Fecal microbiota transplantation for treating major depressive disorder

A Clinical Trial to Evaluate the Safety and Efficacy of Fecal Microbiota Transplantation in a Population With Major Depressive Disorder

PHASE2; PHASE3 · University of Calgary · NCT04805879

This study is testing whether a new treatment using fecal microbiota transplantation can help adults with treatment-resistant depression feel better while they continue their usual antidepressant medication.

Quick facts

PhasePHASE2; PHASE3
Study typeInterventional
Enrollment80 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorUniversity of Calgary (other)
Locations1 site (Calgary, Alberta)
Trial IDNCT04805879 on ClinicalTrials.gov

What this trial studies

This clinical trial aims to evaluate the safety and efficacy of fecal microbiota transplantation (FMT) in adults suffering from treatment-resistant depression (TRD). It is a phase 2/3, double-blinded, randomized controlled trial involving 80 participants who will receive either FMT capsules or placebo capsules while continuing their current antidepressant treatment. Participants will be monitored for 14 weeks post-treatment to assess improvements in depression symptoms and changes in their intestinal microbiome. The study seeks to determine if FMT can lead to sustainable mental health benefits for individuals with TRD.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18-65 with a primary diagnosis of major depressive disorder and a history of inadequate response to at least two approved antidepressants.

Not a fit: Patients with substance use disorders or other specified mental health conditions may not benefit from this study.

Why it matters

Potential benefit: If successful, this approach could provide a novel treatment option for patients with treatment-resistant depression.

How similar studies have performed: While the concept of using FMT for mental health is novel, preliminary studies have shown promising results in related areas, indicating potential for success.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Between 18-65 years of age:

   Participants should be at least 18 years old and not older than 65 years at the day of screening
2. Have a primary diagnosis of MDD according to the M.I.N.I. International Neuropsychiatric Interview (MINI)47
3. Medical history suggestive of Treatment Resistant Depression (TRD). (inadequate response to at least 2 approved antidepressants. at least one of which is in the current episode of depression)48
4. Have been on a current treatment with a approved antidepressant at an adequate dose for at least 8 weeks
5. A MADRS score of ≥ 19 at screening and visit 2

Additional Inclusion Criteria:

- Participants who will be included in the IBS-D cohort should have a confirmed diagnosis of IBS-D as indicated by the referring gastroenterologist.

Exclusion Criteria:

* 1. Participant meets Diagnostic and Statistical Manual of Mental Disorders (DSM-5)1 Criteria for the following conditions according to the M.I.N.I: f) Substance Use Disorder within the last 3 months. \*(Criteria should include Alcohol and non-alcohol substances except Cannabis) g) Moderate or severe Substance use disorder for Cannabis use the last 3 months h) Active Anorexia Nervosa or Bulimia nervosa i) Schizophrenia or schizoaffective disorder j) Active suicidality 2. Regular intake of non-steroidal anti-inflammatory drugs, antibiotics, or iron supplements for medical purposes in the 3 months prior to study entry 3. Use of prebiotics or probiotics for medical purposes for more than 2 weeks within the last 3 months 4. Clinically diagnosed chronic gastrointestinal diseases (IBD, Crohn's disease, Ulcerative colitis, Celiac disease) 5. Conditions causing immune suppression 6. Not breastfeeding, pregnant or seeking to get pregnant during the course of this study. Be using an acceptable method of birth control (implants, injectable, combined oral contraceptives, IUDs, sexual abstinence or a vasectomized partner) 7. Reported allergy to Vancomycin or Nitazoxanide

Where this trial is running

Calgary, Alberta

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Depression, Treatment Resistant Depression, FMT, Fecal Microbiota Transplantation, Microbiome, gut brain axis, Major depression

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.