In this 6-week, double-blind, fixed-dose study, patients with major depressive disorder are randomly assigned to escitalopram (10 mg daily) plus PS128 (a psychobiotic) (300 mg two times daily, equivalent to 3 ×1010 CFU two times daily) or escitalopram (10 mg daily) groups. The rating scales and instrument, including Clinical Global Impression-Severity, 17-item Hamilton Rating Scale for Depression, Hamilton Anxiety Rating Scale, Global Assessment of Functioning, Heart Rate Variability, Depression and Somatic Symptoms Scale, Work and Social Adjustment Scale, Short form 36 and Pittsburgh Sleep Quality Index, are used to measure treatment outcomes at weeks 0, 1, 2, 3, 4, 5, and 6. UKU Side Effect Rating Scale and Gastrointestinal Symptom Rating Scale-Irritable Bowel Syndrome are used to measure side effects. Generalized estimating equations model will be used to analyze the differences between two groups with respect to efficacy and safety measures on time after adjusting for baseline severity, sex, age and age at onset of illness.
