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

The impact of depression-mediated gut microbiota composition on Irritable Bowel Syndrome: A Mendelian study

OBJECTIVE

This study uses a two-sample Mendelian randomization (MR) analysis to delineate the causal influence of gut microbiota on the occurrence of irritable bowel syndrome (IBS), concurrently assessing the potential mediating function of depression within this framework.

METHODS

Several two-sample MR methods were used to assess the causal repercussions of gut microbiota on the onset of both IBS and depression. Following this, gut microbiota and depression, which demonstrated notable causal associations, were integrated as exposure variables in a multivariable Mendelian randomization (MVMR) framework to construct a model encompassing gut microbiota, depression, and IBS. Mediation effects were assessed by examining the indirect pathway of gut microbiota → depression → IBS.

RESULTS

Two-sample MR analysis unveiled a statistically significant causal association (P < 0.05) between specific bacterial group within the gut microbiota, notably p_Actinobacteria(OR = 0.829225), c_Clostridia(OR = 0.798897), s_Desulfovibrio_piger(OR = 1.163912), g_Streptococcus(OR = 1.132735), c_Actinobacteria(OR = 0.829224), and the onset of IBS. In the MVMR analysis, the relationship between depression and IBS was significant across Model 3, Model 7, Model 8, and Model 13 (P < 0.05). Assessment of mediation effects revealed that c_Clostridia and o_Clostridiales indirectly impacted IBS through depression, with masking effect ratios of 168.46 % and 168.44 %, respectively.

CONCLUSION

These findings underscore a resilient causal association between the composition of gut microbiota and the initiation of IBS. Furthermore, depression serves as a mediator for particular groups of gut bacteria, thereby contributing to the development of IBS. These observations imply that interventions targeting mental health may potentially alleviate the risk of IBS onset attributable to adverse configurations of gut microbiota.

Prevalence of extra-intestinal symptoms according to irritable bowel syndrome subtype

BACKGROUND

Irritable bowel syndrome (IBS) is a functional disorder commonly associated with extra-intestinal symptoms. However, the prevalence of these symptoms according to IBS subtype is not well established.

AIM

To compare the prevalence of extra-intestinal symptoms among patients with different subtypes of IBS.

METHODS

A descriptive cross-sectional study including patients with IBS according to Rome IV criteria was performed between July 2022 and April 2023. Patients were classified according their subtype of IBS: IBS-D (diarrhea-predominant), IBS-C (constipation-predominant), and IBS-M (mixed bowel habits). Patients completed the IBS severity scoring system questionnaire (IBS-SSS) to determine severity of IBS symptoms and patient health questionnaire- 9 (PHQ-9) to define presence and severity of depressive symptoms. The prevalence of reported extra-intestinal symptoms was also assessed and compared between groups.

KEY RESULTS

A total of 4862 patients with IBS were included; 608 IBS-D (12.5%), 1978 IBS-C (40.7%), and 2276 IBS-M (46.8%). Patients with IBS-C had significantly lower IBS-symptoms severity (mean IBS-SSS 290 vs. 310 and 320 for IBS-D and IBS-M, respectively, p = 0.03). The prevalence of obesity was also significantly lower in these patients (17.1% vs. 30.9% IBS-D and 27.9% IBS-M, p = 0.0001). Patients with IBS-D showed a significantly higher prevalence of food intolerance perception (9.5%, p = 0.03), history of cholecystectomy (17.8%, p = 0.03), and fecal incontinence (36.2%, p = 0.0001) as compared to the other groups. Patients with IBS-M had significantly higher mean PHQ-9 score (12.7 vs. 11.1 IBS-D and 10.5 IBS-C, p = 0.001) and prevalence of depressive symptoms (80.0%, p = 0.01). Patients with IBS-M also had higher prevalence of extra-intestinal symptoms such as arthralgia (62.4%, p = 0.0001), extremity numbness (64.5%, p = 0.0001), atopic dermatitis (28.2%, p = 0.02), and chronic cervicalgia (81.0%, p = 0.01).

CONCLUSIONS & INFERENCES

The prevalence of most extra-intestinal symptoms is higher among patients with IBS-M. Further research is needed to better characterize IBS subtypes, which could potentially help refining tailored therapeutic strategies.

Weak Relationships Between Psychological Factors and Experimental Pain Outcomes in Pain-Free Individuals: An Aggregate Analysis of 8 Studies

Although psychological factors such as anxiety, depression, and pain catastrophizing are known to influence pain outcomes in chronic pain populations, there are mixed results regarding whether they influence experimental pain outcomes in pain-free individuals. The objectives of this study were to determine the associations between psychological factors and experimental pain outcomes in pain-free adolescents and adults. Relationships between anxiety, depression, and pain catastrophizing and experimental pain outcomes across 8 different studies (total N = 595) were examined in different populations of pain-free adult and adolescent participants. Analyses were conducted with and without controlling for sex, age, and race. Studies were analyzed separately and as part of an aggregate analysis. Individual study analyses resulted in 136 regression models. Of these, only 8 models revealed a significant association between psychological factors and pain outcomes. The significant results were small and likely due to Type 1 error. Controlling for demographic factors had minimal effect on the results. The aggregate analyses revealed weak relationships between anxiety and pressure pain threshold (Fisher's z = -.10 [-.19, -.01]), anxiety and cold pain intensity ratings (Fisher's z = .18 [.04, .32]), and pain catastrophizing and pressure pain threshold (Fisher's z = -.14 [-.26, -.02]). Sample size calculations based on the aggregate analyses indicated that several hundred participants would be required to detect true relationships between these psychological factors and pain measures. The overall negative findings suggest that in pain-free individuals, anxiety, depression, and pain catastrophizing are not meaningfully related to experimental pain outcomes. PERSPECTIVE: Psychological variables have been shown to predict pain outcomes in chronic pain populations but these relationships may not generalize to pain-free populations. An analysis of 595 pain-free individuals across 8 studies in our lab revealed that anxiety, depression, and pain catastrophizing were not meaningfully related to experimental pain outcomes.

A randomized, double-blinded, placebo-controlled clinical trial on Lactobacillus-containing cultured milk drink as adjuvant therapy for depression in irritable bowel syndrome

Irritable bowel syndrome (IBS) is frequently linked with coexisting mental illnesses. Our previous study discovered that 32.1% of IBS patients had subthreshold depression (SD), placing them at higher risk of developing major depression. Gut microbiota modulation through psychobiotics was found to influence depression via the gut-brain axis. However, the efficacy of lessening depression among IBS patients remains ambiguous. The study's aim was to investigate the roles of cultured milk drinks containing 109 cfu Lactobacillus acidophilus LA-5 and Lactobacillus paracasei L. CASEI-01 on depression and related variables among IBS participants with SD. A total of 110 IBS participants with normal mood (NM) and SD, were randomly assigned to one of four intervention groups: IBS-NM with placebo, IBS-NM with probiotic, IBS-SD with placebo, and IBS-SD with probiotic. Each participant was required to consume two bottles of cultured milk every day for a duration of 12 weeks. The following outcomes were assessed: depression risk, quality of life, the severity of IBS, and hormonal changes. The depression scores were significantly reduced in IBS-SD with probiotic and placebo from baseline (p < 0.001). Only IBS-SD with probiotic showed a significant rise in serotonin serum levels (p < 0.05). A significantly higher life quality measures were seen in IBS-SD with probiotic, IBS-SD with placebo, and IBS-NM with placebo (p < 0.05). All groups, both placebo and probiotic, reported significant improvement in IBS severity post-intervention with a higher prevalence of remission and mild IBS (p < 0.05). Dual strains lactobacillus-containing cultured milk drink via its regulation of relevant biomarkers, is a potential anti-depressive prophylactic agent for IBS patients at risk.

Intensive short-term dynamic psychotherapy for irritable bowel syndrome: a randomized controlled trial examining improvements in emotion regulation, defense mechanisms, quality of life, and IBS symptoms

Studies have provided evidence for the effectiveness of intensive short-term dynamic psychotherapy (ISTDP) in treating medically unexplained symptoms (MUS). This study aimed to examine the effectiveness of ISTDP on individuals living with irritable bowel syndrome (IBS) in terms of, emotion regulation (ER) abilities, defense mechanisms, quality of life (QOL), and IBS symptoms. A total of 30 patients diagnosed with IBS were recruited and randomly assigned to either the intervention (n = 15) or control (n = 15) group. Pre- and post-treatment assessments were conducted, along with a follow-up assessment after ten weeks. Repeated measures analyses of variance were employed to analyze the data. The findings revealed that ISTDP led to significant improvements in ER, defense mechanisms, and QOL, as well as a reduction in the severity and frequency of IBS symptoms. These results provide further support for the efficacy of ISTDP as a treatment modality for individuals with IBS.

