This is a single-arm (clinical study in only one group of participants), open-label (all people know the identity of the intervention), multi-center (when more than one hospital or medical school team work on a medical research study), and prospective (study following participants forward in time) study. The study consists of 2 parts: Screening (that is, 5 days before study commences on Day 1) and Treatment (that is, Week 1-8). All the eligible participants will be receiving flexible doses of escitalopram orally in the dose range of 10 to 20 milligram per day (mg/day) for 8 weeks. Efficacy will primarily be evaluated by remission rate at the end of the study. Participants' safety will be monitored throughout the study.