent inflammatory bowel disease (IBD), characterized by recurring flares altered by periods of inactive disease and remission, affecting physical and psychological aspects and quality of life (QoL). The aim of this study was to determine the therapeutic benefits of soft non-manipulative osteopathic techniques in patients with CD.

METHODS

A single-blind randomized controlled trial was performed. 30 individuals with CD were divided into 2 groups: 16 in the experimental group (EG) and 14 in the control group (CG). The intervention period lasted 30 days (1 session every 10 days). Pain, global quality of life (GQoL) and QoL specific for CD (QoLCD) were assessed before and after the intervention. Anxiety and depression levels were measured at the beginning of the study.

RESULTS

We observed a significant effect of the treatment in both the physical and task subscales of the GQoL (P = .01 and P = .04, respectively) and also in the QoLCD (P ≤.0001) but not in pain score (P = .28). When the intensity of pain was taken into consideration in the analysis of the EG, there was a significantly greater increment in the QoLCD after treatment in people without pain than in those with pain (P = .02) The improvements in GQoL were independent from the disease status (P = .16).

CONCLUSIONS

Soft, non-manipulative osteopathic treatment is effective in improving overall and physical-related QoL in CD patients, regardless of the phase of the disease. Pain is an important factor that inversely correlates with the improvements in QoL.

Gastroesophageal reflux disease, functional dyspepsia and irritable bowel syndrome: common overlapping gastrointestinal disorders

Several studies have indicated an overlap between gastroesophageal reflux disease (GERD) and various functional gastrointestinal disorders (FGIDs). The overlapping conditions reported have mainly been functional dyspepsia (FD) and irritable bowel syndrome (IBS). The available literature is frequently based on symptomatic questionnaires or endoscopic procedures to diagnose GERD. Rarely, among patients with heartburn, pathophysiological evaluations have been considered to differentiate those with proven GERD from those without. Moreover, both GERD and IBS or FD showed enormous heterogeneity in terms of the criteria and diagnostic procedures used. The GERD-IBS overlap ranges from 3-79% in questionnaire-based studies and from 10-74% when GERD has been diagnosed endoscopically. The prevalence of functional dyspepsia (after normal upper endoscopy) is 12-15% and an overlap with GERD has been reported frequently. Only a few studies have considered a potential overlap between functional heartburn (FH) and IBS using a 24-h pH-metry or impedance-pH evaluation. Similar data has been reported for an overlap between FH and FD. Recently, a revision of the Rome criteria for esophageal FGIDs identified both FH and hypersensitive esophagus (HE) as potential functional esophageal disorders. This might increase the potential overlap between different FGIDs, with FH and HE rather than with GERD. The aim of the present review article was to appraise and discuss the current evidence supporting the possible concomitance of GERD with IBS and FD in the same patients and to evaluate how various GERD treatments could impact on the quality of life of these patients.

Roles of noradrenergic transmission within the ventral part of the bed nucleus of the stria terminalis in bidirectional brain-intestine interactions

Aims

The bed nucleus of the stria terminalis (BNST) is a limbic structure mediating autonomic and neuroendocrine responses and negative affective states such as anxiety and fear. We previously demonstrated that noradrenergic transmission via β‐adrenoceptors within the ventral part of BNST (vBNST) is involved in bidirectional interactions between the brain and the upper gastrointestinal (GI) tract. The present study aimed to examine the roles of intra‐vBNST noradrenergic transmission via β‐adrenoceptors in bidirectional interactions between the brain and lower GI tract.

Methods

In vivo microdialysis experiments were performed to examine colorectal distention (CRD)‐induced noradrenaline release within the vBNST of freely moving male Sprague‐Dawley rats. Colonic transit and abdominal pain perception were examined following intra‐vBNST injections of isoproterenol, a β‐adrenoceptor agonist, with and without co‐administration of timolol, a β‐adrenoceptor antagonist.