The role of the gastrointestinal barrier in obesity-associated systemic inflammation

Systemic inflammation is a key contributor to the onset and progression of several obesity-associated diseases and is thought to predominantly arise from the hyperplasia and hypertrophy of white adipose tissue. However, a growing body of works suggests that early changes in the gastrointestinal (GI) barrier may contribute to both local, within the GI lining, and systemic inflammation in obesity. Intestinal barrier dysfunction is well-characterized in inflammatory GI disorders such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) and is known to contribute to systemic inflammation. Thus, drawing parallels between GI disorders, where intestinal permeability and systemic inflammation are prominent features, and obesity-induced GI manifestations may provide insights into the potential role of the intestinal barrier in systemic inflammation in obesity. This review summarizes the current literature surrounding intestinal barrier dysfunction in obesity and explores the potential role of intestinal hyperpermeability and intestinal barrier dysfunction in the development of systemic inflammation and GI dysfunction in obesity.

Major depressive disorder and the risk of irritable bowel syndrome: A Mendelian randomization study

BACKGROUND

The association between major depressive disorder (MDD) and irritable bowel syndrome (IBS) has been found in observational research; however, the causative relationship between MDD and IBS remains uncertain. Using the two-sample Mendelian randomization (MR) approach, we attempted to examine the causal effect of MDD on IBS.

METHODS

Independent genetic variants for MDD identified by Howard et al. based on a genome-wide meta-analysis were selected for this study. Gene-Outcome associations for IBS were gathered from UK Biobank and FinnGen databases. The MR analysis included inverse variance weighted (IVW), MR-Egger regression, weighted median, weighted mode, and MR-PRESSO sensitivity analyses.

RESULTS

FinnGen database subjected to inverse variance weighted (IVW) analysis revealed that MDD may be a risk factor for the development of IBS (OR = 1.356, 95% CI: 1.125-1.632, p = 0.0013). The same finding was reached in UK Biobank for IVW (OR = 1.011, 95% CI: 1.006-1.015, p = 3.18 × 10-7 ), MR-Egger progression (OR = 1.030, 95% CI: 1.008-1.051, p = 0.007), and weighted median (OR = 1.011, 95% CI: 1.005-1.016, p = 0.0001).

CONCLUSION

Our findings supported a causal relationship between MDD and IBS, which may have implications for the clinical management of IBS in individuals with MDD.

Somatization Mediates the Relationship Between Childhood Trauma and Pain Ratings in Patients with Irritable Bowel Syndrome

GOALS

To identify potential mechanisms by which childhood trauma may lead to the adult development of abdominal symptoms in patients with irritable bowel syndrome (IBS).

BACKGROUND

Patients with IBS frequently report a history of childhood trauma. The pathophysiology by which abdominal pain arises in patients with IBS is multidimensional, consisting of both peripheral factors, such as altered motility, inflammation, and bacterial overgrowth, as well as central factors, such as psychological distress and neuro-hormonal dysregulation.

STUDY

Adult psychological factors (anxiety, depression, and somatization) were examined to determine if they mediate the relationship between retrospective reports of childhood trauma and current adult IBS abdominal symptoms in a study of 436 patients (M age=41.6, 79% F) meeting Rome III diagnosis criteria. Childhood trauma was measured using retrospective questions assessing physical and sexual abuse. Psychological factors in adulthood were measured with the subscales of the Brief Symptom Inventory-18. Outcome variables included adult IBS symptoms of abdominal pain, bloating, and satisfaction with bowel habits from the IBS Symptoms Severity Scale.

RESULTS

Results indicated that somatization mediated the relationship between childhood abuse and abdominal pain and bloating but not bowel satisfaction.

CONCLUSIONS

This study provides insight into the multifactorial nature of IBS-associated abdominal pain in patients with a history of childhood trauma, elucidating the need for a trauma-informed treatment approach for patients with histories of abuse.

Evaluation of the causal effects of blood metabolites on irritable bowel syndrome: Mendelian randomization

BACKGROUND

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder characterized by abdominal pain, discomfort, and changes in bowel habits. The mechanism underlying IBS remains unclear, and little evidence exists for clarifying the causal relationship between blood metabolites and IBS.

METHODS

We conducted a Mendelian randomization (MR) study using two samples. Exposure data for 7824 Europeans were extracted from a genome-wide association study (GWAS) on metabolite levels. The IBS GWAS data from the GWAS database were used for the initial analysis. The primary analysis of causal relationships was conducted using inverse-variance weighting (IVW) with MR-Egger and weighted medians as supplementary analyses. Sensitivity analyses were performed using a combination of the Cochran's Q test, MR-Egger intercept test, Mendelian randomization pleiotropy residual sum and outlier, and leave-one-out analysis. For significant associations, replication and meta-analyses were performed using additional independent IBS case GWAS data released by the FinnGen Consortium R9. To identify the metabolites, score regression, confounding analysis, and reverse MR were performed to further assess the causal relationships between the metabolites.

RESULTS

After rigorous screening, we identified four known metabolites to be associated with IBS (stearate, odds ratio [OR]: 0.74, 95% confidence interval [CI]: 0.59-0.92; arginine, OR: 1.36, 95% CI: 1.07-1.74; 1-palmitoylglycerol, OR:1.49, 95% CI: 1.07-2.07; 1-palmitoylglycerophosphoinositol, OR: 0.84, 95% CI: 0.71-0.99).

CONCLUSIONS

MR analysis revealed a causal relationship between the four metabolites and IBS, providing preliminary evidence for the pathogenesis of IBS. Our results provide novel insights into the potential biomarkers of IBS.

Sera anti-neuronal antibodies in patients with irritable bowel syndrome and their correlations with clinical profiles

BACKGROUND

Immune factors were involved in the pathophysiology of irritable bowel syndrome (IBS). The aim of the study was to test anti-neuronal antibodies in sera of IBS patients and demonstrate their correlations with IBS profiles and psychological disorders.

METHODS

Patients with IBS met Rome III criteria and excluded organic diseases were enrolled. Controls included healthy subjects (HS), slow transit functional constipation, autoimmune diseases, and so on. Indirect immunofluorescence with monkey cerebellum and small intestine as substrates was used to detect anti-neuronal antibodies including anti-cerebral neuronal antibodies (ACNA) and anti-enteric neuronal antibodies (AENA).

RESULTS

A total of 293 IBS patients, 100 HS and 153 disease controls were included in this study. The ACNA positive rate of IBS patients was significantly higher than HS (14% vs. 6%, p = 0.033). The positive rate of ACNA was significantly lower than AENA (14.0% vs. 76.8%, p = 0.028) in IBS patients. The prevalence of headache and sleeping disorder were higher in ACNA-positive IBS patients than ACNA-negative IBS patients (61% vs. 42.9%, p = 0.03; 75.6% vs. 57.1%, p = 0.03, respectively). Among IBS patients, ACNA and AENA were both negative in 21.8% patients, ACNA negative and AENA positive in 64.2% patients, and ACNA and AENA were both positive in 12.6% patients. There were no significant differences of intestinal symptoms among the three groups, while the prevalence of headache (64.9% vs. 37.5% and 44.7%, p = 0.03) and sleeping disorder (78.4% vs. 50.0% and 59.6%, p = 0.02) were higher in patients with both ACNA and AENA positive than patients with both ACNA and AENA negative, patients with ACNA negative and AENA positive. There were no significant differences of the prevalence of depression and anxiety, HAMD, and HAMA scores among the three groups.

CONCLUSIONS AND INFERENCES

Anti-neuronal antibodies in sera of IBS patients were mainly targeted to enteric neurons and in a small part to cerebral neurons. ACNA were closely related to headache and sleeping disorder but unrelated to intestinal symptoms, depression, or anxiety of IBS patients.

Risk Factor Analysis and Intervention Study for Unspecific Functional Enteropathy in a Maritime Environment: A Cross-Sectional Analytical Survey

Background

The study aimed to investigate the risk factors and interventions for unspecific functional bowel disorders (U-FBDs) in military personnel under maritime environment.

Methods

This cross-sectional analytical survey used the Rome III questionnaire for surveying 1018 military personnel involved in overseas humanitarian medical services from June 2013 to January 2016. Individuals diagnosed with U-FBDs were included in the U-FBDs group, while those without FBDs or other diseases were considered the control group. The psychological and sleep conditions of military personnel with U-FBDs were assessed using the SCL-90 scale and the Pittsburgh Sleep Quality Index scale, respectively. Health education and treatment were provided to individuals diagnosed with U-FBDs, and the improvements were evaluated after three months.

Results

Among 923 qualified questionnaires, 243 subjects was included in U-FBDs group and 240 in the control group. Smoking, alcohol consumption, and multiple seafaring missions were identified as risk factors for U-FBDs in military personnel on ocean-going missions. The U-FBDs group had significantly worse sleep quality, sleep efficiency, daytime dysfunction score, and total PSQI score compared to the control group (P < 0.05). Additionally, 10 factor scores of SCL-90 and the total score in the U-FBDs group were significantly higher than those in the control group (P < 0.01). Patients with U-FBDs also reported the highest rate of somatic symptoms (P < 0.01).

Conclusion

The onset of U-FBDs among military personnel on long-haul maritime may be closely related to mental, psychological, and sleep factors. Health education and treatment may help improve the symptoms of U-FBDs.

