In this study, the investigators are going to examine the efficacy of escitalopram after dose escalation and evaluate remission rate. This study design is the double-blinded 6-week prospective study. It would be useful for clinicians because there were few study of high-dose antidepressant treatment in lack of remission in major depressive disorder patients. To control of bias, the investigators included patients with lack of remission after 4-week escitalopram treatment.
