Section - Quick Takes

05. Is Gut Microbiota Altered in Depression and Anxiety?

Published on September 1, 2025 Certification expiration date: September 1, 2028

Derick E. Vergne, M.D.

Assistant Professor - Tufts University School of Medicine

Key Points

Probiotic interventions show promise for mood disorders through microbiota gut-brain axis modulation. Pro-inflammatory bacteria increase while short-chain fatty-acid-producing bacteria decrease in both conditions.
Gut microbiota changes may involve specific bacterial taxa in each condition. Depression shows reduced Firmicutes with increased Actinobacteria and Proteobacteria, reflecting chronic stress physiology. Anxiety features increased Enterobacteriaceae abundance, potentially linked to acute stress responses.
Clinical translation remains premature due to small samples and methodological variability. Large metagenomic studies may yield new therapeutic targets for mood disorders.

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Gut Microbiota Variations in Depression and Anxiety

Today, I will be referencing a paper by Cao and colleagues published at BioMed Central Psychiatry on gut microbiota variations in depression and anxiety.

Depression affects about 5% of adults worldwide, while anxiety impacts around 4%. Interestingly, nearly 30% of those with depression also experience an anxiety disorder. These conditions contribute heavily to the global health burden.

The underlying mechanisms of these disorders include:

The monoamine hypothesis
The brain-derived neurotrophic factor cascade
Inflammatory responses

Notably, about 30% of patients with major depressive disorder do not respond to traditional monoamine antidepressants.

The Microbiota Gut-Brain Axis

Gastrointestinal symptoms often accompany these mental health issues, highlighting the role of the microbiota gut-brain axis. This axis suggests that gut microbiota interacts with the central nervous system, potentially influencing the development of depression and anxiety.

Probiotic interventions have shown promise in improving mood disorders through this axis. Abnormalities

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Table of Contents

Learning Objectives:

After completing this activity, the learner will be able to:

Evaluate the efficacy and safety profile of pramipexole as adjunctive therapy for treatment-resistant bipolar depression.
Assess the clinical application of semaglutide for managing clozapine-induced obesity.
Select appropriate antipsychotic medications for preventing hospitalization in patients with cannabis-induced psychosis.
Compare the relative efficacy of treatment options for treatment-resistant depression using network meta-analysis finding.
Recognize the emerging role of gut microbiota alterations in depression and anxiety disorders.

Original Release Date: September 1, 2025

Expiration Date: September 1, 2028

Experts: Paul Zarkowski, M.D., Kristin Raj, M.D., Oliver Freudenreich, M.D, David Gorelick, M.D. & Derick Vergne, M.D.

Medical Editors: Flavio Guzmán, M.D. & Sebastián Malleza M.D.

Relevant Financial Disclosures:
Oliver Freudenreich declares the following interests:
– Karuna: Research grant to institution, advisory board
– Vida: Consultant
– American Psychiatric Association: Consultant
– Medscape: Speaker
– Wolters-Kluwer: Royalties, editor
– National Council for Wellbeing: Consultant

All of the relevant financial relationships listed above have been mitigated by Medical Academy and the Psychopharmacology Institute.

None of the other faculty, planners, and reviewers for this educational activity have relevant financial relationships to disclose during the last 24 months with ineligible companies whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients.

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