Assessment of the Efficacy and Safety of Fecal Microbiota Transplantation (FMT) in Patients With Major Depressive Disorder

This multicenter, randomized, double-blind, placebo-controlled study aims to compare the efficacy and safety of adjunctive FMT in patients with major depressive disorder (MDD) who show limited response to initial drug therapy. A total of 600 patients experiencing depressive episodes will be screened, with all receiving escitalopram oxalate for an initial 2-week period. Of these, 214 participants who exhibit suboptimal therapeutic response to early antidepressant treatment will be enrolled and randomized in a 1:1 ratio to either the experimental group or control group. During the intervention, participants will continue their existing antidepressant regimen and receive a 4-week treatment with either microbiota capsules or placebo. An additional 20-week follow-up assessment will then be conducted to evaluate outcomes.