Psychophysiological Effects of Lactobacillus Plantarum Ps128 in Patients with Major Depressive Disorder: a Pilot Study of 8-Week Open Trial

Background: Recent studies have suggested that gut-brain axis may be one of the mechanisms of major depression disorder. In animal studies, alteration of gut microbiota can affect animal’s depression or anxiety-like behavior, brain neurochemistry and inflammation. In human studies, the composition of gut microbiota is different between patients with MDD and healthy controls. In addition, supplementation of probiotics can improve mood status in community and clinical participants. Inflammation is one of possible pathway to connect gut and brain. Gut permeability and inflammation level are higher in patients with MDD. Lactobacillus plantarum PS128 in one of bacteria extracted from traditional fermented food, Fu-Tsai. It can alleviate depressive-like behavior reduce inflammation level in maternal separation mice. Until now, no clinical trial investigates the effect of probiotics in composition of gut microbiota and gut permeability.Aims: This pilot study is an 8-week open trial to investigate the effects of Lactobacillus plantarum PS128 on psychophysiology in patients with MDD. Method: This is a two-phase study. In the first phase, we will recruited patients fulfilling the following inclusion criteria: Age 20-65; fulfill Diagnostic and Statistical Manual of Mental Disorders fifth version (DSM-V) criteria of major depressive episode in recent 2 years; Psychotropics including antidepressants, antipsychotics and hypnotics have been kept unchanged for at least 1 months. The exclusion criteria are: comorbid with schizophrenia, bipolar disorder, or other substance use (except tobacco) disorder; having active suicidal or homicidal ideation; known allergy to probiotics; comorbid with hypertension, diabetes mellitus, irritable bowel syndrome, inflammatory bowl disease, liver cirrhosis, or autoimmune diseases; known active bacterial, fungal, or viral infections in one month; use of antibiotics, steroid, immunosuppressants, probiotics, or synbiotics in the month before collecting blood and fecal samples; pregnant or lactating women; who state to have dietary pattern changed or in diet within previous two months. Those with HAMD-17 >=14 in the first screen will be invited into the second phase intervention. In the second phase intervention, we will give eligible patients Lactobacillus plantarum PS128 for 8 weeks, and compare depression symptoms, gut microbiota, gut inflammation and permeability, and serum inflammation level before and after intervention.