Medications for the Treatment of Dysthymic Disorder and Double Depression

Inclusion Criteria: * Primary diagnosis of Dysthymic Disorder or Major Depressive Disorder with Antecedent Dysthymia * Women of childbearing potential must have negative pregnancy test at screen and agree to practice acceptable method of birth control * Score of at least 12 on the 24-item Hamilton Depression Scale at study entry * Initial screening labs grossly within normal limits * Signed written informed consent Exclusion Criteria: * Other Axis-I diagnoses such as delirium, dementia, and substance dependence (active in last year) or any substance abuse including alcohol within the past six months * Actively suicidal * CNS neoplasm, demyelinization disease, degenerative neurological disorder, active CNS infection, or any progressive CNS disorder that may confound interpretation of study results * History of seizure disorder, or EEG showing paroxysmal activity or head CT showing gross structural abnormality * Acute systemic medical disorder * Use of any psychotropic medications within 2 weeks prior to screen or 4 weeks prior to screen in the case of fluoxetine * Current use of any herbal medication such as St. John's wort, * Uncontrolled renal, hepatic, endocrine, cardiovascular, pulmonary, immunological, hematological or gastrointestinal disease * Any other abnormal medical screening tests judged by the investigator to be clinically significant * Received any experimental medication within 30 days prior to study entry * Patients presently in or soon to be starting psychotherapy * Prior treatment non-response to an adequate trial of citalopram, escitalopram, or sertraline * History of allergy to citalopram, escitalopram or sertraline