PB-18 Probiotic for Mild to Moderate Depression

Starting soon · Not applicable · Has a placebo group

Conditions studied: Depressive Disorder

In brief

The goal of this clinical trial is to learn if Bifidobacterium PB-18 can treat mild to moderate depressive disorder in adults aged 18 to 65 years who are not taking antidepressants or other psychotropic medications during the study. It will also learn about the safety of Bifidobacterium PB-18 and explore its potential effects on the gut-brain axis. The main questions it aims to answer are: Does Bifidobacterium PB-18 increase the response rate at Week 8, defined as a reduction of at least 50% from baseline in the 17-item Hamilton Depression Rating Scale (HAMD-17)? What adverse events occur in participants receiving Bifidobacterium PB-18? How do gut microbiota, metabolite profiles, and related biological markers change after treatment with Bifidobacterium PB-18? Researchers will compare Bifidobacterium PB-18 with a placebo, a look-alike powder that does not contain PB-18, to see if Bifidobacterium PB-18 improves depressive symptoms. Participants will: Be randomly assigned to receive Bifidobacterium PB-18 or placebo in a 1:1 ratio Take the assigned study product once daily for 8 weeks Visit the study site at baseline, Week 4, and Week 8 for symptom and safety assessments Complete study questionnaires, including HAMD-17, HAMA, PSQI, and CBCT Provide blood and stool samples at baseline and Week 8 for exploratory biological analyses

Key facts

Study ID: NCT07562516
Run by: First Affiliated Hospital of Zhejiang University
People needed: 88
Starts: 2026-05-05
Expected to finish: 2027-04-30
Last updated by the study team: 2026-05-07

Who can join

Age: 18 and older, up to 65. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

Outpatient or inpatient participants, aged 18 to 65 years (inclusive), of any sex
Current episode meets Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria for depressive disorder
Baseline score on the 17-Item Hamilton Depression Rating Scale is 7 to 24, inclusive
No concomitant use of antidepressants or other psychotropic medications during the study
Elementary school education or above, able to understand the study requirements and complete the rating scales
Participant personally signs the informed consent form and is willing to complete follow-up according to the study protocol

You may not qualify if…

Current or past diagnosis, according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria, of bipolar disorder, schizophrenia spectrum and other psychotic disorders, neurocognitive disorders, neurodevelopmental disorders, or substance-related and addictive disorders
Presence of significant psychotic symptoms, such as delusions or hallucinations
Severe or unstable diseases of the central nervous system, cardiovascular system, respiratory system, liver, kidneys, endocrine system, hematologic system, or other systems that, in the investigator's judgment, make the participant unsuitable for the study
Evident suicide risk, defined as a score of 1 or higher on the suicide item of the 17-Item Hamilton Depression Rating Scale
Active inflammatory disease
Gastrointestinal infection, tumor, or other organic digestive disease, including but not limited to irritable bowel syndrome, Crohn disease, ulcerative colitis, or celiac disease
History of major gastrointestinal surgery
Use of antibiotics, probiotics, prebiotics, or related functional products within 1 month before study entry
Allergy to the study product or any of its components
Pregnant or breastfeeding women
Unable or unwilling to take the study product as required by the protocol
Any other condition that, in the investigator's judgment, makes the participant unsuitable for the study

Full record on ClinicalTrials.gov

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