- Bipolar patients suffering from a major depressive episode currently or recently (in the month prior to scanning). Patients on psychiatric medication will have failed their current regimen for the treatment of their depression: they will meet criteria for depression, be seeking treatment for it, and have been on an adequate dose of antidepressant or mood stabilizer (as defined by the Antidepressant Treatment Form—see Oquendo et al., 2003) for 4 weeks or more.