Comparison of comorbid depression between irritable bowel syndrome and inflammatory bowel disease: A meta-analysis of comparative studies

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.

The microglial innate immune receptors TREM-1 and TREM-2 in the anterior cingulate cortex (ACC) drive visceral hypersensitivity and depressive-like behaviors following DSS-induced colitis

Inflammatory bowel disease (IBD) is a chronic condition with a high recurrence rate. To date, the clinical treatment of IBD mainly focuses on inflammation and gastrointestinal symptoms while ignoring the accompanying visceral pain, anxiety, depression, and other emotional symptoms. Evidence is accumulating that bi-directional communication between the gut and the brain is indispensable in the pathophysiology of IBD and its comorbidities. Increasing efforts have been focused on elucidating the central immune mechanisms in visceral hypersensitivity and depression following colitis. The triggering receptors expressed on myeloid cells-1/2 (TREM-1/2) are newly identified receptors that can be expressed on microglia. In particular, TREM-1 acts as an immune and inflammatory response amplifier, while TREM-2 may function as a molecule with a putative antagonist role to TREM-1. In the present study, using the dextran sulfate sodium (DSS)-induced colitis model, we found that peripheral inflammation induced microglial and glutamatergic neuronal activation in the anterior cingulate cortex (ACC). Microglial ablation mitigated visceral hypersensitivity in the inflammation phase rather than in the remission phase, subsequently preventing the emergence of depressive-like behaviors in the remission phase. Moreover, a further mechanistic study revealed that overexpression of TREM-1 and TREM-2 remarkably aggravated DSS-induced neuropathology. The improved outcome was achieved by modifying the balance of TREM-1 and TREM-2 via genetic and pharmacological means. Specifically, a deficiency of TREM-1 attenuated visceral hyperpathia in the inflammatory phase, and a TREM-2 deficiency improved depression-like symptoms in the remission phase. Taken together, our findings provide insights into mechanism-based therapy for inflammatory disorders and establish that microglial innate immune receptors TREM-1 and TREM-2 may represent a therapeutic target for the treatment of pain and psychological comorbidities associated with chronic inflammatory diseases by modulating neuroinflammatory responses.

New multimodal intervention to reduce irritable bowel syndrome (IBS) severity symptoms-Pilot study with a 12 month follow-up

INTRODUCTION

Irritable bowel syndrome (IBS) is characterized by patients' high level of suffering. Up to 60% of patients with IBS have symptoms of anxiety or depression and only little attention has been paid to their specific requirements. Anthroposophical multimodal therapy (AMT) has been shown to significantly improve health-related quality of life of patients with high symptomatic burden.

OBJECTIVE

The aim of this pilot study was to find out whether AMT meets the needs of IBS patients and the interactions of AMT with IBS, depression and anxiety.

METHODS

Patients with diagnosed IBS were included in a feasibility study and received 12 sessions of AMT over 8 weeks (drks.de, DRKS00016890). The primary endpoint was the change of the IBS severity score (IBS-SSS) and changes were calculated by linear mixed effects analyses. The secondary endpoints were changes of self-reported PHQ-9 and GAD-7 for mental comorbidity as well as self-valued effectiveness and satisfaction of AMT.

RESULTS

Thirty-six patients, 89% female, were included in the study. AMT was successfully applied to IBS patients (-45 points in the IBS-SSS, p < .05). AMT had a large positive effect (-84 points in IBS-SSS, p < .003) on patients without anxiety or depression. Over time, patients with higher anxiety scores worsened with regard to their IBS compared to patients with depression and without mental comorbidity. The AMT effect was maintained at a 12 month follow up and both mentally affected and unaffected patients, had even lower IBS severity than shortly after AMT. AMT modules were rated by IBS patients as very effective.

CONCLUSION

Our findings suggest that an 8-week program of AMT improves the severity of IBS with an ongoing effect at a 12 month follow-up. Especially for patients without psychological comorbidities, AMT is very successful. Future IBS therapies should incorporate a modified multimodal concept with stronger psychological therapy modules in parallel for patients with depression and anxiety.

