Effectiveness Study of Vilazodone to Treat Depression and to Discover Genetic Markers Associated With Response

Inclusion Criteria:

• Male or female patients 18-65 years of age, inclusive.
• A diagnosis of MDD, single episode or recurrent, according to DSM-IV-TR (296.2/296.3) with a current Major Depressive Episode of less than two year's duration with a minimum duration of at least 4 weeks.
• HAM-D score ≥ 22.
• HAM-D item 1 (depressed mood) score ≥ 2.
• Patients must be able to provide written informed consent to participate before beginning any trial related activities.
• Patients must be able to speak, read and understand English and possess the ability to respond to questions and follow simple instructions.

Exclusion Criteria:

• A current (or within 6 months prior to the Screening Visit) Axis I disorder of Post Traumatic Stress Disorder, Eating Disorder, Obsessive Compulsive Disorder (Generalized Anxiety Disorder, Social Phobia or Simple Phobia will be allowed).
• A history of schizophrenia, schizoaffective disorder or bipolar I or II disorder (with a history of hypomanic or manic episodes).
• DSM-IV-TR criteria for substance abuse (alcohol or drugs) within 3 months prior to Screening Visit or substance dependence within 6 months prior to the Screening Visit.
• Criteria for any of the following DSM-IV-TR MDD Specifiers: [a] With Catatonic Features; [b] With Postpartum Onset; [c] With Seasonal Pattern.