Results

CRD increased extracellular noradrenaline levels within the vBNST and evoked abdominal contractions in a pressure‐dependent manner (30‐60 mm Hg). Bilateral intra‐vBNST injections of isoproterenol (30 nmol/side) significantly increased CRD (30 mm Hg)‐induced abdominal contractions. Intra‐vBNST injections of isoproterenol (30 nmol/side) significantly increased colonic transit, which was reversed by co‐administration of timolol (30 nmol/side).

Conclusion

The results of this study suggest (a) the existence of a positive feedback loop between intra‐vBNST noradrenaline release and abdominal pain perception, and (b) the modulation of colonic motility by intra‐vBNST noradrenergic transmission via β‐adrenoceptors. Dysfunction of the lower GI tract may increase noradrenaline release within the vBNST, which, in turn, may exacerbate impairment of its motility and pain perception.

In vivo microdialysis experiments demonstrated that colorectal distention (CRD) increased extracellular levels of noradrenaline within the vBNST. Intra‐vBNST injections of isoproterenol, a β‐adrenoceptor agonist, induced visceral hypersensitivity to CRD and increased colonic transit, and the increase in colonic transit was reversed by co‐administration of timolol, a β‐adrenoceptor antagonist. The present findings demonstrated important roles of noradrenergic transmission via β‐adrenoceptors within the vBNST in bidirectional brain‐intestine interactions.

Plausibility criteria for putative pathophysiological mechanisms in functional gastrointestinal disorders: a consensus of experts

BACKGROUND AND AIMS

The functional gastrointestinal disorders (FGIDs) are extremely common conditions associated with a considerable personal, social and health economic burden. Managing FGIDs in clinical practice is challenging because of the uncertainty of symptom-based diagnosis, the high frequency of overlap between these conditions and the limited efficacy of available therapies. It has often been argued that successful drug development and management of FGIDs requires knowledge of the underlying pathophysiology. Numerous and highly variable candidate pathophysiological mechanisms have been implicated in the generation of FGID symptoms, but there is no current consensus on how to best define the relevance of these disturbances.

METHODS

A group of international experts on FGIDs developed plausibility criteria that should be fulfilled by relevant pathophysiological mechanisms in FGIDs.

RESULTS

Five criteria are proposed: (1) the presence of the abnormality in a subset of patients, (2) temporal association between proposed mechanism and symptom(s), (3) correlation between the level of impairment of the mechanism and symptom(s), (4) induction of the symptom(s) by provoking the pathophysiological abnormality in healthy subjects and (5) treatment response by a therapy specifically correcting the underlying disorder or congruent natural history of symptoms and dysfunction in the absence of specific therapy. Based on strength of evidence for these five criteria according to the Grading of Recommendations Assessment, Development and Evaluation system, a plausibility score can be calculated for each mechanism.

CONCLUSION

Evaluation of the strength of evidence for candidate pathophysiological abnormalities fulfilling these five plausibility criteria will help to identify the most relevant mechanisms to target for novel diagnostic approaches and for the development of new therapies.

Aberrant default mode network in patients with primary dysmenorrhea: a fMRI study

Primary dysmenorrhea (PDM), characterized by cramping pain in the lower abdomen, is a common gynecological disorder in women of child-bearing age. An increasing number of neuroimaging studies have emphasized that PDM is associated with functional and structural abnormalities in the regions related to the default mode network (DMN). Based on resting-state functional magnetic resonance imaging (fMRI), the aim of this study was to use amplitude of low-frequency fluctuation (ALFF) and functional connectivity (FC) to investigate changes of the intrinsic brain activity in the DMN in PDM. Pearson correlation analysis was conducted to assess relationships between the neuroimaging findings and clinical symptoms. Forty-eight PDM patients and thirty-eight matched healthy controls participated in this study. Compared to healthy controls, PDM patients had increased ALFF in the precuneus, dorsomedial prefrontal cortex (dmPFC) and anterior cingulate cortex (ACC) and decreased ALFF in the thalamus. PDM patients also had decreased connectivity between the precuneus and left dmPFC and right ACC, while increased connectivity between the precuneus and left thalamus. In addition, the ALFF in the left dmPFC in PDM patients positively correlated with disease duration. Our findings provide further evidence of the DMN-related abnormalities in PDM patients which might contribute to a better understanding of the pathophysiology of this disease.

