Open Treatment of Minocycline in Geriatric Depression

Inclusion Criteria: 1. Age: Participants must be 55 years old or older (female patients must be postmenopausal); 2. Diagnosis: Major depression, either unipolar or bipolar without psychotic features (by Diagnostic and Statistical Manual of Mental Disorders (DSM) IV criteria and assessed on the Structured Clinical Interview for the Diagnostic and Statistical Manual for Mental Disorders (SCID); 3. Severity of depression: 17-item Hamilton Depression Rating Scale(HRSD)\>14; 4. Failure to achieve substantial improvement of depressive symptoms (entry HDRS\>14) after at least 6 weeks of treatment with a mood stabilizer or an antidepressant (SSRI, SNRI, or TCA) reaching therapeutic dosages (daily dose of at least: fluoxetine 20 mg, sertraline 150 mg, paroxetine 20 mg, citalopram 20 mg, escitalopram 10 mg, venlafaxine 150 mg, duloxetine 60 mg). 5. Fluency in English 6. Capacity to provide informed consent. Exclusion Criteria: 1. High suicide risk, i.e. intent or plan to attempt suicide in near future; 2. Presence of any current Axis I psychiatric disorder (other than unipolar or bipolar major depression or generalized anxiety disorder) including substance abuse (those with a history of substance abuse must be abstinent for at least 3 months prior to entry); 3. Axis II diagnosis of antisocial personality disorder, schizotypal or severe borderline personality, mental retardation and pervasive developmental disorder (DSM-IV); 4. Dementia of more than mild severity (MMSE \< 20); 5. History of psychiatric disorders such as psychotic depression, primary psychotic disorder 6. Acute or severe medical illness, i.e., delirium, metastatic cancer, decompensated cardiac, liver or kidney failure, major surgery, stroke or myocardial infarction during the three months prior to entry, advanced autoimmune deficiency, or "end stage" chronic obstructive pulmonary disease; or drugs known to cause depression, e.g., reserpine, alpha-methyl-dopa, steroids, sympathomimetics withdrawal; 7. Presence of a significant neurological disease such as Parkinson's disease, primary or secondary seizure disorders, intracranial tumors, severe head trauma; neurodegenerative diseases i.e. Multiple Sclerosis; 8. History of intolerance to minocycline or other tetracyclines; use of concomitant drugs that may provide reason to believe that minocycline is contraindicated; 9. Patients on anticoagulants (except low-dose aspirin); patients on ergot alkaloids 10. Patients on MAOIs; 11. Patients' unwillingness or inability to gradually withdraw all other psychotropic medications (except for the following: Antidepressants, mood stabilizers, and low and stable doses of opiates and non-benzodiazepine hypnotics, e.g. zolpidem (5 or 10 mg), zaleplon (5 or 10 mg). 12. Inability to perform any of the ADLs (MAI: ADL subscale) even with assistance, e.g. walking with a cane is not an exclusion criterion; 13. Inability to speak English; 14. Corrected visual acuity \< 20/70;