Gut microbiota alterations linked to anxiety and depression in inflammatory bowel disease patients

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Frontiers in Medicine Published June 2, 2026 Medically reviewed June 2, 2026 DOI ↗ By Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

Key Takeaway

Consider that gut microbiota alterations are associated with anxiety and depression in IBD, but causality is unproven.

This is a systematic review of 1,040 patients with inflammatory bowel disease, examining associations between gut microbiota characteristics and symptoms of anxiety and depression. The authors synthesized evidence on gut microbiota characteristics, microbiota-targeted interventions such as probiotics and fecal microbiota transplantation, and psychological interventions. Key findings include reduced microbial alpha-diversity, enrichment of pro-inflammatory taxa, and depletion of short-chain fatty acid-producing bacteria associated with anxiety and depressive symptoms. Microbiota-targeted interventions modulated microbial composition and reduced anxiety and depression scores, while psychological interventions with microbiota profiling suggested potential effects on gut microbial composition. The authors note that findings remain heterogeneous, associations may not be fully explained by disease activity, and directionality and causal hypotheses are not clarified. Practice relevance suggests microbiota-targeted interventions and psychological therapies may represent promising strategies for managing psychological comorbidities in IBD, but future studies are warranted to test causal hypotheses.

Study Details

Study typeMeta analysis

EvidenceLevel 1

PublishedJun 2026

View Original Abstract ↓

BackgroundAnxiety and depression are highly prevalent among patients with inflammatory bowel disease (IBD) and are closely associated with reduced quality of life and poor treatment adherence. The gut–brain axis has been proposed as a key mechanistic framework, with the gut microbiota playing a central role. However, findings from clinical studies remain inconsistent, and a comprehensive synthesis of the evidence is lacking.ObjectiveThis systematic review aimed to integrate evidence from randomized controlled trials (RCTs) and prospective cohort studies to evaluate the associations between gut microbiota characteristics, microbiota-targeted interventions, and symptoms of anxiety and depression in patients with IBD.MethodsA systematic search was conducted in PubMed, Embase, the Cochrane Library, Web of Science, EBSCOhost, and Scopus. The search covered records from database inception to October 17, 2025. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A descriptive synthesis approach was used to summarize the findings. Study quality was assessed using the Critical Appraisal Skills Programme (CASP) checklist.ResultsTen studies were included, comprising six prospective cohort studies and four RCTs. These studies included a total of 1,040 patients with IBD. Cohort studies consistently showed that anxiety and depressive symptoms were associated with reduced microbial α-diversity, enrichment of pro-inflammatory taxa, and depletion of short-chain fatty acid (SCFA)-producing bacteria. These associations persisted after adjustment for inflammatory markers. They were also observed when analyses were restricted to patients in remission. This suggests that the associations may not be fully explained by disease activity. Evidence from RCTs showed that microbiota-targeted interventions, including probiotics and fecal microbiota transplantation, modulated microbial composition and reduced anxiety and depression scores. Studies combining psychological interventions with microbiota profiling also suggested potential effects on gut microbial composition. However, the findings remain heterogeneous.ConclusionCurrent evidence supports a close and potentially bidirectional association between gut microbiota dysbiosis and anxiety and depression in patients with IBD. Both microbiota-targeted interventions and psychological therapies may represent promising strategies for managing psychological comorbidities in IBD. Future large-scale, standardized longitudinal studies and randomized controlled trials are warranted to clarify directionality, test causal hypotheses, and develop personalized intervention approaches.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD420251166542.