Diagnosis of Irritable Bowel Syndrome: Primary Care Physicians Compared with Gastroenterologists

Objective: To examine disparities between primary care provider (PCP) and gastroenterologist diagnosis and management of irritable bowel syndrome (IBS).Design: Retrospective cross-sectional study.Setting: A 547-bed quaternary-care hospital within the Loyola University Healthcare System.Participants: 1000 patients aged 18-65 with an ICD-10 diagnosis of IBSMethods: We randomly selected 1000 patients aged 18 to 65 years within the Loyola University Healthcare System's electronic medical record with an ICD-10 diagnosis of IBS. Physician notes and diagnostic results were reviewed for documentation of symptoms fulfilling Rome IV criteria and resolution of symptoms. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of primary diagnoses assigned by PCPs and gastroenterologists were assessed along with number of diagnostic tests ordered.Results: The mean age (SD) was 45 (12) years, and 76.9% were female. Sensitivity of an IBS diagnosis by a PCP was 77.6% (95% CI 73.3-81.9), compared with 60.1% (95% CI 54.7-65.6) for a gastroenterologist. Specificity of an IBS diagnosis by a PCP was 27.5% (95% CI 23.5-31.5), compared with 71.1% (95% CI 64.6-77.5) for a gastroenterologist diagnosis of IBS. A gastroenterologist diagnosis of IBS carried a high PPV (77.3%, 95% CI 72.0-82.6) compared with 44.6% (95% CI 40.7-48.5) for a PCP. Of 180 patients with outcome data, 69.4% had resolution of symptoms at follow-up.Conclusion: The sensitivity of gastroenterologist diagnosis of IBS closely matches the sensitivity of Rome IV criteria in validation studies. The high specificity and PPV of gastroenterologists suggest more cautious diagnosis by gastroenterologists, with PCPs more likely to assign a diagnosis of IBS incorrectly or without sufficient documentation of symptoms fulfilling Rome IV criteria. Reported resolution rates suggest primary care management of IBS is appropriate, but PCPs may benefit from gastroenterologist consultation and diagnostic guidelines for greater specificity in diagnosing IBS.

The relationship between anxiety and irritable bowel syndrome symptoms among females: A cross-sectional study in Egypt

There is a scarcity of studies focusing on irritable bowel syndrome (IBS) and anxiety in Egypt. Accordingly, our study aimed to assess the association between anxiety and IBS symptomatology among Egyptian females. Three hundred eighty-three females (145 IBS and 238 controls) were included in the study, and data were obtained using structured predesigned questionnaires. IBS and anxiety symptoms were assessed according to the Rome IV criteria and the Arabic version of the beck anxiety inventory, respectively. Both IBS and non-IBS groups showed increased anxiety during the pandemic, without a significant difference between both groups (P value = .657). Higher levels of education were significantly associated with severe anxiety (P value = .031). Multivariate analysis of IBS patients showed that intermediate education was significantly associated with 75% lower odds for increased IBS symptoms compared with illiterate or read-and-write IBS patients [odds ratio (OR): 0.25, 95% confidence interval (CI) 0.06-0.95, P value = .042]. Urban residence was significantly associated with 13.5 times greater odds of increased IBS symptoms, compared with rural residence (OR: 13.48, 95% CI 3.55-51.25, P value < .001). Moreover, patients who lost their job during the pandemic were 12.9 times more likely to have increased symptoms (OR: 12.89, 95% CI 1.84-90.15, P value = 0.01). A unit increase in patients age and beck anxiety inventory score was associated with 68% and 75% greater odds for increased IBS symptoms, respectively (OR: 1.68, 95% CI 1.12-2.53, P value = .012; OR: 1.75, 95% CI 1.08-2.84, P value = .024). Increasing anxiety is associated with increased IBS symptoms. Therefore, IBS patients should be screened for anxiety, and the role of psychiatric management of anxiety in the amelioration of IBS symptoms must be explored.

Association of mental health conditions and functional gastrointestinal disorders among Vietnamese new-entry medical students

BACKGROUND

Functional gastrointestinal disorders (FGIDs), also known as disorders of gut-brain interaction, occur not only in the elderly but also in young adults. This study aimed to evaluate the association between mental health conditions and FGIDs among Vietnamese new-entry medical students.

METHODS

This cross-sectional study was conducted in February 2022 among new-entry medical students in Ho Chi Minh City, Vietnam. A printed questionnaire was distributed to all students on the day of freshmen health screening. Their urine samples were collected to screen for Helicobacter pylori infection using rapid urinary test. FGIDs were diagnosed using ROME IV criteria. Gastroesophageal reflux disease (GERD) was defined as the presence of typical reflux symptoms at least twice a week. Mental health conditions, including generalized anxiety disorder (GAD) and major depressive disorder (MDD), were identified using Generalized Anxiety Disorder Assessment-7 (GAD-7) and Patient Health Questionnaire-9 (PHQ-9) scales, respectively.

RESULTS

Among 400 new-entry medical students who participated in the study, the overall prevalence of FGIDs was 10.3% (functional dyspepsia 6.5%, irritable bowel disease 5.5%). The overlap syndrome (OS) of GERD-FGIDs or different FGIDs was present in 3.0% of participants. The prevalences of GAD and MDD were 6.8% and 10.2%, respectively. The urinary test was positive in 180 (45.0%) participants. In the multivariable logistic regression analysis, MDD was significantly associated with not only the risk of FGIDs (OR = 5.599, 95%CI: 2.173-14.430, p<0.001) but also the risk of OS (OR = 10.076, 95CI%: 2.243-45.266, p = 0.003).

CONCLUSIONS

MDD is associated with FGIDs and OS among new-entry medical students.

Assessing the relationship between gut microbiota and irritable bowel syndrome: a two-sample Mendelian randomization analysis

BACKGROUND

Growing evidence has suggested that gut microbiota is closely related to the risk of irritable bowel syndrome (IBS), but whether there is a causal effect remains unknown. We adopted a Mendelian randomization (MR) approach to evaluate the potential causal relationships between gut microbiota and the risk of IBS.

METHODS

Genetic instrumental variables for gut microbiota were identified from a genome-wide association study (GWAS) of 18,340 participants. Summary statistics of IBS were drawn from a GWAS including 53,400 cases and 433,201 controls. We used the inverse-variance weighted (IVW) method as the primary analysis. To test the robustness of our results, we further performed the weighted-median method, MR-Egger regression, and MR pleiotropy residual sum and outlier test. Finally, reverse MR analysis was performed to evaluate the possibility of reverse causation.

RESULTS

We identified suggestive associations between three bacterial traits and the risk of IBS (odds ratio (OR): 1.08; 95% confidence interval (CI): 1.02, 1.15; p = 0.011 for phylum Actinobacteria; OR: 0.95; 95% CI: 0.91, 1.00; p = 0.030 for genus Eisenbergiella and OR: 1.10; 95% CI: 1.03, 1.18; p = 0.005 for genus Flavonifractor). The results of sensitivity analyses for these bacterial traits were consistent. We did not find statistically significant associations between IBS and these three bacterial traits in the reverse MR analysis.

CONCLUSIONS

Our systematic analyses provide evidence to support a potential causal relationship between several gut microbiota taxa and the risk of IBS. More studies are required to show how the gut microbiota affects the development of IBS.

Upper gastrointestinal endoscopic findings in functional constipation and irritable bowel syndrome diagnosed using the Rome IV criteria: a cross-sectional survey during a medical check-up in Japan

BACKGROUND

The Rome IV criteria have been established as an international standard for diagnosing disorders of gut-brain interaction. In this study, we aimed to examine the upper gastrointestinal (GI) endoscopic findings and symptoms of subjects with functional constipation (FC) and irritable bowel syndrome (IBS) of individuals undergoing a medical check-up.

METHODS

A total of 13,729 subjects underwent a medical check-up at Osaka City University-affiliated clinic, MedCity21, between April 2018 and March 2019. Among the 5,840 subjects who underwent screening upper GI endoscopy and completed a questionnaire based on the Rome IV criteria, 5,402 subjects were consecutively enrolled after excluding subjects with a large amount of gastric residue (n = 6), those who had previously undergone partial or total gastrectomy (n = 40), or those with daily use of low-dose aspirin (n = 82), nonsteroidal anti-inflammatory drugs (n = 63), or acid secretion inhibitors (n = 308).

RESULTS

Robust Poisson regression analyses adjusted for age, sex, Helicobacter pylori infection status, alcohol intake, and smoking habits showed a significant association between FC and corpus erosion (adjusted prevalence ratio [aPR], 2.93; 95% confidence interval [CI], 1.51-5.67; p < 0.01) and red streaks (aPR, 3.83; 95% CI, 2.53-5.79; p < 0.01), whereas IBS was significantly associated with erosive gastritis (aPR, 8.46; 95% CI, 4.89-14.67; p < 0.01) and duodenitis (aPR, 7.28; 95% CI, 3.64-14.59; p < 0.01). Red streaks tended to be associated with IBS (aPR, 1.96; 95% CI, 1.00-3.83; p = 0.05). Subjects with IBS were the most to complain of both upper and lower GI symptoms and psychological symptoms, followed by those with FC and controls. IBS subjects with erosive gastritis or duodenitis had significantly more complaints of stomachache and feeling stressed than those without erosive gastritis or duodenitis (54.5% vs. 18.8%; p = 0.03 and 66.7% vs. 25.0%; p = 0.01).