Self-reported Sleep Impairment in Functional Dyspepsia and Irritable Bowel Syndrome

BACKGROUND/AIMS

Sleep impairment is a common complaint among patients with irritable bowel syndrome (IBS) and functional dyspepsia (FD). This study aimed to evaluate the prevalence of sleep impairment in FD or IBS patients, and to determine whether IBS-FD overlap induced more sleep disturbance than FD or IBS alone.

METHODS

A population-based cohort in South Korea including 2251 subjects was asked about gastrointestinal symptoms including IBS and dyspepsia-related symptoms. In addition, sleep disturbance was measured using the Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale questionnaires. One-way ANOVA and logistic regression were used to assess differences among the 4 groups (healthy subjects, IBS alone, FD alone, and IBS-FD overlap).

RESULTS

Of 2251 subjects who were surveyed by questionnaire, 2031 responded (92.5% response rate) and were analyzed. The prevalence of IBS, FD, and IBS-FD overlap was 8.0% (95% confidence interval [CI], 6.8-9.2%), 4.8% (95% CI, 3.9-5.8%), and 1.8% (95% CI, 1.2-2.4%), respectively. FD alone, but not IBS alone, was significantly associated with a poorer sleep quality index (OR, 2.68; 95% CI, 1.43-5.01) and more daytime sleepiness (OR, 2.21; 95% CI, 1.14-4.30), compared to healthy subjects. IBS-FD overlap had the greatest likelihood of a poorer sleep quality index (OR, 3.88; 95% CI, 1.83-8.19), daytime sleepiness (OR, 2.47; 95% CI, 1.01-5.67), and insomnia (OR, 2.84; 95% CI, 1.39-5.82), compared to healthy subjects.

CONCLUSION

A correlation between functional gastrointestinal disorders and sleep disturbance was demonstrated, which was significantly pronounced in the context of IBS-FD overlap.

Regional Brain Activity During Rest and Gastric Water Load in Subtypes of Functional Dyspepsia: A Preliminary Brain Functional Magnetic Resonance Imaging Study

Background/Aims

Functional dyspepsia (FD) remains a great clinical challenge since the FD subtypes, defined by Rome III classification, still have heterogeneous pathogenesis. Previous studies have shown notable differences in visceral sensation processing in the CNS in FD compared to healthy subjects (HS). However, the role of CNS in the pathogenesis of each FD subtype has not been recognized.

Methods

Twenty-eight FD patients, including 10 epigastric pain syndrome (EPS), 9 postprandial distress syndrome (PDS), and 9 mixed-type, and 10 HS, were enrolled. All subjects underwent a proximal gastric perfusion water load test and the regional brain activities during resting state and water load test were investigated by functional magnetic resonance imaging.

Results

For regional brain activities during the resting state and water load test, each FD subtype was significantly different from HS (P < 0.05). Focusing on EPS and PDS, the regional brain activities of EPS were stronger than PDS in the left paracentral lobule, right inferior frontal gyrus pars opercularis, postcentral gyrus, precuneus, insula, parahippocampal gyrus, caudate nucleus, and bilateral cingulate cortices at the resting state (P < 0.05), and stronger than PDS in the left inferior temporal and fusiform gyri during the water load test (P < 0.05).

Conclusions

Compared to HS, FD subtypes had different regional brain activities at rest and during water load test, whereby the differences displayed distinct manifestations for each subtype. Compared to PDS, EPS presented more significant differences from HS at rest, suggesting that the abnormality of central visceral pain processing could be one of the main pathogenesis mechanisms for EPS.

