The Prevalence and Incidence of Irritable Bowel Syndrome and Inflammatory Bowel Disease in Depression and Bipolar Disorder: A Systematic Review and Meta-Analysis

Association between psychiatric disorders and irritable bowel syndrome: A bidirectional Mendelian randomization study

OBJECTIVE

Previous studies have suggested that irritable bowel syndrome (IBS) is strongly associated with psychiatric disorders. However, it is unclear whether this association is causal, concomitant, or accidental. Thus, we performed Mendelian randomization (MR) analysis to evaluate the causal effects of several psychiatric disorders on IBS.

METHODS

Summary data of genome-wide association studies (GWASs) were obtained mainly from the Psychiatric Genomics Consortium (PGC) on individuals of European ancestry and from a recent GWAS on IBS. We used three MR methods, the inverse-variance weighting (IVW), weighted median (WM), and MR-Egger regression (MR-Egger). In addition, two other indicators, namely, the MR-IVW Cochran's Q statistic and MR-Egger intercept, were used to assess heterogeneity and detect directional horizontal pleiotropy, respectively.

RESULTS

Heritability was high for bipolar disorder (81.18 %, 95 % CI = 73.18-148.18 %), schizophrenia (33.88 %, 95 % CI = 33.57-38.19 %), and panic disorder (30.66 %, 95 % CI = 20.74-40.58 %). For other disorders, there was a low liability-scale SNP heritability for major depressive disorder (MDD) (0.67 %, 95 % CI = 0.61-0.73 %), anxiety disorder (7.63 %, 95 % CI = 1.67-13.59 %), PTSD (0.96 %, 95 % CI = 0.12-1.8 %), and IBS (2.44 %, 95 % CI = 2.13-2.75 %). We also observed that schizophrenia had a significant causal effect on IBS according to MR-IVW. Notably, the individual causal estimates of genetic instruments for MDD and schizophrenia were heterogeneous, but no pleiotropic effects were observed.

CONCLUSIONS

Our analyses revealed the causal effects of MDD and schizophrenia on IBS, a matter that has been subject to debate for decades, and also showed that IBS had causal effects on MDD.

Association Between Stress, Neuroinflammation, and Irritable Bowel Syndrome: The Positive Effects of Probiotic Therapy

Stress refers to an organism's response to environmental threats in normal condition to maintain homeostasis in the body. In addition, strong inflammatory reactions induced by the hypothalamic-pituitary-adrenal (HPA) axis under stress condition during a long time. Reciprocally, chronic stress can induce the irritable bowel syndrome (IBS) which is a well-known gut disorder thereby play an important role in the promotion and pathophysiology of neuropsychiatric diseases. It has been demonstrated that leaky gut is a hallmark of IBS, leads to the entrance the microbiota into the bloodstream and consequent low-grade systemic inflammation. In the current review, we will discuss the mechanisms by which stress can influence the risk and severity of IBS and its relationship with neuroinflammation. Also, the role of probiotics in IBS co-existing with chronic stress conditions is highlighted.

Gain of bipolar disorder-related lncRNA AP1AR-DT in mice induces depressive and anxiety-like behaviors by reducing Negr1-mediated excitatory synaptic transmission

BACKGROUND

Bipolar disorder is a complex polygenic disorder that is characterized by recurrent episodes of depression and mania, the heterogeneity of which is likely complicated by epigenetic modifications that remain to be elucidated.

METHODS

We performed transcriptomic analysis of peripheral blood RNA from monozygotic (MZ) twins discordant for bipolar disorder to identify disease-associated differentially expressed long noncoding RNAs (DE-lncRNAs), which were further validated in the PsychENCODE brain RNA-seq dataset. We then performed behavioral tests, electrophysiological assays, chromatin immunoprecipitation, and PCR to investigate the function of DE-lncRNAs in the mouse and cell models. Statistical analyses were performed using GraphPad Prism 9.0 or SPSS.

