Escitalopram Combination Comparison Study for Adult Patients With Major Depressive Disorder

Inclusion Criteria: * Patients must meet Diagnostic and Statistical Manual, Fourth Edition (DSM-IV) diagnostic criteria for Major Depressive Disorder * The patient's current depressive episode must be at least 12 weeks in duration. Exclusion Criteria: * Women who are pregnant, women who will be breastfeeding during the study, and women of childbearing potential who are not practicing a reliable method of birth control. * Patients who currently meet DSM-IV criteria for : a. bipolar disorder; b. schizophrenia or any psychotic disorder; c. obsessive-compulsive disorder; d. mental retardation or any pervasive developmental disorder or cognitive disorder. * Patients who are considered a suicide risk. * Patients with a history of seizure disorder, or any history of seizure, stroke, significant head injury, or any other condition that predisposes toward risk of seizure.