MDD Sample-Currently Depressed (n = 65): Patients (ages 18-55) will be selected with primary MDD currently depressed by DSM-IV criteria for recurrent MDD and current 17-item HDRS score greater than or equal to 18 or Montgomery-Asberg Depression Rating Scale (MADRS) (Noble et al 1991) greater than or equal to 20 indicating the moderately-to-severely depressed symptoms. All subjects must be physically healthy and aged 18 55 years.