RESULTS

We identified a bipolar disorder-associated upregulated long non-coding RNA (lncRNA), AP1AR-DT. We observed that overexpression of AP1AR-DT in the mouse medial prefrontal cortex (mPFC) resulted in a reduction of both the total spine density and the spontaneous excitatory postsynaptic current (sEPSC) frequency of mPFC neurons as well as depressive and anxiety-like behaviors. A combination of the results of brain transcriptome analysis of AP1AR-DT overexpressing mice brains with the known genes associated with bipolar disorder revealed that NEGR1, which encodes neuronal growth regulator 1, is one of the AP1AR-DT targets and is reduced in vivo upon gain of AP1AR-DT in mice. We further demonstrated that overexpression of recombinant Negr1 in the mPFC neurons of AP1AR-DTOE mice ameliorates depressive and anxiety-like behaviors and normalizes the reduced excitatory synaptic transmission induced by the gain of AP1AR-DT. We finally identified that AP1AR-DT reduces NEGR1 expression by competing for the transcriptional activator NRF1 in the overlapping binding site of the NEGR1 promoter region.

CONCLUSIONS

The epigenetic and pathophysiological mechanism linking AP1AR-DT to the modulation of depressive and anxiety-like behaviors and excitatory synaptic function provides etiological implications for bipolar disorder.

Comorbid physical health outcomes in patients with bipolar disorder: An umbrella review of systematic reviews and meta-analyses

BACKGROUND

Although several meta-analyses have examined the association between bipolar disorder (BD) and its comorbid health outcomes, this evidence has not been comprehensively assembled.

OBJECTIVE

We aimed to systematically review existing meta-analyses based on multiple physical outcomes and validate the evidence level by examining the existing certainty of evidence.

METHODS

We systematically searched databases, including PubMed/MEDLINE, Embase, Google Scholar, and CINAHL, for articles published up to July 2023. We included meta-analyses of cohort, case-control, and/or cross-sectional studies investigating any comorbid health outcomes in patients with BD. We conducted quality assessments of the included meta-analysis using AMSTAR2. The credibility of findings was categorized into five levels of class and quality of evidence (CE), including convincing, highly suggestive, suggestive, weak, or not significant.

RESULTS

We analyzed 12 meta-analyses, including 145 original articles, covering 14 unique health outcomes with over 60 million participants across 29 countries and five continents. Among 14 health outcomes, BD was significantly associated with eight comorbid health outcomes, including dementia (equivalent odds ratio [eOR], 2.96 [95 % confidence intervals {CI}, 1.69-5.17]; CE=suggestive), Parkinson's disease (3.35 [1.72-6.53]; CE=suggestive), asthma (1.86 [1.42-2.42]; CE=weak), toxoplasmosis (1.69 [1.21-2.37]; CE=weak), hypertension (1.28 [1.02-1.60]; CE=convincing), breast cancer (1.33 [1.15-1.55]; CE=weak), obesity (1.64 [1.30-1.99]; CE=suggestive), and type 2 diabetes mellitus (1.98 [1.55-2.52]; CE=weak).

CONCLUSION

Individuals with BD are predisposed to numerous comorbid physical conditions, though these links are supported by various evidence levels and necessitate further studies. It is imperative that physicians be aware of these potential comorbidities in patients with BD and take proactive measures to manage them.

The Latest Data Concerning the Etiology and Pathogenesis of Irritable Bowel Syndrome

Globally, irritable bowel syndrome (IBS) is present in approximately 10% of the population. While this condition does not pose a risk of complications, it has a substantial impact on the patient's quality of life. Moreover, this disease has a significant financial impact on healthcare systems. This includes the direct costs associated with the diagnosis and treatment of these patients, as well as the indirect costs that arise from work absenteeism and reduced productivity. In light of these data, recent research has focused on elucidating the pathophysiological basis of this condition in order to improve the quality of life for affected individuals. Despite extensive research to date, we still do not fully understand the precise mechanisms underlying IBS. Numerous studies have demonstrated the involvement of the gut-brain axis, visceral hypersensitivity, gastrointestinal dysmotility, gut microbiota dysbiosis, food allergies and intolerances, low-grade mucosal inflammation, genetic factors, and psychosocial factors. The acquisition of new data is crucial for the advancement of optimal therapeutic approaches aimed at enhancing the general health of these patients while simultaneously reducing the financial burden associated with this ailment.

Consensus Statement on Managing Anxiety and Depression in Individuals with Inflammatory Bowel Disease

BACKGROUND

Studies have found a higher risk of comorbid anxiety and depression among patients with inflammatory bowel disease (IBD) compared with healthy individuals. If left untreated, comorbid depression and anxiety in patients with IBD can lead to poorer health outcomes and an increased healthcare utilization. The goal of this work was to develop a consensus statement to begin to address patient and provider needs and responsibilities related to screening and treatment of depression and anxiety symptoms among patients with IBD.

