Ketamine for Depression and Suicide Risk

Inclusion Criteria: * Current psychiatric hospital inpatient at Mayo Clinic at time of initiation of treatment. * Ability to provide informed consent * Male/Female * Age 18-65 yrs. * Major Depressive Disorder or Bipolar Disorder I or Bipolar Disorder II with Patient Health Questionnaire-9 (PHQ 9) score ≥15 at hospital assessment * Treatment resistant depression (TRD) as defined by at least two previous antidepressant or mood stabilizing treatments for depression in adequate dose for 8 weeks * Patient reported overall suicide risk score ≥3 on the Suicide Status Form (SSF II-R) or score of ≥1on Item 9 of PHQ-9 (all at admission assessment) * Ability to pass comprehension assessment test related to effects of ketamine and trial objectives and criteria * Voluntary admission Exclusion Criteria: * Diagnosis of schizophrenia, schizoaffective disorder, or active psychosis * Index episode of depression greater than 2 years * Ongoing prescription of ≥4 mg lorazepam equivalents total daily or a.m. dosing of any benzodiazepine at time of assessment * Currently undergoing electroconvulsive therapy, deep brain stimulation or transcranial magnetic stimulation as acute series or for maintenance * Any active or unstable medical condition as judged by principal investigator * Previous use or abuse of methamphetamine, cocaine, stimulants (prescribed and illicit) within past 12 months * Any current abuse or dependence of alcohol or drugs (except nicotine) and abuse or dependence of drugs and alcohol only in full remission (\> 1 month, \< 12 months). Patients will be allowed to enroll if their drug and alcohol abuse / dependence is in full (complete, not partial) sustained (\> 1 year) remission. * History of traumatic brain injury * Developmental delay and intellectual disorder * Encephalopathy (clinical diagnosis within prior 12 months of delirium) * Cognitive disorder (mild and major) * Previous participation in earlier Ketamine trial * Pregnancy * Prisoners * Involuntarily hospitalized