Influence of Irritable Bowel Syndrome on Stress and Depressive Symptoms in Nurses: The Korea Nurses' Health Study

Despite the high risk of irritable bowel syndrome (IBS) and stress/depressive symptoms in nurses, limited research has examined the relationship between these conditions in female nurses. The purpose of this study was to determine the prevalence of IBS and the influence of IBS on stress and depressive symptoms in female nurses. We analyzed the data from the Korea Nurses’ Health Study. Among 7667 participants from the 7th survey conducted from December 2018 to September 2019, 178 nurses were identified as having IBS based on the Rome IV criteria. Using the propensity score matching, 712 were selected as a comparison group. Multivariate ordinal logistic regression analyses were conducted to examine the influence of IBS on stress and depressive symptoms. The prevalence of IBS was 2.3% and the prevalence of depressive symptoms among nurses with IBS was 13.5%. Female nurses with IBS were 2.214 times more likely to experience increased stress levels. However, when demographics, dietary habits, sleep quality, and depressive symptoms were considered, having IBS was no longer an influential factor for increased stress levels. When all the variables were considered, female nurses with IBS were still 2.205 times more likely to experience depressive symptoms. Adequate support is needed to relieve depressive symptoms in nurses with IBS.

Irritable Bowel Syndrome, Depression, and Neurodegeneration: A Bidirectional Communication from Gut to Brain

Patients with irritable bowel syndrome (IBS) are increasingly presenting with a wide range of neuropsychiatric symptoms, such as deterioration in gastroenteric physiology, including visceral hypersensitivity, altered intestinal membrane permeability, and gastrointestinal motor dysfunction. Functional imaging of IBS patients has revealed several abnormalities in various brain regions, such as significant activation of amygdala, thinning of insular and anterior cingulate cortex, and increase in hypothalamic gray matter, which results in poor psychiatric and cognitive outcomes. Interrelations between the enteric and central events in IBS-related gastrointestinal, neurological, and psychiatric pathologies have compelled researchers to study the gut-brain axis-a bidirectional communication that maintains the homeostasis of the gastrointestinal and central nervous system with gut microbiota as the protagonist. Thus, it can be disrupted by any alteration owing to the gut dysbiosis or loss of diversity in microbial composition. Available evidence indicates that the use of probiotics as a part of a balanced diet is effective in the management of IBS and IBS-associated neurodegenerative and psychiatric comorbidities. In this review, we delineate the pathogenesis and complications of IBS from gastrointestinal and neuropsychiatric standpoints while also discussing the neurodegenerative events in enteric and central nervous systems of IBS patients and the therapeutic potential of gut microbiota-based therapy established on clinical and preclinical data.

The Role of Epigenomic Regulatory Pathways in the Gut-Brain Axis and Visceral Hyperalgesia

The gut-brain axis (GBA) is broadly accepted to describe the bidirectional circuit that links the gastrointestinal tract with the central nervous system (CNS). Interest in the GBA has grown dramatically over past two decades along with advances in our understanding of the importance of the axis in the pathophysiology of numerous common clinical disorders including mood disorders, neurodegenerative disease, diabetes mellitus, non-alcohol fatty liver disease (NAFLD) and enhanced abdominal pain (visceral hyperalgesia). Paralleling the growing interest in the GBA, there have been seminal developments in our understanding of how environmental factors such as psychological stress and other extrinsic factors alter gene expression, primarily via epigenomic regulatory mechanisms. This process has been driven by advances in next-generation multi-omics methods and bioinformatics. Recent reviews address various components of GBA, but the role of epigenomic regulatory pathways in chronic stress-associated visceral hyperalgesia in relevant regions of the GBA including the amygdala, spinal cord, primary afferent (nociceptive) neurons, and the intestinal barrier has not been addressed. Rapidly developing evidence suggests that intestinal epithelial barrier dysfunction and microbial dysbiosis play a potentially significant role in chronic stress-associated visceral hyperalgesia in nociceptive neurons innervating the lower intestine via downregulation in intestinal epithelial cell tight junction protein expression and increase in paracellular permeability. These observations support an important role for the regulatory epigenome in the development of future diagnostics and therapeutic interventions in clinical disorders affecting the GBA.

The gut-brain axis in irritable bowel syndrome and inflammatory bowel disease

Research increasingly demonstrates the bidirectional communication between gut microbiota and the brain, enhancing the role of gut microbiota modulation in the treatment of central nervous system (CNS) disorders. The first five years of life are extremely important as it affects the development of gut microbiota, immune system and, consequently, the onset of psychometric alterations, particularly in genetically predisposed individuals. In this review, we focus on the link between specific microbial genera, gastrointestinal (GI) disorders, anxiety and depression and on the effects of different therapeutic strategies for mood disorders on gut microbiota.