METHODS

A literature scan was conducted to gather evidence-based background information and recommendations on the screening, diagnosis, and treatment of anxiety and depression in patients with IBD. This was followed by the engagement of a panel of IBD and mental health experts and patient advocates using a modified Delphi process to synthesize the literature and distill the information into a core set of statements to support provider actions and care delivery.

RESULTS

Six statements were distilled from the literature and consensus process that link to the general management, screening, and treatment of anxiety and depression in patients with IBD.

CONCLUSIONS

Mental healthcare and support for IBD patients is critical; the statements included in this article represent practical considerations for IBD healthcare professionals in addressing key issues on provider awareness, knowledge and behaviors, screening and treatment resources, and patient education.

Patterns of Immune Dysregulation in Bipolar Disorder

Background

Bipolar disorder is a debilitating mood disorder associated with a high risk of suicide and characterized by immune dysregulation. In this study, we used a multi-faceted approach to better distinguish the pattern of dysregulation of immune profiles in individuals with BD.

Methods

We analyzed peripheral blood mononuclear cells (bipolar disorder N=39, control N=30), serum cytokines (bipolar disorder N=86, control N=58), whole blood RNA (bipolar disorder N=25, control N=25), and whole blood DNA (bipolar disorder N=104, control N=66) to identify immune-related differences in participants diagnosed with bipolar disorder compared to controls.

Results

Flow cytometry revealed a higher proportion of monocytes in participants with bipolar disorder together with a lower proportion of T helper cells. Additionally, the levels of 18 cytokines were significantly elevated, while two were reduced in participants with bipolar disorder. Most of the cytokines altered in individuals with bipolar disorder were proinflammatory. Forty-nine genes were differentially expressed in our bipolar disorder cohort and further analyses uncovered several immune-related pathways altered in these individuals. Genetic analysis indicated variants associated with inflammatory bowel disease also influences bipolar disorder risk.

Discussion

Our findings indicate a significant immune component to bipolar disorder pathophysiology and genetic overlap with inflammatory bowel disease. This comprehensive study supports existing literature, whilst also highlighting novel immune targets altered in individuals with bipolar disorder. Specifically, multiple lines of evidence indicate differences in the peripheral representation of monocytes and T cells are hallmarks of bipolar disorder.

Research Progress of Central and Peripheral Corticotropin-Releasing Hormone in Irritable Bowel Syndrome with Comorbid Dysthymic Disorders

Irritable bowel syndrome (IBS) is considered a stress disorder characterized by psychological and gastrointestinal dysfunction. IBS patients not only suffer from intestinal symptoms such as abdominal pain, diarrhea, or constipation but also, experience dysthymic disorders such as anxiety and depression. Studies have found that corticotropin-releasing hormone plays a key role in IBS with comorbid dysthymic disorders. Next, we will summarize the effects of corticotropin-releasing hormone from the central nervous system and periphery on IBS with comorbid dysthymic disorders and relevant treatments based on published literatures in recent years.

Genetic associations and potential mediators between psychiatric disorders and irritable bowel syndrome: a Mendelian randomization study with mediation analysis

Objective

Potential causal associations between psychiatric disorders and irritable bowel syndrome have been demonstrated in observational studies; however, these studies are susceptible to underlying confounding and reverse causation biases. We aimed to assess the causal effects of psychiatric disorders on irritable bowel syndrome (IBS) and the potential mediators from a genetic perspective by conducting a Mendelian randomization (MR) study with mediation analysis.

Method

Genetic instruments associated with psychiatric disorders, potential mediators, and IBS were obtained from large-scale genome-wide association studies (GWAS). Three MR methods - the inverse-variance weighted (IVW) method, MR-Egger method, and weighted median method, were used to investigate causal association estimates. Heterogeneity among different genetic instrumental variables (IVs) was assessed using Q tests. Additionally, the MR-PRESSO and MR-Pleiotropy methods were used to verify horizontal pleiotropy and detect outliers that might bias the results, which were removed from further analysis. Consequently, we used MR mediation analysis to investigate potential mediators in the causal associations between psychiatric disorders and IBS.

