The next step for eligible, consenting depressed subjects and healthy controls is a baseline hospital visit and baseline MRI. The baseline hospital visit will last about 4 hours. We will begin the baseline visit by collecting a urine sample for a drug (and, for women, pregnancy) test. As long as that is negative, we will then collect a blood sample of about 135cc. After the blood draw, participants will complete cognitive tests and meet again with the study psychiatrist. Participants will also complete a baseline Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) of their brain at the Veteran's Affairs (VA) Hospital in San Francisco.