Common mental disorders in irritable bowel syndrome: pathophysiology, management, and considerations for future randomised controlled trials

The frequent co-occurrence of irritable bowel syndrome and the common mental disorders of anxiety and depression is well established. A range of biological and psychosocial disease mechanisms are common to both disorders, many of which contribute to a dysregulated gut-brain axis. Clinical and subthreshold psychological comorbidity adds to the functional impairment and disease burden in individuals with irritable bowel syndrome. Progress is being made with regard to understanding irritable bowel syndrome in the clinical setting from a biopsychosocial perspective. However, until now, most trials of irritable bowel syndrome treatment still consider the disease as a gut disorder in isolation, which leaves major gaps in knowledge about disease-disease interactions and treatment outcomes in irritable bowel syndrome. In this Viewpoint, we review the epidemiology, pathophysiology, and management of anxiety and depression in individuals with irritable bowel syndrome. We also provide methodological recommendations for future randomised controlled trials and outline guidance for research that better incorporates psychiatric comorbidity into its design, with a view to improve treatment outcomes for individuals with irritable bowel syndrome.

Light-Mediated Inhibition of Colonic Smooth Muscle Constriction and Colonic Motility via Opsin 3

Opsin photoreceptors outside of the central nervous system have been shown to mediate smooth muscle photorelaxation in several organs. We hypothesized that opsin receptor activation in the colon would have a similar effect and influence colonic motility. We detected Opsin 3 (OPN3) protein expression in the colonic wall and demonstrated that OPN3 was present in enteric neurons in the muscularis propria of the murine colon. Precontracted murine colon segments demonstrated blue light (BL) -mediated relaxation ex vivo. This photorelaxation was wavelength specific and was increased with the administration of the chromophore 9-cis retinal and a G protein receptor kinase 2 (GRK2) inhibitor. Light-mediated relaxation of the colon was not inhibited by L-NAME or tetrodotoxin (TTX). Furthermore, BL exposure in the presence of 9-cis retinal decreased the frequency of colonic migrating motor complexes (CMMC) in spontaneously contracting mouse colons ex vivo. These results demonstrate for the first time a receptor-mediated photorelaxation of colonic smooth muscle and implicate opsins as possible new targets in the treatment of spasmodic gastrointestinal dysmotility.

Alexithymia and Inflammatory Bowel Disease: A Systematic Review

Background: Given the role of alexithymia—as the inability to identify, differentiate, and express emotions—in chronic and immune-mediated illness, this systematic review analyzed the prevalence of alexithymia in patients with inflammatory bowel diseases (IBDs), mainly represented by Crohn's disease (CD) and ulcerative colitis (UC).

Methods: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed throughout this systematic review of the literature published between 2015 and 2020 in indexed sources from PubMed, PsycINFO, Scopus, and Web of Science databases. Search terms for eligible studies were: “Inflammatory bowel disease” AND “Alexithymia” [Titles, Abstract, Keywords]. Inclusion criteria were: articles written and published in English from 2015 and up to April 2020, reporting relevant and empirical data on alexithymia and IBD.

Results: The initial search identified 34 indexed scientific publications. After screening, we found that five publications met the established scientific inclusion criteria. Overall, the mean value of alexithymia ranged from 39 to 53.2 [Toronto Alexithymia Scale (TAS-20) score], thus mostly falling in non-clinical range for alexithymia (≤51). Comparisons of alexithymia between patients with UC and CD highlighted that patients with CD showed externally oriented thinking and difficulties identifying feelings to a greater extent. Regarding comparisons with other samples or pathologies, patients with IBD were more alexithymic than healthy controls and less alexithymic than patients with major depressive disorder, but no difference was found when compared with patients with irritable bowel syndrome (IBS). Then, regarding correlations with other variables, alexithymia was positively associated with anxiety and depression, as well as with psychopathological symptoms and somatic complaints.

Conclusion: This systematic review suggests that patients with IBD cannot be generally considered alexithymic at a clinically relevant extent. However, their greater alexithymic levels and its associations with psychological variables and somatic distress may suggest a reactivity hypothesis, in which living with IBD may progressively lead to impaired emotion recognition over time. Specifically, the relationship between IBD and IBS should be further explored, paying deeper attention to the clinical psychological functioning of CD, as IBD requires more emotional challenges to patients.