Results

MR provided evidence of the causal effects of genetically predicted broad depression, major depressive disorder (MDD), anxiety disorder, post-traumatic stress disorder (PTSD), and schizophrenia on IBS. The results of MR mediation analysis demonstrated that the reduction in acetate levels mediated 12.6% of the effects of broad depression on IBS; insomnia mediated 16.00%, 16.20%, and 27.14% of the effects of broad depression, MDD, and PTSD on IBS, respectively; and the increase in blood β-hydroxybutyrate levels mediated 50.76% of the effects of schizophrenia on IBS.

Conclusion

Our study confirmed the brain-gut axis involvement and potential modulators in the pathophysiology of psychiatric disorder-induced IBS from a genetic perspective, and suggests potential therapeutic targets for the disrupted brain-gut axis.

Psychiatric Comorbidities of Inflammatory Bowel Disease: It Is a Matter of Microglia's Gut Feeling

Inflammatory bowel disease (IBD), a common term for Crohn's disease and ulcerative colitis, is a chronic, relapse-remitting condition of the gastrointestinal tract that is increasing worldwide. Psychiatric comorbidities, including depression and anxiety, are more prevalent in IBD patients than in healthy individuals. Evidence suggests that varying levels of neuroinflammation might underlie these states in IBD patients. Within this context, microglia are the crucial non-neural cells in the brain responsible for innate immune responses following inflammatory insults. Alterations in microglia's functions, such as secretory profile, phagocytic activity, and synaptic pruning, might play significant roles in mediating psychiatric manifestations of IBD. In this review, we discuss the role played by microglia in IBD-associated comorbidities.

Association of major depressive disorder and increased risk of irritable bowel syndrome: A population-based cohort study and a two-sample Mendelian randomization study in the UK biobank

OBJECTIVE

To examine the association between depression and the risk of incident irritable bowel syndrome (IBS).

METHODS

We included 98,564 participants free of IBS in the UK biobank. Depression was defined by self-report and Hospital Episode Statistics. The main outcome was incident IBS. Cox proportional hazards regression models and two-sample mendelian randomization were performed to estimate the risk of incident IBS.

RESULTS

Among 98,564 participants, 8770 (8.9 %) participants had a depression diagnosis at baseline. During a median of 12.9-year follow-up, 224 cases of incident IBS were identified in patients with depression (2.0 per 1000 person-years), compared with 1625 cases in reference individuals (1.5 per 1000 person-years). After adjustment, the hazard ratio of incident IBS associated with depression was 1.26 (95 % CI: 1.01-1.41). Sensitivity analysis indicated similar results. The two-sample mendelian randomization based on the inverse variance weighted method provided evidence for the harmful role of depression in an increased risk of IBS with an OR of 1.57 (95 % CI: 1.24-1.99).

LIMITATIONS

Depression was mainly measured by self-report online CIDI-SF in the current study, rather than the gold diagnostic criteria including clinical structured interview, which might lead to potential measurement error. Lifestyle behaviors might change during the long-term follow-up, and time-varying covariates (i.e., smoking and alcohol status) may bias the estimate.

CONCLUSIONS

Depression is associated with an increased risk of incident IBS. Further studies are warranted to confirm the role of depression on incident IBS and elucidate the underlying mechanisms.

Depression and risk of gastrointestinal disorders: a comprehensive two-sample Mendelian randomization study of European ancestry

BACKGROUND

Major depressive disorder (MDD) is clinically documented to co-occur with multiple gastrointestinal disorders (GID), but the potential causal relationship between them remains unclear. We aimed to evaluate the potential causal relationship of MDD with 4 GID [gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS), peptic ulcer disease (PUD), and non-alcoholic fatty liver disease (NAFLD)] using a two-sample Mendelian randomization (MR) design.

METHODS

We obtained genome-wide association data for MDD from a meta-analysis (N = 480 359), and for GID from the UK Biobank (N ranges: 332 601-486 601) and FinnGen (N ranges: 187 028-218 792) among individuals of European ancestry. Our primary method was inverse-variance weighted (IVW) MR, with a series of sensitivity analyses to test the hypothesis of MR. Individual study estimates were pooled using fixed-effect meta-analysis.

RESULTS

Meta-analyses IVW MR found evidence that genetically predicted MDD may increase the risk of GERD, IBS, PUD and NAFLD. Additionally, reverse MR found evidence of genetically predicted GERD or IBS may increase the risk of MDD.

CONCLUSIONS

Genetically predicted MDD may increase the risk of GERD, IBS, PUD and NAFLD. Genetically predicted GERD or IBS may increase the risk of MDD. The findings may help elucidate the mechanisms underlying the co-morbidity of MDD and GID. Focusing on GID symptoms in patients with MDD and emotional problems in patients with GID is important for the clinical management.