CONCLUSIONS

Subjects with FC and IBS had a variety of upper GI and psychological symptoms. In the upper GI endoscopic findings, corpus erosion and red streaks were associated with FC, and erosive gastritis, duodenitis, and possibly red streaks were associated with IBS.

Survey-Based Analysis of the Clinical Treatment Status of Irritable Bowel Syndrome in Korea

BACKGROUND

The quality-of-life of patients with irritable bowel syndrome is low; incorrect diagnosis/treatment causes economic burden and inappropriate consumption of medical resources. This survey-based study aimed to analyze the current status of irritable bowel syndrome treatment to examine differences in doctors' perceptions of the disease, and treatment patterns.

METHODS

From October 2019 to February 2020, the irritable bowel syndrome and Intestinal Function Research Study Group of the Korean Society of Neurogastroenterology and Motility conducted a survey on doctors working in primary, secondary, and tertiary healthcare institutions. The questionnaire included 37 items and was completed anonymously using the NAVER platform (a web-based platform), e-mails, and written forms.

RESULTS

A total of 272 doctors responded; respondents reported using the Rome IV diagnostic criteria (amended in 2016) for diagnosing and treating irritable bowel syndrome. Several differences were noted between the primary, secondary, and tertiary physicians' groups. The rate of colonoscopy was high in tertiary healthcare institutions. During a colonoscopy, the necessity of random biopsy was higher among physicians who worked at tertiary institutions. 'The patient did not adhere to the diet' as a reason for ineffectiveness using low-fermentable oligo-, di-, and mono-saccharides, and polyols diet treatment was higher among physicians in primary/secondary institutions, and 'There are individual differences in terms of effectiveness' was higher among physicians in tertiary institutions. In irritable bowel syndrome constipation predominant subtype, the use of serotonin type 3 receptor antagonist (ramosetron) and probiotics was higher in primary/secondary institutions, while serotonin type 4 receptor agonist was used more in tertiary institutions. In irritable bowel syndrome diarrhea predominant subtype, the use of antispasmodics was higher in primary/secondary institutions, while the use of serotonin type 3 receptor antagonist (ramosetron) was higher in tertiary institutions.

CONCLUSION

Notable differences were observed between physicians in primary/secondary and tertiary institiutions regarding the rate of colonoscopy, necessity of random biopsy, the reason for the ineffectiveness of low-fermentable oligo-, di-, and mono-saccharides, and polyols diet, and use of drug therapy in irritable bowel syndrome. In South Korea, irritable bowel syndrome is diagnosed and treated according to the Rome IV diagnostic criteria, revised in 2016.

Genome-wide multi-trait analysis of irritable bowel syndrome and related mental conditions identifies 38 new independent variants

BACKGROUND

Irritable bowel syndrome (IBS) is a chronic disorder of gut-brain interaction frequently accompanied by mental conditions, including depression and anxiety. Despite showing substantial heritability and being partly determined by a genetic component, the genetic underpinnings explaining the high rates of comorbidity remain largely unclear and there are no conclusive data on the temporal relationship between them. Exploring the overlapping genetic architecture between IBS and mental conditions may help to identify novel genetic loci and biological mechanisms underlying IBS and causal relationships between them.

METHODS

We quantified the genetic overlap between IBS, neuroticism, depression and anxiety, conducted a multi-trait genome-wide association study (GWAS) considering these traits and investigated causal relationships between them by using the largest GWAS to date.

RESULTS

IBS showed to be a highly polygenic disorder with extensive genetic sharing with mental conditions. Multi-trait analysis of IBS and neuroticism, depression and anxiety identified 42 genome-wide significant variants for IBS, of which 38 are novel. Fine-mapping risk loci highlighted 289 genes enriched in genes upregulated during early embryonic brain development and gene-sets related with psychiatric, digestive and autoimmune disorders. IBS-associated genes were enriched for target genes of anti-inflammatory and antirheumatic drugs, anesthetics and opioid dependence pharmacological treatment. Mendelian-randomization analysis accounting for correlated pleiotropy identified bidirectional causal effects between IBS and neuroticism and depression and causal effects of the genetic liability of IBS on anxiety.

CONCLUSIONS

These findings provide evidence of the polygenic architecture of IBS, identify novel genome-wide significant variants for IBS and extend previous knowledge on the genetic overlap and relationship between gastrointestinal and mental disorders.

Probiotics for the treatment of depression and its comorbidities: A systemic review

Depression is one of the most common psychiatric conditions, characterized by significant and persistent depressed mood and diminished interest, and often coexists with various comorbidities. The underlying mechanism of depression remain elusive, evidenced by the lack of an appreciate therapy. Recent abundant clinical trials and animal studies support the new notion that the gut microbiota has emerged as a novel actor in the pathophysiology of depression, which partakes in bidirectional communication between the gut and the brain through the neuroendocrine, nervous, and immune signaling pathways, collectively known as the microbiota-gut-brain (MGB) axis. Alterations in the gut microbiota can trigger the changes in neurotransmitters, neuroinflammation, and behaviors. With the transition of human microbiome research from studying associations to investigating mechanistic causality, the MGB axis has emerged as a novel therapeutic target in depression and its comorbidities. These novel insights have fueled idea that targeting on the gut microbiota may open new windows for efficient treatment of depression and its comorbidities. Probiotics, live beneficial microorganisms, can be used to modulate gut dysbiosis into a new eubiosis and modify the occurrence and development of depression and its comorbidities. In present review, we summarize recent findings regarding the MGB axis in depression and discuss the potential therapeutic effects of probiotics on depression and its comorbidities.

The neurobiology of irritable bowel syndrome

Irritable bowel syndrome (IBS) is the most prevalent disorder of brain-gut interactions that affects between 5 and 10% of the general population worldwide. The current symptom criteria restrict the diagnosis to recurrent abdominal pain associated with altered bowel habits, but the majority of patients also report non-painful abdominal discomfort, associated psychiatric conditions (anxiety and depression), as well as other visceral and somatic pain-related symptoms. For decades, IBS was considered an intestinal motility disorder, and more recently a gut disorder. However, based on an extensive body of reported information about central, peripheral mechanisms and genetic factors involved in the pathophysiology of IBS symptoms, a comprehensive disease model of brain-gut-microbiome interactions has emerged, which can explain altered bowel habits, chronic abdominal pain, and psychiatric comorbidities. In this review, we will first describe novel insights into several key components of brain-gut microbiome interactions, starting with reported alterations in the gut connectome and enteric nervous system, and a list of distinct functional and structural brain signatures, and comparing them to the proposed brain alterations in anxiety disorders. We will then point out the emerging correlations between the brain networks with the genomic, gastrointestinal, immune, and gut microbiome-related parameters. We will incorporate this new information into a systems-based disease model of IBS. Finally, we will discuss the implications of such a model for the improved understanding of the disorder and the development of more effective treatment approaches in the future.

Associations between postprandial symptoms, hydrogen and methane production, and transit time in irritable bowel syndrome

BACKGROUND

Abnormal oroanal transit time (OATT) and visceral hypersensitivity are key pathophysiological factors in irritable bowel syndrome (IBS). The lactulose nutrient challenge test (LNCT) has been developed to assess the postprandial symptoms and gut microbial fermentation. We aimed to investigate associations between OATT, rectal sensitivity, and LNCT in IBS patients.

METHODS

We included 263 IBS patients from two study cohorts, where the link between pathophysiology and symptoms was investigated. During the LNCT, severity of postprandial symptoms was graded, and breath hydrogen/methane concentrations were measured after ingestion of a combined lactulose nutrient drink every 15 min for 4 h. The patients underwent rectal sensitivity (rectal barostat) and OATT (radiopaque markers) investigations. Comorbid conditions (functional dyspepsia, anxiety, depression, and somatization) were assessed with questionnaires.

KEY RESULTS

After controlling for comorbid conditions, rectal sensitivity was associated with abdominal pain (p < 0.05), and more rapid OATT was associated with higher severity of abdominal discomfort, rumbling, nausea, and urgency (p < 0.05 for all) both pre- and post-prandially. Postprandial nausea, urgency, and abdominal pain changed differently over time depending on OATT (p < 0.05 for all). OATT, but not rectal sensitivity, was associated with hydrogen and methane concentrations (p = 0.002 for both). Trajectories over time of postprandial symptoms and exhaled hydrogen/methane concentrations were correlated with different correlations depending on OATT.

CONCLUSION AND INFERENCES

This study highlights the importance of oroanal transit and hydrogen and methane production in the pathophysiology of IBS and increases our understanding of pathophysiological factors involved in postprandial symptom generation. Treatments targeting oroanal transit and hydrogen and methane production may improve specific postprandial symptoms.

Symptom management needs of patients with irritable bowel syndrome and concurrent anxiety and/or depression: A qualitative study

AIMS

To understand the experiences and needs of symptom management among individuals with irritable bowel syndrome and concurrent symptoms of anxiety and/or depression.