Depression in the medically ill

BACKGROUND

Depressive disorders are significantly more common in the medically ill compared to the general population. Depression is associated with worsening of physical symptoms, greater healthcare utilization and poorer treatment adherence. The present paper provides a critical review on the assessment and management of depression in the medically ill.

METHODS

Relevant articles pertaining to depression in the medically ill were identified, reviewed and synthesized qualitatively. A systematic review was not performed due to the large breadth of this topic, making a meaningful summary of all published and unpublished studies not feasible. Notable studies were reviewed and synthesized by a diverse set of experts to provide a balanced summary.

RESULTS

Depression is frequently under-recognized in medical settings. Differential diagnoses include delirium, personality disorders and depressive disorders secondary to substances, medications or another medical condition. Depressive symptoms in the context of an adjustment disorder should be initially managed by supportive psychological approaches. Once a mild to moderate major depressive episode is identified, a stepped care approach should be implemented, starting with general psychoeducation, psychosocial interventions and ongoing monitoring. For moderate to severe symptoms, or mild symptoms that are not responding to low-intensity interventions, the use of antidepressants or higher intensity psychotherapeutic interventions should be considered. Psychotherapeutic interventions have demonstrated benefits with small to moderate effect sizes. Antidepressant medications have also demonstrated benefits with moderate effect sizes; however, special caution is needed in evaluating side effects, drug-drug interactions as well as dose adjustments due to impairment in hepatic metabolism and/or renal clearance. Novel interventions for the treatment of depression and other illness-related psychological symptoms (e.g. death anxiety, loss of dignity) are under investigation.

LIMITATIONS

Non-systematic review of the literature.

CONCLUSION

Replicated evidence has demonstrated a bidirectional interaction between depression and medical illness. Screening and stepped care using pharmacological and non-pharmacological interventions is merited.

Shift Work and Prostate Cancer: An Updated Systematic Review and Meta-Analysis

The International Agency of Research in Cancer (IARC) has recently confirmed shift work as a type 2A carcinogen. The results presented in published epidemiological studies regarding prostate cancer are inconsistent and the association remains controversial. The aims of this study were: (a) to investigate the possible association between shift work and prostate cancer incidence, identifying possible sources of heterogeneity; and (b) to analyze the potential effect of publication bias. A search for cohort and case-control studies published from January 1980 to November 2019 was conducted. The quality of the articles was assessed using the Newcastle-Ottawa Scale. Pooled OR were calculated using random-effects models. Heterogeneity was evaluated using Cochran's Q test and data were stratified by potential sources of heterogeneity. Publication bias was analyzed. Eighteen studies were included. No association was found between rotating/night-shift work and prostate cancer, pooled OR 1.07 (95%CI 0.99 to 1.15), I2 = 45.7%, p = 0.016. Heterogeneity was eliminated when only cohort studies (pooled OR 1.03; 95%CI 0.96 to 1.10; I2 = 18.9%, p = 0.264) or high-quality studies (pooled OR 0.99; 95%CI 0.89 to 1.08; I2 = 0.0%, p = 0.571) were considered. A publication bias was detected. An association between shift work and prostate cancer cannot be confirmed with the available current data. Future analytical studies assessing more objective homogeneous exposure variables still seem necessary.

Adjunctive minocycline for major mental disorders: A systematic review

OBJECTIVES

This meta-analysis of randomized controlled trials (RCTs) examined the efficacy and safety of minocycline for three major mental disorders: schizophrenia, bipolar disorder and major depressive disorder (MDD).

METHODS

A systematic literature search of major electronic databases was conducted. Meta-analysis of clinical efficacy as defined by the respective studies, all-cause discontinuation, adverse drug reactions (ADRs) with standardized mean difference (SMD) and risk ratios (RRs) and their 95% confidence intervals (CI) was conducted using random-effects model. Quality assessment was performed with the Jadad scale and Cochrane risk of bias.

