Minocycline for Bipolar Depression

Inclusion Criteria: * Meets DSM-IV criteria for Bipolar I Disorder or Bipolar II disorder, depressed phase * A baseline score of at least 18 on the Montgomery-Asberg Depression Rating Scale (MADRS) * Participants on mood stabilizer medication for at least two weeks prior to starting the study, and must remain on the treatment during the study * Able to understand English Exclusion Criteria: * DSM-IV diagnosis of Bipolar NOS, Cyclothymia, or Schizoaffective Bipolar type * Pregnant women or women of child bearing potential who are not using a medically accepted means of contraception (defined as oral contraceptive pill or implant, condom, diaphragm, spermicide, IUD, s/p tubal ligation, partner with vasectomy) * Serious suicide or homicide risk * Unstable medical illness including cardiovascular, hepatic, renal, respiratory, endocrine, neurological, or hematological disease * Clinical or laboratory evidence of hypothyroidism; if maintained on thyroid medication must be euthyroid for at least 1 month before visit 1 * Drug/alcohol dependence within past 30 days, or current substance use disorder that requires detoxification * Current use of minocycline or history of anaphylactic reaction or intolerance to minocycline * Primary clinical diagnosis of antisocial or borderline personality disorder * Patients with metallic foreign bodies or claustrophobia will be excluded from the MRS component