DESIGN

This study used a qualitative descriptive research design.

METHODS

Individuals with a diagnosis of irritable bowel syndrome and concurrent symptoms of anxiety and/or depression participated were recruited through an online ResearchMatch and a listserv. Semi-structured interviews focused on symptoms and experiences with symptom management interventions conducted from June to August 2020. Interviews were transcribed and data were analysed based on thematic analysis.

RESULTS

Twelve individuals participated in this study; all reported current irritable bowel syndrome and anxiety/depression symptoms. The data analysis cumulated with three themes related to symptom management: (a) irritable bowel syndrome negatively impacts physical and mental well-being; (b) a trial and error approach to symptom management; and (c) challenges with healthcare professionals supporting symptom management including negative interactions with healthcare professionals and lack of nutritional expertize and support.

CONCLUSION

There is a need for individualized approaches which consider patients' current symptoms of anxiety and depression, previous experiences with the trial-and-error process and consideration for intervention delivery methods.

IMPACT

There is a limited qualitative research focusing on the experiences of individuals with irritable bowel syndrome and concurrent symptoms of anxiety and/or depression. This research highlights the need for individualized approaches to enhance symptom management that acknowledges patients' psychological state and past negative experiences with providers and prior dietary regimens.

Negative experiences with public bathrooms and chronic illness-related shame

INTRODUCTION

The use of public bathrooms is a challenge for everyone, but especially for those who are affected by a bathroom-dependent condition. Being dependent on bathrooms is linked with different negative emotions. One of them is a clinically relevant emotion: shame associated with the chronic condition.

MATERIALS AND METHODS

In a cross-sectional survey study (n = 193) of people who suffer a bathroom-dependent condition we asked about health conditions, well-being, and shame related to chronic condition outcomes.

RESULTS

We show a link between negative public bathroom experiences, and diminished well-being and feelings of shame related to chronic illness. We found that this relationship between negative experiences with public bathrooms and shame is not specific to the different conditions.

CONCLUSION

We conclude that the negative experiences which people with different gastrointestinal illnesses face is an environmental stressor associated with more embarrassment as a result of the condition suffered.

Hypnotherapy and IBS: Implicit, long-term stress memory in the ENS?

The association between irritable bowel syndrome (IBS) and psychiatric and mood disorders may be more fundamental than was previously believed. Prenatal, perinatal, postnatal, and early-age conditions can have a key role in the development of IBS. Subthreshold mental disorders (SMDs) could also be a significant source of countless diverse diseases and may be a cause of IBS development. We hypothesize that stress-induced implicit memories may persist throughout life by epigenetic processes in the enteric nervous system (ENS). These stress-induced implicit memories may play an essential role in the emergence and maintenance of IBS. In recent decades, numerous studies have proven that hypnosis can improve the primary symptoms of IBS and also reduce noncolonic symptoms such as anxiety and depression and improve quality of life and cognitive function. These significant beneficial effects of hypnosis on IBS may be because hypnosis allows access to unconscious brain processes.

Psychological Characteristics and Quality of Life of Patients with Upper and Lower Functional Gastrointestinal Disorders

Background: This study aimed to identify the differences in the psychological characteristics of the anatomical location of functional gastrointestinal disorders (FGIDs) and the factors that influence the quality of life (QOL). Methods: Altogether, 233 patients with FGIDs were classified into the upper gastrointestinal disorder (UGID; n = 175) group and the lower gastrointestinal disorder group (LGID; n = 58). Psychological characteristics and QOL were evaluated using the validated questionnaires. Results: The LGID group demonstrated higher scores in ‘emotional depression’ than the UGID group in depressive symptoms (t = −3.031, p < 0.01). A significant difference was observed between groups in ‘significant others’ in social supports (t = 2.254, p < 0.05). Significant differences were observed between the groups in hardiness (t = 2.259, p < 0.05) and persistence (t = 2.526, p < 0.05) in resilience, while the LGID group demonstrated significantly lower scores than the UGID group in ‘negative affectivity’ in type-D personality (t = −1.997, p < 0.05). Additionally, the LGID group demonstrated lower QOL than the UGID group (t = 2.615, p < 0.05). The stepwise regression analysis on QOL involved depression, resilience, social support, and childhood trauma, which accounted for 48.4% of the total QOL explanatory variance. Conclusions: Psychological characteristics and QOL significantly differed when FGIDs were classified according to anatomical location. Thus, psychological interventions customized for each type of FGIDs may be necessary for effective treatment.

The Chemo-Gut Study: A Cross-Sectional Survey Exploring Physical, Mental, and Gastrointestinal Health Outcomes in Cancer Survivors

Background

Cancer treatments, such as chemotherapy, may adversely affect gastrointestinal (GI), physical and mental health in survivors of cancer.

Objective

This study investigated associations between GI, mental and physical health outcomes, and cancer treatment-related variables, such as chemotherapy, in adult cancer survivors.

Methods

A one-time cross-sectional survey with patient-reported outcomes was used. Cancer survivors (N = 317) aged ≥18 years, living in Canada, who completed cancer treatments were included. Descriptive statistics, correlation, and linear regression analyses are reported.

Results

Mean age at diagnosis was 40.90 ± 15.40 years. Most survivors received chemotherapy (86.1%). Persistent GI symptoms include constipation (53.6%), diarrhea (50.5%), and bloating/pain (54.9%). Mean GI symptom duration was 30.53 ± 33.42 months. Severity of GI symptom interference was moderate to extreme for 51.9% of survivors. Compared to normative values of 50 in healthy people, survivors scored poorer for mental health (M = 42.72 ± 8.16) and physical health (M = 45.55 ± 7.93), and reported more belly pain (M = 56.10 ± 8.58), constipation (M = 54.38 ± 6.81), diarrhea (M = 55.69 ± 6.77), and gas/bloating (M = 56.08 ± 8.12). Greater GI symptom severity was associated with poorer mental and physical health (P < .01). Chemotherapy was associated with increased belly pain (B = 4.83, SE = 1.65, P < .01) and gas/bloating (B = 3.06, SE = 1.45, P = .04).

Conclusion

We provide novel evidence that many cancer survivors experience chronic, moderate to severe GI symptoms lasting for years after cancer treatment, which are associated with worse mental and physical health. Chemotherapy is associated with specific GI symptoms. Integrative therapies are needed to address GI symptoms in cancer survivors.

Psychotherapy appears to improve symptoms of functional dyspepsia and anxiety: systematic review with meta-analysis

This systematic review and meta-analysis examined the efficacy of psychotherapy on symptoms of functional dyspepsia, anxiety, depression and quality of life. We searched Medline, Embase, PsycINFO, Emcare, Ovid Nursing, CINAHL, Cochrane Library, Informit Health Collection and ClinicalTrials.gov on 2 July 2021. Randomised controlled trials that compared psychotherapy to non-psychotherapy interventions in adults with functional dyspepsia were included. Meta-analyses were conducted (using Hedges's g) under random effects models. Overall, 1,575 records were identified after duplicates were removed, with nine randomised controlled trials (n = 786) included. Preliminary meta-analyses showed that psychotherapy outperformed control conditions at post-test and follow-up on functional dyspepsia symptom severity and anxiety symptoms, but no differences emerged for depressive symptoms. The qualitative synthesis showed psychotherapy's promise in improving quality of life in functional dyspepsia. Psychotherapy might have a small to moderate effect on functional dyspepsia symptoms and anxiety at short- and long-term. However, conclusions are limited by the small number of trials with a high risk of bias.

Two Gold Kiwifruit Daily for Effective Treatment of Constipation in Adults-A Randomized Clinical Trial

Chronic constipation is highly prevalent worldwide and may be managed with two green or three gold kiwifruit daily. It is unknown whether a smaller standard serve of gold kiwifruit (two daily) is as effective in constipation management. The study aimed to improve chronic constipation with two gold kiwifruit and psyllium in lieu of a placebo daily over four weeks. Adult participants (18-65 years) with functional constipation (FC, n = 11), constipation-predominant irritable bowel syndrome (IBS-C, n = 13), and healthy controls (n = 32) were block-randomized to the treatment order: gold kiwifruit (2/day) or psyllium (fiber-matched, 7.5 g/day) for four weeks, followed by four weeks washout before crossover. Outcomes included alterations of Gastrointestinal Symptom Rating Scale (GSRS) domains and weekly complete spontaneous bowel movements (CSBM) as part of a larger study. Both interventions reduced GSRS constipation domain scores in all subjects compared to baseline values (p = 0.004). All participants reported significantly more weekly CSBM (p = 0.014). Two gold kiwifruit decreased straining (p = 0.021). Two gold kiwifruit daily are as effective as fiber-matched psyllium in treating constipation in adults and should be considered as a treatment option.

