A total of 25 depressed subjects between the ages of 21-75 who have current major depressive disorder without psychotic features by DSM-5 will be recruited. Subjects will be accepted into the protocol after an opportunity to review and provide voluntary written informed consent and completion of a comprehensive medical and psychiatric history, physical examination, mental status examination, and routine laboratory assessments. Patients will be recruited in outpatient settings to the Refractory Depression Clinic. Providers or Refractory Depression consult team will be informed if the patient may be eligible for participation in the ketamine protocol. Subjects must have established care in the VA Connecticut Healthcare System. If the Veteran is interested, a screening visit for further evaluation for the ketamine protocol will be scheduled. Veterans will receive up to 6 infusions for ketamine weekly, per PI discretion. The primary goal of this proposal is to test the effectiveness of repeated ketamine treatment (0.5 mg/kg; once or twice a week for up to 6 weeks; up to a total of 6 ketamine infusions). An open-label trial will be conducted that will include up to 25 Veterans with MDD with a follow-up of 6 months. This open-label trial will allow us to examine the safety and tolerability of the ketamine treatment in this population and the long-term effects. All patients will receive usual standard care during this trial.
