- Patients must fulfill the criteria for recurrent MDD without psychotic features as defined by the DSM-IV, based on clinical assessment and confirmed by Structured Clinical Interview for DSM-IV Axis I Disorders - Clinical Version (SCID-I) plus the Major Depressive Disorder Specifiers included in the Research Version of the SCID-I. This includes at least one of the following diagnoses: 296.31, 296.32, and 296.33