Irritable bowel syndrome and mental health comorbidity - approach to multidisciplinary management

Irritable bowel syndrome (IBS) affects 5-10% of the global population. Up to one-third of people with IBS also experience anxiety or depression. Gastrointestinal and psychological symptoms both drive health-care use in people with IBS, but psychological comorbidity seems to be more important for long-term quality of life. An integrated care approach that addresses gastrointestinal symptoms with nutrition and brain-gut behaviour therapies is considered the gold standard. However, best practice for the treatment of individuals with IBS who have a comorbid psychological condition is unclear. Given the rising prevalence of mental health disorders, discussion of the challenges of implementing therapy for people with IBS and anxiety and depression is critical. In this Review, we draw upon our expertise in gastroenterology, nutrition science and psychology to highlight common challenges that arise when managing patients with IBS and co-occurring anxiety and depression, and provide recommendations for tailoring clinical assessment and treatment. We provide best practice recommendations, including dietary and behavioural interventions that could be applied by non-specialists and clinicians working outside an integrated care model.

Mental Illnesses in Inflammatory Bowel Diseases: mens sana in corpore sano

Background and aims: Inflammatory bowel diseases (IBD) are chronic disorders associated with a reduced quality of life, and patients often also suffer from psychiatric comorbidities. Overall, both mood and cognitive disorders are prevalent in chronic organic diseases, especially in the case of a strong immune component, such as rheumatoid arthritis, multiple sclerosis, and cancer. Divergent data regarding the true incidence and prevalence of mental disorders in patients with IBD are available. We aimed to review the current evidence on the topic and the burden of mental illness in IBD patients, the role of the brain-gut axis in their co-existence, and its implication in an integrated clinical management. Methods: PubMed was searched to identify relevant studies investigating the gut-brain interactions and the incidence and prevalence of psychiatric disorders, especially of depression, anxiety, and cognitive dysfunction in the IBD population. Results: Among IBD patients, there is a high prevalence of psychiatric comorbidities, especially of anxiety and depression. Approximately 20-30% of IBD patients are affected by mood disorders and/or present with anxiety symptoms. Furthermore, it has been observed that the prevalence of mental illnesses increases in patients with active intestinal disease. Psychiatric comorbidities continue to be under-diagnosed in IBD patients and remain an unresolved issue in the management of these patients. Conclusions: Psychiatric illnesses co-occurring in IBD patients deserve acknowledgment from IBD specialists. These comorbidities highly impact the management of IBD patients and should be studied as an adjunctive therapeutic target.

Causal relationship between bipolar disorder and inflammatory bowel disease: A bidirectional two-sample mendelian randomization study

Background: Growing evidence suggests a bidirectional association between bipolar disorder (BD) and inflammatory bowel disease (IBD); however, observational studies are prone to confounding, making causal inference and directional determination of these associations difficult.

Methods: We performed bidirectional two-sample Mendelian randomization (MR) and selected single nucleotide polymorphisms (SNPs) associated with BD and IBD as instrumental variables (IV). SNPs and genetic associations with BD and IBD were obtained from the latest genome-wide association studies (GWAS) in Europeans (BD: cases/controls: 20352/31358; IBD: 12882/21770; Crohn’s disease (CD): 5,956/14927; ulcerative colitis (UC): 6968/20464). The inverse-variance-weighted method was the major method used in MR analyses. MR-Egger, weight mode, simple mode, and weighted median were used for quality control.

Results: Genetically predicted BD (per log-odds ratio increase) was significantly positively associated with risk of IBD (OR: 1.18, 95% CI: 1.04–1.33), and UC (OR = 1.19, 95% CI: 1.05–1.35), but not CD (OR = 1.18, 95% CI: 0.95–1.48). The validation analysis found that combined OR of IBD, CD, and UC increased per log-OR of BD were 1.16(95% CI: 1.02–1.31), 1.20(95% CI: 0.98–1.48) 1.17(95% CI: 1.02–1.35), respectively. In contrast, no causal relationship was identified between genetically influenced IBD and BD.

Conclusion: Our results confirm a causal relationship between BD and IBD, which may influence clinical decisions on the management of BD patients with intestinal symptoms. Although the reverse MR results did not support a causal effect of IBD on BD, the effect of the IBD active period on BD remains to be further investigated.