Grant: Doctoral Research Award: Canada Graduate Scholarships

The gut-brain axis (GBA) is a bidirectional signalling pathway between our brain and our gastrointestinal tract. The GBA is currently being studied because of its potential relationship with our mood, anxiety, and related symptoms. Past research on the relationship between our gut microbiome and mental illness suggests that treatments like probiotics, microbe therapy, and fecal microbiota transplants (FMT), that work to repopulate our guts with healthy bacteria, show promising results in treating symptoms of anxiety and depression. This study uses an alternative gut repopulation treatment to FMT, known as Microbial Ecosystem Therapeutic (MET)-2, to relieve symptoms of depression. MET-2 is made up of 40 strains of bacteria from a single healthy donor and is taken orally in the form of a capsule. We will recruit 60 adults, across three sites, between 18-45 years of age with major depressive disorder (MDD) who will randomly be assigned to treatment or placebo groups. The primary goal of this study is to assess changes in mood in people with major depression before, during, and after taking MET-2 in comparison to a placebo pill. We also aim to look at changes in anxiety symptoms, inflammation and immune function through blood biomarker concentrations, and the level of repopulation of healthy gut bacteria as a response to treatment. Patients in the treatment group will receive MET-2 once a day for 6 weeks and patients in the placebo group will receive a matching placebo for 6 weeks. Patients' mood, anxiety, GI symptoms, sleep, and tolerability of treatment will be assessed biweekly. We predict that patients given MET-2 will experience greater improvement in depressive symptoms than those given the placebo because of the recolonization of the gut microbiome with healthy bacteria communicating with the brain through the GBA connection. This study is the first of its kind to evaluate the safety and efficacy of microbe therapy such as MET-2 compared to a placebo for MDD.