Irritable bowel syndrome and its associated factors among Jordanian medical students: A cross-sectional study

Very scarce studies investigated the prevalence of irritable bowel syndrome (IBS) and its correlates in the Middle East, particularly in college students. We aimed to investigate the prevalence of IBS and its associated factors among Jordanian medical students. We conducted a cross-sectional study at 2 medical facilities in northern Jordan. We recruited 1135 medical students. Participants completed an anonymous questionnaire addressing sociodemographic, lifestyle, and clinical characteristics. An interview questionnaire was used to diagnose IBS according to the Rome III criteria. Comorbid anxiety and depression were diagnosed by using the Hospital Anxiety and Depression Scale. Of the 1135 completed questionnaires, 1094 (94%) had complete data. The prevalence of IBS in our sample was 30.9%. Binary logistic regression analysis of factors associated with IBS indicated having a family history of IBS as a strong predictor of the disease (odds ratio [OR]: 8.09; 95% confidence interval [CI]: 5.84-11.19). Students in the second and third years of their study had ORs of approximately 4 (95% CI: 2.20-6.54) and 3 (95% CI: 1.70-5.30) for suffering from IBS, respectively, compared with those in the first year (P = .001). Increased anxiety score (OR: 1.88; 95% CI: 1.30-2.71), poor sleep quality (OR: 1.76; 95% CI: 1.13-2.76), female sex (OR: 1.59; 95% CI: 1.14-2.20), and living in a school dormitory (OR: 1.35; 95% CI: 1.00-1.84) were significantly associated with IBS (P < .05). IBS is a highly prevalent disorder among Jordanian medical students, with several factors associated with its occurrence.

Risk Factors for Self-reported Irritable Bowel Syndrome With Prior Psychiatric Disorder: The Lifelines Cohort Study

Background/Aims

The role of psychiatric disorder in irritable bowel syndrome (IBS) is not clear. This study aims to assess whether individuals who have psychiatric disorder prior to IBS onset differ in their risk factors from the remainder.

Methods

The prospective, population-based Lifelines cohort study includes 132 922 adults without prior IBS or taking IBS medication at baseline. Baseline data included socio-demographic status, physical and psychiatric disorders, psycho-social and behavioral variables. At follow-up (mean 2.4 years later) new onsets of IBS were recorded by self-report. The predictors of new onsets of IBS were assessed using logistic regression; participants with and without prior psychiatric disorders were analyzed separately.

Results

At follow-up 1507 (1.1%) participants reported new onset IBS. Of these, 27% reported prior psychiatric disorder. Predictors of IBS in this group were 2 or more psychiatric disorders (OR, 2.74; 95% CI, 1.3-5.6), female sex, proton pump inhibitors, numerous bodily symptoms, impaired sleep, low BMI and negative health perception. These variables, except psychiatric disorders and BMI, also predicted IBS in those without prior psychiatric disorder but, in this group, gallstones, asthma, fibromyalgia, reported allergies, impairment through bodily pain, and frequent healthcare were also predictors.

Conclusions

Despite its limitations this study suggests that prior psychiatric disorder is an important risk factor in a quarter of IBS onsets. Negative health perception and multiple bodily symptoms are associated with all IBS onsets in line with the cognitive-behavior model of IBS. Prior psychiatric disorder may predict an optimal response to psychiatric treatment. Further studies could usefully study mechanisms linking IBS to prior psychiatric disorder.

Effects and Mechanisms of Acupuncture on Diarrhea-Predominant Irritable Bowel Syndrome: A Systematic Review

Background

Irritable bowel syndrome (IBS) is a common disorder of gut-brain interaction with challenging treatment. According to evidence-based studies, acupuncture is likely to be a promising therapy and subservient adjunct for IBS. Mechanism study of acupuncture based on related clinical trials of high quality, nevertheless, is still vacant.

Aim

This study aims to assess the results and qualities of current clinical evidence and conclude the relevant pathophysiological mechanisms and therapeutic effects of acupuncture on IBS with diarrhea (IBS-D).

Methods

Literature from four databases, namely, PubMed, Cochrane Library, EMBASE, and Web of Science, was systematically searched to obtain eligible randomized controlled trials (RCTs), which contained mechanism research of acupuncture treatment in IBS-D patients. Two independent reviewers completed data extraction and quality evaluation using the RevMan 5.4.1 software.

Results

Ten trials that covered 19 items related to mechanism research were included in this review. Acupuncture was reported to improve IBS-D symptoms and quality of life, with positive effects in regulating brain-gut peptides, cerebral activities, neuroendocrine functions, psychological state, and inflammatory GI and hypersensitive intestinal tracts.

Conclusion

Acupuncture has potential influence on pathophysiology alterations such as regulating brain-gut peptides, altering cerebral connectivity and activity, promoting neuroendocrine functions and mental state, and mitigating inflammation as well as hypersensitivity of bowels in IBS-D patients, but further studies of high quality are still necessary.

Systematic Review Registration

[https://www.crd.york.ac.uk/PROSPERO], identifier [CRD42022320331].

Oxytocin: Narrative Expert Review of Current Perspectives on the Relationship with Other Neurotransmitters and the Impact on the Main Psychiatric Disorders

Is a cyclic neuropeptide produced primarily in the hypothalamus and plays an important neuromodulatory role for other neurotransmitter systems, with an impact on behavior, response to danger, stress, and complex social interactions, such as pair bonding and child care. This narrative expert review examines the literature on oxytocin as a brain hormone. We focused on oxytocin structure, distribution, genetics, and the oxytocin receptor system, as well as the relationship of oxytocin with other neurotransmitters and the resulting impacts on the main psychiatric disorders. Oxytocin levels have been correlated over time with mental illness, with numerous studies focusing on oxytocin and the pathophysiology of the main psychiatric disorders, such as autism, schizophrenia, personality disorders, mood, and eating disorders. We highlight the role oxytocin plays in improving symptoms such as anxiety, depression, and social behavior, as the literature suggests. Risk factors and causes for psychiatric disorders range from genetic to environmental and social factors. Oxytocin could impact the latter, being linked with other neurotransmitter systems that are responsible for integrating different situations during the development phases of individuals. Also, these systems have an important role in how the body responds to stressors or bonding with others, helping with the creation of social support groups that could speed up recovery in many situations. Oxytocin has the potential to become a key therapeutic agent for future treatment and prevention strategies concerning the main psychiatric disorders.

Abdominal Pain Severity Is Mainly Associated with Bloating Severity in Patients with Functional Bowel Disorders and Functional Abdominal Pain

PURPOSE

Abdominal pain is a cardinal sign of functional bowel disorders (FBD), in favor of irritable bowel syndrome (IBS). However, the determinants of abdominal pain severity (APS) are unknown. The present study aimed to search the relationships between APS and demographic, psychological, and clinical parameters in tertiary care FBD outpatients.

PATIENTS AND METHODS

In this retrospective study, we included 2043 new outpatients with FBD or functional abdominal pain. They fulfilled the Rome III questionnaire, psychological evaluation, and four 10-points Likert scale for the perceived severity of constipation, diarrhea, bloating, and abdominal pain. Linear regression was performed for each phenotype to model the severity of abdominal pain with demographic, psychological parameters, and symptoms severity.

RESULTS

APS was positively associated with bloating severity in all phenotypes, but APS was also associated with other variables according to gender and phenotype. APS was negatively associated with age and positively with depression, constipation severity, and diarrhea severity in female patients. In male patients, APS was associated with state anxiety, constipation severity, and diarrhea severity. APS severity was associated with bloating severity and transit severity in IBS patients, while in non-IBS patients, APS was only associated with bloating severity.

CONCLUSION

Perceived abdominal pain severity is always associated with perceived bloating severity in FBD and FAP patients.

Post-Infectious Irritable Bowel Syndrome after an Epidemic of Gastroenteritis in South of Iran

Background: Irritable bowel syndrome (IBS) is a chronic disabling condition without a well-defined etiology. Infectious gastroenteritis (IGE) has been linked to this syndrome. There are few data from Iran on this association. Methods: In August 2018, an epidemic of IGE caused by Escherichia coli occurred in a village in the west of Shiraz in southern Iran. One year after this epidemic, the occurrence of IBS was surveyed in those who suffered from IGE based on Rome IV criteria in that village. Results: Of 179 patients included in the present study, 17 patients (9.5%) had post-infectious (PI)-IBS. There was no difference in age, sex, antibiotic use, hematochezia, duration of infectious diarrhea, fever, and weight loss at the time of IGE between those with and without PI-IBS. Conclusion: PI-IBS is common after IGE, but no risk factor for its development was found in this study.

The relationships between IBS and perceptions of physical and mental health-a Norwegian twin study

BACKGROUND AND AIMS

Poor quality of life is a main complaint among individuals with irritable bowel syndrome (IBS). Self-rated health (SRH) is a powerful predictor of clinical outcomes, and also reflects psychological and social aspects of life and an overall sense of well-being. This population-based twin study evaluates how IBS affects ratings of physical and mental health, and influences perceptions of hindrance of daily activity by physical or mental health. Further, we examine how IBS is related to these SRH measures.

METHODS

The sample included 5288 Norwegian twins aged 40-80, of whom 575 (10.9%) suffer from IBS. Hierarchical regressions were used to estimate the impact of IBS on perceptions of health, before and after accounting for other chronic physical and mental health conditions. Two dimensions of SRH, physical and mental, and two aspects of functional limitations, the extent to which physical or mental health interferes with daily activities, were included as outcomes in separate models. Co-twin control analyses were used to explore whether the relationships between IBS and the four measures of SRH are causal, or due to shared genetic or shared environment effects.

