Association of Depression With Incident Inflammatory Bowel Diseases: A Systematic Review and Meta-Analysis

Reply: MIND the Gap: Psychiatric Conditions in Inflammatory Bowel Disease

This commentary clarifies the methodological approaches of a recently published systematic review and meta-analysis on psychiatric conditions in IBD, addressing limitations in data, subgroup analysis, and publication bias. It emphasizes the need for further primary research to better understand the psychiatric burden in IBD patients and improve study design.

The gut-organ axis: Clinical aspects and immune mechanisms

The gut-brain axis exemplifies the bidirectional connection between the intestines and the brain, as evidenced by the impact of severe stress on gastrointestinal symptoms including abdominal pain and diarrhea, and conversely, the influence of abdominal discomfort on mood. Clinical observations support the notion of the gut-brain connection, including an increased prevalence of inflammatory bowel disease (IBD) in patients with depression and anxiety, as well as the association of changes in the gut microbiota with neurological disorders such as multiple sclerosis, Parkinson's disease, stroke and Alzheimer's disease. The gut and brain communicate via complex mechanisms involving inflammatory cytokines, immune cells, autonomic nerves, and gut microbiota, which contribute to the pathogenesis in certain gut and brain diseases. Two primary pathways mediate the bidirectional information exchange between the intestinal tract and the brain: signal transduction through bloodstream factors, such as bacterial metabolites and inflammatory cytokines, and neural pathways, such as neurotransmitters and inflammatory cytokines within the autonomic nervous system through the interaction between the nerve cells and beyond. In recent years, the basic mechanisms of the pathophysiology of the gut-brain axis have been gradually elucidated. Beyond the gut-brain interaction, emerging evidence suggests the influence of the gut extends to other organs, such as the liver and lungs, through intricate inter-organ communication pathways. An increasing number of reports on this clinical and basic cross-organ interactions underscore the potential for better understanding and novel therapeutic strategies targeting inter-organs networks. Further clarification of interactions between multiorgans premises transformative insights into cross-organ therapeutic strategies.

Review article: The role of the gut-brain axis in inflammatory bowel disease and its therapeutic implications

BACKGROUND

Treatments targeting the gut-brain axis (GBA) are effective at reducing symptom burden in irritable bowel syndrome (IBS). The prevalence of common mental disorders and IBS-type symptom reporting is significantly higher in inflammatory bowel disease (IBD) than would be expected, suggesting potential GBA effects in this setting. Manipulation of the GBA may offer novel treatment strategies in selected patients with IBD. We present a narrative review of the bi-directional effects of the GBA in IBD and explore the potential for GBA-targeted therapies in this setting.

METHODS

We searched MEDLINE, EMBASE, EMBASE Classic, PsychINFO, and the Cochrane Central Register of Controlled Trials for relevant articles published by March 2024.

RESULTS

The bi-directional relationship between psychological well-being and adverse longitudinal disease activity outcomes, and the high prevalence of IBS-type symptom reporting highlight the presence of GBA-mediated effects in IBD. Treatments targeting gut-brain interactions including brain-gut behavioural treatments, neuromodulators, and dietary interventions appear to be useful adjunctive treatments in a subset of patients.

CONCLUSIONS

Psychological morbidity is prevalent in patients with IBD. The relationship between longitudinal disease activity outcomes, IBS-type symptom reporting, and poor psychological health is mediated via the GBA. Proactive management of psychological health should be integrated into routine care. Further clinical trials of GBA-targeted therapies, conducted in selected groups of patients with co-existent common mental disorders, or those who report IBS-type symptoms, are required to inform effective integrated models of care in the future.

The Burden of Psychiatric Manifestations in Inflammatory Bowel Diseases: A Systematic Review With Meta-analysis

BACKGROUND

Psychiatric disorders in patients with inflammatory bowel disease (IBD) represent a significant but uncertain facet of the disease, with unsolved questions regarding their overall magnitude, their impact on intestinal disease, and the whole burden of psychiatric manifestations.

AIM

This systematic review summarizes the evidence on the prevalence and impact of psychiatric disorders, including depression, anxiety, bipolar disorder (BD), and schizophrenia, among patients with IBD.

