This study will address issues regarding both structural and functional brain changes that occur in mood disorders by including both imaging and cognitive tests on subjects at entry into the protocol, as well as re-testing with cognitive tests annually and study end-point. Magnetic resonance imaging will be used to obtain data on anatomic structures in the brain. MRI's will be repeated every two years. A small number of subjects (15) from each group of depressed patients (first episode, never treated and multiple past episode patients, never treated) as well as in healthy control subjects will along with the MRI be asked to complete a magnetic resonance spectroscopy (MRS) and a functional MRI.