Self-reported Sleep Impairment in Functional Dyspepsia and Irritable Bowel Syndrome

Background/Aims

Sleep impairment is a common complaint among patients with irritable bowel syndrome (IBS) and functional dyspepsia (FD). This study aimed to evaluate the prevalence of sleep impairment in FD or IBS patients, and to determine whether IBS-FD overlap induced more sleep disturbance than FD or IBS alone.

Methods

A population-based cohort in South Korea including 2251 subjects was asked about gastrointestinal symptoms including IBS and dyspepsia-related symptoms. In addition, sleep disturbance was measured using the Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale questionnaires. One-way ANOVA and logistic regression were used to assess differences among the 4 groups (healthy subjects, IBS alone, FD alone, and IBS-FD overlap).

Results

Of 2251 subjects who were surveyed by questionnaire, 2031 responded (92.5% response rate) and were analyzed. The prevalence of IBS, FD, and IBS-FD overlap was 8.0% (95% confidence interval [CI], 6.8–9.2%), 4.8% (95% CI, 3.9–5.8%), and 1.8% (95% CI, 1.2–2.4%), respectively. FD alone, but not IBS alone, was significantly associated with a poorer sleep quality index (OR, 2.68; 95% CI, 1.43–5.01) and more daytime sleepiness (OR, 2.21; 95% CI, 1.14–4.30), compared to healthy subjects. IBS-FD overlap had the greatest likelihood of a poorer sleep quality index (OR, 3.88; 95% CI, 1.83–8.19), daytime sleepiness (OR, 2.47; 95% CI, 1.01–5.67), and insomnia (OR, 2.84; 95% CI, 1.39–5.82), compared to healthy subjects.

Conclusion

A correlation between functional gastrointestinal disorders and sleep disturbance was demonstrated, which was significantly pronounced in the context of IBS-FD overlap.

Effect of intragastric FODMAP infusion on upper gastrointestinal motility, gastrointestinal, and psychological symptoms in irritable bowel syndrome vs healthy controls

BACKGROUND

The low fermentable oligo-, di-, mono-saccharides and polyol (FODMAP) diet is a treatment strategy to reduce symptoms of irritable bowel syndrome (IBS). Acute effects of FODMAPs on upper gastrointestinal motility are incompletely understood. Our objectives were to assess the acute effects of intragastric FODMAP infusions on upper gastrointestinal motility and gastrointestinal and psychological symptoms in healthy controls (HC) and IBS patients.

METHODS

A high-resolution solid-state manometry probe and an infusion tube were positioned into the stomach. Fructans, fructose, FODMAP mix, or glucose was intragastrically administered to HC, and fructans or glucose was administered to IBS patients until full satiation (score 0-5), in a randomized crossover fashion. Manometric measurements continued for 3 hours. Gastrointestinal and psychological symptoms were assessed by questionnaires at predefined time points. The study was registered on www.clinicaltrials.gov (NCT02980406).

KEY RESULTS

Twenty HC and 20 IBS patients were included. Fructans induced higher postprandial gastric pressures compared with glucose over both groups (P<.001). Bloating, belching, and pain increased more in IBS over both carbohydrates (P<.041). In addition, IBS patients reported more flatulence and cramps compared with HC following fructans (P<.001). Glucose induced more fatigue and dominance compared with fructans (P=.028, P=.001). Irritable bowel syndrome patients reported a higher increase in anger (P=.030) and a stronger decrease in positive affect (P=.021).

CONCLUSIONS & INFERENCES

The upper gastrointestinal motility response varies between carbohydrates. Irritable bowel syndrome patients are more sensitive to fructan infusion, reflected in their higher gastrointestinal symptom scores. Acute carbohydrate infusion can have differential psychological effects in IBS and HC.