RESULTS

Sixteen RCTs (n=1357) on minocycline (50-300 mg/day) for schizophrenia (13 RCTs, n=1196), bipolar depression (1 RCT, n=49), and MDD (2 RCTs, n=112) were analyzed separately by diagnosis. Twelve RCTs mentioned randomized allocation specifically; the weighted Jadad scores were 4.0. Adjunctive minocycline outperformed placebo in improving total psychopathology [SMD: -0.45 (95%CI: -0.73, -0.16), p=0.002; I²=77%], positive [SMD: -0.15 (95%CI: -0.28, -0.02), p=0.02; I²=0%], negative [SMD: -0.62 (95%CI: -0.95, -0.28), p=0.0003; I²=85%] and general psychopathology scores [SMD: -0.28 (95%CI: -0.53, -0.03), p=0.03; I²=59%] in schizophrenia. Minocycline showed no significant effect on depressive and manic symptoms in both bipolar depression and MDD. Minocycline caused significantly less headache (p=0.02, number-needed-to-harm=14, 95%CI=5-14) than placebo in schizophrenia. All-cause discontinuation and other ADRs were similar between minocycline and placebo in each diagnostic category.

CONCLUSION

In this meta-analysis, adjunctive minocycline appeared to be efficacious and safe for schizophrenia. However, the efficacy of adjunctive minocycline for bipolar depression or MDD could not be demonstrated.

REVIEW REGISTRATION

PROSPERO: CRD42018102483.

Effects of Serotonin and Slow-Release 5-Hydroxytryptophan on Gastrointestinal Motility in a Mouse Model of Depression

BACKGROUND & AIMS

Mood disorders and constipation are often comorbid, yet their shared etiologies have rarely been explored. The neurotransmitter serotonin (5-HT) regulates central nervous system and enteric nervous system (ENS) development and long-term functions, including gastrointestinal (GI) motility and mood. Therefore, defects in neuron production of 5-HT might result in brain and intestinal dysfunction. Tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme in 5-HT biosynthesis. A variant of TPH2 that encodes the R441H substitution (TPH2-R441H) was identified in individuals with severe depression. We studied mice with an analogous mutation (TPH2-R439H), which results in a 60%-80% decrease in levels of 5-HT in the central nervous system and behaviors associated with depression in humans. Feeding chow that contains 5-HTP slow release (5-HTP SR) to TPH2-R439H mice restores levels of 5-HT in the central nervous system and reduces depressive-like behaviors.

METHODS

We compared the effects of feeding chow, with or without 5-HTP SR, to mice with the TPH2-R439H mutation and without this mutation (control mice). Myenteric and submucosal plexuses were isolated from all 4 groups of mice, and immunocytochemistry was used to quantify total enteric neurons, serotonergic neurons, and 5-HT-dependent subsets of neurons. We performed calcium imaging experiments to evaluate responses of enteric neurons to tryptamine-evoked release of endogenous 5-HT. In live mice, we measured total GI transit, gastric emptying, small intestinal transit, and propulsive colorectal motility. To measure colonic migrating motor complexes (CMMCs), we isolated colons and constructed spatiotemporal maps along the proximodistal length to quantify the frequency, velocity, and length of CMMCs. We measured villus height, crypt perimeter, and relative densities of enterochromaffin and enteroendocrine cells in small intestinal tissue.

RESULTS

Levels of 5-HT were significantly lower in enteric neurons from TPH2-R439H mice than from control mice. TPH2-R439H mice had abnormalities in ENS development and ENS-mediated GI functions, including reduced motility and intestinal epithelial growth. Total GI transit and propulsive colorectal motility were slower in TPH2-R439H mice than controls, and CMMCs were slower and less frequent. Villus height and crypt perimeter were significantly decreased in colon tissues from TPH2-R439H mice compared with controls. Administration of 5-HTP SR to adult TPH2-R439H mice restored 5-HT to enteric neurons and reversed these abnormalities. Adult TPH2-R439H mice given oral 5-HTP SR had normalized numbers of enteric neurons, total GI transit, and colonic motility. Intestinal tissue from these mice had normal measures of CMMCs and enteric epithelial growth CONCLUSIONS: In studies of TPH2-R439H mice, we found evidence for reduced release of 5-HT from enteric neurons that results in defects in ENS development and GI motility. Our findings indicate that neuron production of 5-HT links constipation with mood dysfunction. Administration of 5-HTP SR to mice restored 5-HT to the ENS and normalized GI motility and growth of the enteric epithelium. 5-HTP SR might be used to treat patients with intestinal dysfunction associated with low levels of 5-HT.