Treating Depression With Transcranial Direct Current Stimulation (tDCS)

Inclusion Criteria: * Has a diagnosis of a major depressive episode or bipolar disorder and is currently in a major depressive episode (without psychotic features) * Total pretreatment HDRS (Hamilton Depression Rating Scale)-24 score \>= 18 (The Hamilton Depression Rating Scale is an interviewer scored tool for assessing the severity of depressive symtoms. The scale ranges from 0 (no symptoms, absence of depression) to 64 Category Ham-24 Score Normal, not depressed 9 or less Mildly depressed 10 to 19 Moderately depressed 20 to 29 Markedly/severely depressed 30 or more) * Capable and willing to provide informed consent Exclusion Criteria: * History of depression previously untreated with medication, bipolar disorder, schizophrenia, schizoaffective disorder (non mood disorder), psychosis, depression secondary to a medical condition, mental retardation, substance dependence or abuse within the past year (except nicotine), psychotic features in this or previous episodes, amnestic disorder, dementia or mms\<24, DELIRIUM * Significant current history of autoimmune, endocrine, viral or vascular disorder affecting the brain * History of unstable cardiac disease, uncontrolled hypertension, or sleep apnea * Changes in psychotropic medications within two weeks prior to study entry or patient is unable to maintain stable doses throughout the study trial * Subject has an active suicidal plan and/or attempted suicide in the past twelve months * Patients with a CGI of 6 or greater * Subject is pregnant or has a positive pregnancy serum test