Pathophysiology of Gastroesophageal Reflux Disease

The pathogenesis of gastroesophageal reflux disease (GERD) is complex and involves changes in reflux exposure, epithelial resistance, and visceral sensitivity. The gastric refluxate is a noxious material that injures the esophagus and elicits symptoms. Esophageal exposure to gastric refluxate is the primary determinant of disease severity. This exposure arises via compromise of the anti-reflux barrier and reduced ability of the esophagus to clear and buffer the refluxate, leading to reflux disease. However, complications and symptoms also occur in the context of normal reflux burden, when there is either poor epithelial resistance or increased visceral sensitivity. Reflux therefore develops via alterations in the balance of aggressive and defensive forces.

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.

Sensory Over-Responsiveness among Healthy Subjects is Associated with a Pronociceptive State

OBJECTIVE

Chronic pain patients show hypersensitivity to sensory nonpainful stimuli. Sensory over-responsiveness (SOR) to innocuous daily stimuli, experienced as painful, is prevalent in 10% of the healthy population. This altered sensory processing may be an expression of overfacilitation, or a less efficient pain-inhibitory process in the pain pathways. We therefore aimed to investigate specifically the pain-inhibitory system of subjects with SOR who are otherwise healthy, not studied as of yet.

METHODS

Thirty healthy subjects, divided into an SOR group (n = 14) and a non-SOR group (n = 16) based on responses to the Sensory Responsiveness Questionnaire, were psychophysically tested in order to evaluate (1) hyperalgesic responses; (2) adaptation/sensitization to 14 phasic heat stimuli; (3) habituation; (4) 6-minute after-sensations; and (5) conditioned pain modulation (CPM) (ie, phasic heat stimuli applied with and without hand immersion in a hot water bath).

RESULTS

The SOR group differed from the non-SOR group in (1) a steeper escalation in NPS ratings to temperature increase (P = 0.003), indicating hyperalgesia; (2) increased sensitization (P < 0.001); (3) habituation responses (P < 0.001); (4) enhanced pain ratings during the after-sensation (P = 0.006); and (5) no group difference was found in CPM.

CONCLUSIONS

SOR is associated with a pronociceptive state, expressed by amplification of experimental pain, yet with sufficient inhibitory processes. Our results support previous findings of enhanced facilitation of pain-transmitting pathways but also reveal preserved inhibitory mechanisms, although they were slower to react.

Stress and sleep quality in doctors working on-call shifts are associated with functional gastrointestinal disorders

AIM

To investigate the role of sleep quality and psychosocial problems as predictors of functional gastrointestinal disorders (FGIDs) in doctors that work 24 hour-on-call shifts.

METHODS

In this cross-sectional observation study, using the Rome III Questionnaire and Pittsburgh Sleep Quality Index (PSQI), we analyzed 170 doctors with 24 hour-on-call shifts.

RESULTS

Among the participants that had experienced a 24 hour-on-call shift within the last 6 mo, 48 (28.2%) had FGIDs. Overall prevalence of irritable bowel syndrome (IBS) and functional dyspepsia (FD) were 16.5% and 17.1%, respectively, with 5.3% exhibiting both. Sleep scores (PSQI) (8.79 ± 2.71 vs 7.30 ± 3.43, P = 0.008), the presence of serious psychosocial alarm (83.3% vs 56.6%, P = 0.004), and the proportion of doctors who experienced over two months of recent on-call work (81.2% vs 68.9%, P = 0.044) were significantly different between individuals with or without FGIDs. Multivariate analysis revealed that presenting serious psychosocial alarm was an independent risk factor for prevalence of FD (OR = 5.47, 95%CI: 1.06-28.15, P = 0.042) and poor sleep quality (PSQI ≥ 6) was a predictor of IBS (OR = 4.17, 95%CI: 1.92-19.02, P = 0.016).

CONCLUSION

Physicians should recognize the role of sleep impairment and psychological stress in the development of FGIDs and a comprehensive approach should be considered to manage patients with FGIDs.