This is an open-label (all people know the identity of the intervention), multi-center, prospective (a study in which the participants are identified and then followed forward in time for the outcome of the study), single-arm (all participants receiving one intervention) study. Approximately 260 participants will be enrolled in this study. This study consists of two phases: screening phase and treatment phase. In the treatment phase, participants will receive escitalopram for 8 weeks: escitalopram 10 mg per day for 1 week and then the dose of escitalopram will be flexibly adjusted up to maximum of 20 mg per day for the next 7 weeks, based on the investigator's clinical judgment. Safety evaluations will include assessment of adverse events, clinical laboratory tests, electrocardiogram, vital signs, and physical examination which will be monitored throughout the study. The total study duration will be approximately 2 years.