RESULTS

IBS was an independent predictor of poor self-rated physical health (OR = 1.82 [1.41; 2.33]), the size of this effect was comparable to that predicted by chronic somatic conditions. However, in contrast to somatic diseases, IBS was associated with the perception that poorer ratings of mental health (OR = 1.45 [1.02; 2.06]), but not physical health (OR = 1.23 [0.96; 1.58]), interfered with daily activity. The co-twin control analyses suggest that causal mechanisms best explain the relationships between IBS with self-rated physical health and with hindrance of daily activities. In contrast, the relationship between IBS and self-rated mental health was consistent with shared genetic effects.

CONCLUSION

IBS is predictive of poor self-rated physical health. The relationship between IBS and self-rated mental health is best explained by shared genetic effects which might partially explain why mental health interferes with daily activity to a larger degree among those with IBS.

Depression and anxiety screening in emergency department patients with recurrent abdominal pain: An evidence synthesis for a clinical practice guideline

BACKGROUND

Recurrent abdominal pain in the emergency department (ED) might represent an opportunity for screening of depression and/or anxiety.

METHODS

We systematically searched five databases for studies evaluating the effect of screening for depression and/or anxiety in ED patients with recurrent and undifferentiated abdominal pain. Given paucity of direct evidence, we also searched for indirect evidence including studies that assessed prevalence of depression and/or anxiety in EDs (not necessarily recurrent abdominal pain), diagnostic accuracy of screening tools, effectiveness of screening in other settings, and outcomes such as repeat ED visits of patients with abdominal pain who were screened in the ED. Two methodologists evaluated certainty in the evidence using the GRADE approach.

RESULTS

A total of 4,337 citations were reviewed, and zero studies were found on the effect of screening in patients with recurrent and undifferentiated abdominal pain in the ED. A total of 35 studies were included as relevant indirect evidence. In studies of ED patients with abdominal pain, depression ranged from 10% to 29%, while anxiety ranged from 18% to 50%. False positives appear to be an issue given relatively low specificity of screening tools. One randomized trial including ED patients with vague symptoms evaluated the effect of depression screening on a composite outcome of depression recognition, psychiatric consultation, or referral by the emergency physician (risk ratio = 1.49, 95% confidence interval [CI] = 0.49 to 4.53, very low certainty). One study reported that patients with undifferentiated abdominal pain who screened positive for depression have had increased ED recidivism (odds ratio = 3.17, 95% CI = 1.14 to 8.85, very low certainty).

CONCLUSIONS

We were unable to identify any evidence that confirms that depression or anxiety screening in ED patients with recurrent and undifferentiated abdominal pain improves outcomes or changes management downstream.

Abnormal Default Mode Network Homogeneity in Major Depressive Disorder With Gastrointestinal Symptoms at Rest

Background

Gastrointestinal (GI) symptoms are prominent in many patients with major depressive disorder (MDD). However, it remains unclear whether MDD patients with GI symptoms have brain imaging alterations in the default mode network (DMN) regions.

Methods

A total of 35 MDD patients with GI symptoms, 17 MDD patients without GI symptoms, and 28 healthy controls (HCs) were recruited. All participants underwent resting-state functional magnetic resonance imaging scans. Network homogeneity (NH) and support vector machine (SVM) methods were used to analyze the imaging data.

Results

Gastrointestinal group showed higher 17-item Hamilton Rating Scale for Depression total scores and factor scores than the non-GI group. Compared with the non-GI group and HCs, the GI group showed decreased NH in the right middle temporal gyrus (MTG) and increased NH in the right precuneus (PCu). The SVM results showed that a combination of NH values of the right PCu and the right MTG exhibited the highest accuracy of 88.46% (46/52) to discriminate MDD patients with GI symptoms from those without GI symptoms.

Conclusion

Major depressive disorder patients with GI symptoms have more severe depressive symptoms than those without GI symptoms. Distinctive NH patterns in the DMN exist in MDD patients with GI symptoms, which can be applied as a potential brain imaging marker to discriminate MDD patients with GI symptoms from those without GI symptoms.

Antibiotics, gut microbiota, and irritable bowel syndrome: What are the relations?

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder in which recurrent abdominal pain is associated with defecation or a change in bowel habits (constipation, diarrhea, or both), and it is often accompanied by symptoms of abdominal bloating and distension. IBS is an important health care issue because it negatively affects the quality of life of patients and places a considerable financial burden on health care systems. Despite extensive research, the etiology and underlying pathophysiology of IBS remain incompletely understood. Proposed mechanisms involved in its pathogenesis include increased intestinal permeability, changes in the immune system, visceral hypersensitivity, impaired gut motility, and emotional disorders. Recently, accumulating evidence has highlighted the important role of the gut microbiota in the development of IBS. Microbial dysbiosis within the gut is thought to contribute to all aspects of its multifactorial pathogenesis. The last few decades have also seen an increasing interest in the impact of antibiotics on the gut microbiota. Moreover, antibiotics have been suggested to play a role in the development of IBS. Extensive research has established that antibacterial therapy induces remarkable shifts in the bacterial community composition that are quite similar to those observed in IBS. This suggestion is further supported by data from cohort and case-control studies, indicating that antibiotic treatment is associated with an increased risk of IBS. This paper summarizes the main findings on this issue and contributes to a deeper understanding of the link between antibiotic use and the development of IBS.

Habitual Green Kiwifruit Consumption Is Associated with a Reduction in Upper Gastrointestinal Symptoms: A Systematic Scoping Review

Kiwifruit have known positive effects on digestion. During clinical intervention trials using kiwifruit to improve constipation, upper gastrointestinal (GI) symptoms such as abdominal discomfort and pain, indigestion, and reflux were also alleviated. We aimed to evaluate the evidence for upper GI symptom relief by kiwifruit in clinical trials on participants with functional constipation (FC), irritable bowel syndrome with constipation (IBS-C), and healthy participants, and to elucidate which symptoms may be relieved and whether a difference exists between the effects of gold and green kiwifruit. We executed a systematic scoping review of 3 electronic databases from 1947 through January 2021 to identify clinical trials that reported effects of green or gold kiwifruit or kiwifruit compounds on upper GI symptoms as secondary outcomes in healthy participants or participants with FC or IBS-C. Studies were divided into those using the Gastrointestinal Symptom Rating Scale (GSRS) and those using alternative measurement tools. GSRS outcomes were pooled and statistically analyzed; non-GSRS outcomes were summarized. We identified 12 clinical trials with a total of 661 participants (124 controls, 537 receiving intervention) providing evidence for symptom relief of upper GI symptoms by kiwifruit intake. Only 5 of the 12 clinical trials used the GSRS to assess upper GI symptom relief. We found good evidence that green kiwifruit may reduce abdominal discomfort and pain, and some evidence that kiwifruit consumption may attenuate indigestion. Pooled GSRS outcome analysis indicates an average reduction of -0.85 (95% CI: -1.1, -0.57; Z = 6.1) in abdominal pain scores and -0.33 (95% CI: -0.52, -0.15; Z = -3.5) in indigestion scores with habitual kiwifruit consumption. While the number of studies reporting on upper GI symptom relief with a comparable measurement is limited, there is consistent evidence for the efficacy of kiwifruit on upper GI symptom relief. More research to strengthen the evidence is recommended.

Pathophysiological Commonality Between Irritable Bowel Syndrome and Metabolic Syndrome: Role of Corticotropin-releasing Factor-Toll-like Receptor 4-Proinflammatory Cytokine Signaling

Irritable bowel syndrome (IBS) displays chronic abdominal pain with altered defecation. Most of the patients develop visceral hypersensitivity possibly resulting from impaired gut barrier and altered gut microbiota. We previously demonstrated that colonic hyperpermeability with visceral hypersensitivity in animal IBS models, which is mediated via corticotropin-releasing factor (CRF)-Toll-like receptor 4 (TLR4)-proinflammatory cytokine signaling. CRF impairs gut barrier via TLR4. Leaky gut induces bacterial translocation resulting in dysbiosis, and increases lipopolysaccharide (LPS). Activation of TLR4 by LPS increases the production of proinflammatory cytokines, which activate visceral sensory neurons to induce visceral hypersensitivity. LPS also activates CRF receptors to further increase gut permeability. Metabolic syndrome (MS) is a cluster of cardiovascular risk factors, including insulin resistance, obesity, dyslipidemia, and hypertension, and recently several researchers suggest the possibility that impaired gut barrier and dysbiosis with low-grade systemic inflammation are involved in MS. Moreover, TLR4-proinflammatory cytokine contributes to the development of insulin resistance and obesity. Thus, the existence of pathophysiological commonality between IBS and MS is expected. This review discusses the potential mechanisms of IBS and MS with reference to gut barrier and microbiota, and explores the possibility of existence of pathophysiological link between these diseases with a focus on CRF, TLR4, and proinflammatory cytokine signaling. We also review epidemiological data supporting this possibility, and discuss the potential of therapeutic application of the drugs used for MS to IBS treatment. This notion may pave the way for exploring novel therapeutic approaches for these disorders.