METHODS

A systematic search across PubMed/MEDLINE, Embase, and Scopus databases from January 2010 to January 2023 was performed to identify relevant studies. The focus was on studies exploring the prevalence of specific psychiatric disorders in IBD patients compared to the general population and that reported specific outcome measures. A subsequent meta-analysis (MA) assessed the strength of the association between IBD and these psychiatric disorders, with data reliability ensured through rigorous extraction and quality assessment.

RESULTS

Out of 3,209 articles, 193 met the inclusion criteria and only 26 provided complete data for comprehensive analysis. These studies showed a significantly higher overall prevalence of psychiatric comorbidities in IBD patients compared to the general population. The MA showed a significant association between IBD and depression (pooled OR 1.42, 95% CI = 1.33-1.52, P < .0001) and anxiety (pooled OR 1.3, 95% CI = 1.22-1.44, P < .0001). The association between IBD and BD was significant (pooled OR 1.64, 95% CI = 1.20-2.24, P < .0001) but showed considerable heterogeneity (I2 = 94.01%). Only 3 studies examined the association between schizophrenia and IBD, providing widely heterogeneous results, with an inconclusive OR, estimated at 0.93 (95% CI = 0.62-1.39, P = .73).

CONCLUSIONS

This MA highlights the high prevalence of psychiatric disorders, particularly depression and anxiety, in IBD patients, which exceeds rates in the general population. BD in IBD is proving to be an important but under-researched area. The sparse and contradictory data on schizophrenia requires further investigation. These findings highlight the need for better understanding, early detection, and tailored mental health interventions in the management of IBD to significantly improve patients' quality of life.

An Anti-Inflammatory Diet and Its Potential Benefit for Individuals with Mental Disorders and Neurodegenerative Diseases-A Narrative Review

This narrative review synthesizes current evidence regarding anti-inflammatory dietary patterns and their potential benefits for individuals with mental disorders and neurodegenerative diseases. Chronic low-grade inflammation is increasingly recognized as a key factor in the etiology and progression of these conditions. The review examines the evidence for the anti-inflammatory and neuroprotective properties of dietary components and food groups, focusing on whole foods rather than specific nutrients or supplements. Key dietary components showing potential benefits include fruits and vegetables (especially berries and leafy greens), whole grains, legumes, fatty fish rich in omega-3, nuts (particularly walnuts), olive oil, and fermented foods. These foods are generally rich in antioxidants, dietary fiber, and bioactive compounds that may help modulate inflammation, support gut health, and promote neuroprotection. Conversely, ultra-processed foods, red meat, and sugary beverages may be harmful. Based on this evidence, we designed the Brain Anti-Inflammatory Nutrition (BrAIN) diet. The mechanisms of this diet include the modulation of the gut microbiota and the gut-brain axis, the regulation of inflammatory pathways, a reduction in oxidative stress, and the promotion of neuroplasticity. The BrAIN diet shows promise as an aid to manage mental and neurodegenerative disorders.

Implementation of 'IBD-Specific Cognitive Behavioural Therapy' for Patients with Inflammatory Bowel Diseases with Poor Mental Quality of Life, Anxiety and Depression

This paper describes the implementation of inflammatory bowel disease (IBD)-specific cognitive behavioural therapy (CBT) for IBD patients with poor quality of life (QoL), anxiety and depression, in four hospitals in the Netherlands. Treatment outcomes were compared with those of a previously published randomized control trial (RCT) of 'IBD-specific CBT', following a benchmark strategy. Primary outcome was IBD-specific QoL (IBDQ) completed before and after CBT, secondary outcomes were anxiety and depressive symptoms (HADS, CES-D). Semi-structured interviews were conducted among a pilot of gastroenterologists, nurse specialists and psychologists to evaluate 'IBD-specific CBT'. 94 patients started treatment (280 screened). At follow-up, 63 participants (67% compared to 81% in the RCT benchmark) completed the IBDQ. Treatment effect sizes of the implementation study were comparable and slightly larger than those of RCT benchmark. Gastroenterologists, IBD nurses and psychologists found CBT necessary for IBD patients with poor QoL, depression and/or anxiety disorders. 'IBD-specific CBT' can be successfully implemented. Regular supervision of psychologists performing 'IBD-specific CBT' treatment is needed.