Impact of COVID-19 on Individuals With Irritable Bowel Syndrome and Comorbid Anxiety and/or Depression

GOALS

The goal of this study was to describe the influence of the COVID-19 pandemic on ability to engage in activities and the influence on psychological distress and gastrointestinal symptoms among individuals with irritable bowel syndrome (IBS) and comorbid anxiety and/or depression.

BACKGROUND

Individuals with IBS and comorbid anxiety and/or depression report increased symptoms and decreased quality of life compared with individuals with IBS alone. The current COVID-19 pandemic has the potential to further influence symptoms among individuals with IBS and comorbid anxiety and/or depression.

STUDY

Individuals who met the Rome-IV IBS criteria and reported mild to severe anxiety and/or depression were included. Participants completed an online survey with questions about anxiety, depression, impact of COVID on activities and symptoms, and demographics.

RESULTS

Fifty-five individuals participated in the study. The COVID-19 pandemic most commonly influenced their ability to spend time with friends and family, shop for certain types of food, and access health care. Participants also reported increased stress (92%), anxiety (81%), and depressive symptoms (67%). Finally, around half the sample reported increases in abdominal pain (48%), diarrhea (45%), or constipation (44%).

CONCLUSIONS

The COVID-19 pandemic is related to self-reported increases in psychological distress and gastrointestinal symptoms among individuals with IBS and comorbid anxiety and/or depression. Additional research is needed to intervene on these symptoms.

Associations of neurotransmitters and the gut microbiome with emotional distress in mixed type of irritable bowel syndrome

Evidence highlights the comorbidity between emotional distress and irritable bowel syndrome (IBS) through the gut-brain axis. However, the underlying mechanism is largely unknown. Thus, the present study aimed to evaluate the associations among neurotransmitter levels and the gut microbiome profiles in persons with IBS and emotional distress. In this nested case-controlled study, emotional symptoms, including anxiety and depressive symptoms, were evaluated in 40 persons with IBS and 20 healthy controls (HC). Plasma neurotransmitters levels (serotonin and norepinephrine) and the gut microbiome profile of the collected fecal samples were examined. Emotional distress and microbiome profile were significantly different between IBS and HC groups. Lower but not significant neurotransmitters' levels (serotonin and norepinephrine) were observed in the IBS group compared to the HC. A negative correlation was found between norepinephrine levels and alpha diversity (Shannon and Simpson indices) in the IBS group. Moreover, serotonin levels were positively associated with the abundance of Proteobacteria, and norepinephrine were positively correlated with Bacteroidetes, but negatively associated with Firmicutes phylum. The present study demonstrated alteration in the gut microbiome between persons with IBS and emotional distress compared to HC. The correlations between plasma neurotransmitters and the gut microbiome suggest that the gut microbiome may impact the regulation of neurotransmitters.

The Role of Copper and Zinc in Irritable Bowel Syndrome: A Mendelian Randomization Study

Irritable bowel syndrome (IBS) has been associated with copper and zinc imbalance and a zinc-deficient diet. Mendelian randomization was used in this study to evaluate if genetically determined copper and zinc levels play a causal role in the development of IBS. Three single-nucleotide polymorphisms (SNPs; rs1175550, rs2769264, and rs2769270) associated with erythrocyte copper levels, and 3 SNPs associated with erythrocyte zinc levels (rs11638477, rs1532423, and rs2120019) in the Australian Twin Study (1993-1996 and 2001-2005) were used as instrumental variables for levels of these metals. The association of these SNPs with IBS was tested using summary statistics computed from data on 340,331 individuals from the UK Biobank, 5,548 of whom had IBS (2006-2010). Genetically predicted high serum copper levels were associated with a lower risk of IBS (odds ratio = 0.89; 95% confidence interval: 0.80, 0.98). Genetically predicted, high serum zinc levels were nonsignificantly associated with a higher risk of IBS (odds ratio = 1.06; 95% confidence interval: 0.95, 1.18). Sensitivity analysis did not suggest the presence of pleiotropy. These results suggest that high erythrocyte copper levels may be protective against IBS development. Targeting higher levels, therefore, may provide an avenue to reduce the likelihood of IBS development in high-risk individuals.

Lithium carbonate alleviates colon inflammation through modulating gut microbiota and Treg cells in a GPR43-dependent manner

BACKGROUND

Recent evidence suggests that neuropsychiatric stabilizers have a place in resolving gastrointestinal disorders. Lithium carbonate (LC) is one of the most commonly used drugs for bipolar disorder clinically. Here, we estimate the therapeutic function of LC against colitis and investigate the mechanism of intestinal flora and metabolism modulation.

METHODS

A colitis model was constructed by continuously administering 2.5% dextran sodium sulfate (DSS) solution daily for 7 days. Analysis of gut microbiota was carried out by 16S rRNA gene high-throughput sequencing. Spectrum antibiotic cocktail (ABX) and faecal microbiota transplantation (FMT) were employed to evaluate the protective effect of intestinal flora. Colonic Treg cells and related immune responses were detected by flow cytometry.

RESULTS

LC treatment significantly alleviated colon inflammation by regulating gut microbial diversity and altering flora composition. Notably, LC treatment upregulated short-chain fatty acid (SCFA)-producing bacteria, especially Akkermansia muciniphila (A. muciniphila), and transformed metabolite SCFA profiles. LC activated anti-inflammatory Treg cell responses in colonic lamina propria (LP) in a G-protein coupled receptor 43 (GPR43)-dependent mechanism. ABX, FMT and single bacteria gavage experiments were conducted to confirm the above mechanism.

CONCLUSIONS

As an intestinal microbiome and metabolite modulator, LC alleviates colon inflammation in a GPR43-dependent manner through activating Treg cell responses. Therefore, the therapeutic strategy of the microbiome-metabolite-immune axis, as observed in the A. muciniphila-SCFA-Treg cell axis in our study, might provide a new direction for the treatment of IBD.

The Role of the Gut Microbiota in the Development and Progression of Major Depressive and Bipolar Disorder

A growing number of studies in rodents indicate a connection between the intestinal microbiota and the brain, but comprehensive human data is scarce. Here, we systematically reviewed human studies examining the connection between the intestinal microbiota and major depressive and bipolar disorder. In this review we discuss various changes in bacterial abundance, particularly on low taxonomic levels, in terms of a connection with the pathophysiology of major depressive and bipolar disorder, their use as a diagnostic and treatment response parameter, their health-promoting potential, as well as novel adjunctive treatment options. The diversity of the intestinal microbiota is mostly decreased in depressed subjects. A consistent elevation of phylum Actinobacteria, family Bifidobacteriaceae, and genus Bacteroides, and a reduction of family Ruminococcaceae, genus Faecalibacterium, and genus Roseburia was reported. Probiotics containing Bifidobacterium and/or Lactobacillus spp. seemed to improve depressive symptoms, and novel approaches with different probiotics and synbiotics showed promising results. Comparing twin studies, we report here that already with an elevated risk of developing depression, microbial changes towards a “depression-like” microbiota were found. Overall, these findings highlight the importance of the microbiota and the necessity for a better understanding of its changes contributing to depressive symptoms, potentially leading to new approaches to alleviate depressive symptoms via alterations of the gut microbiota.

The Use of Prebiotic and Probiotic Interventions for Treating Gastrointestinal and Psychosocial Health Symptoms in Cancer Patients and Survivors: A Systematic Review

BACKGROUND

Cancer treatments can cause significant gastrointestinal (GI) health issues, and negatively affect patient's psychosocial health and quality of life (QOL). Novel, integrative strategies using prebiotics and probiotics have been explored for treating adverse cancer treatment-related side effects. We evaluated the current literature for interventions using prebiotics or probiotics specifically to treat GI and psychosocial health issues in cancer patients and survivors.

METHODS

Five databases (PubMed, MEDLINE (Ovid), CINHAL, PsychINFO, Web of Science) were searched for studies with prebiotic or probiotic interventions where GI and/or psychosocial health outcomes were measured in adult cancer patients and survivors, and published before September 12th 2021.

RESULTS

Twelve studies (N = 974 participants) meeting the inclusion criteria were identified (randomized controlled trials [n = 10], single-group pre-post studies [n = 2]). Ten studies were conducted with patients on active cancer treatment, and 2 studies treated patients after anti-cancer therapies. Three studies used prebiotics, 7 studies used probiotics, and 2 studies used a combination therapy. The most commonly used probiotic strains were from the Lactobacillus genus. There was minimal evidence for prebiotics to improve GI or psychosocial health. Probiotics were associated with significant improvements in abdominal pain (n = 2), gas/bloating (n = 2), and especially diarrhea (n = 5), and with improvements in anxiety (n = 1), depression (n = 1), fatigue (n = 1), and QOL (n = 2).

CONCLUSIONS

Studies specifically examining effects of prebiotics and probiotics on GI and psychosocial health outcomes are scarce. Probiotic intervention may improve some GI symptoms in cancer patients, and QOL in survivors. Controlled trials that consistently include GI and psychosocial health outcomes are needed.