This study is designed to determine if the antidepressant effects of deep anesthesia via propofol are related to EEG burst suppression.

Ten individuals with treatment resistant major depressive disorder will undergo 10 treatments of deep anesthesia via propofol over a 3-week period. Depression will be evaluated before and after treatment.

Inclusion Criteria:

• • Diagnosis of Major Depressive Disorder (MDD) or bipolar Disorder (I or II, most recent episode must be depression

  • Failed at least 2 anti-depressant treatments and no ECT in past 6 months
  • Age between 18-55 years
  • BMI < 35
  • Hamilton Rating Scale for Depression (HSRD) score > 18
  • Quick Inventory of Depression Scale (QIDS) score > 10.

Exclusion Criteria:

• • Diagnosis of primary psychotic disorder, dysthymia, or personality disorder

  • Significant pre-morbid cognitive impairment
  • Hypertension and current use of ACE inhibitor or AR blocker medications
  • Symptomatic coronary artery disease or congestive heart failure
  • History of transient ischemic or neurologic signs during the past year
  • History of or susceptibility to malignant hyperthermia
  • Contraindication to isoflurane or propofol anesthesia (as determined by anesthesiologist)
  • Diabetes requiring insulin
  • Poor kidney function
  • Chronic use of benzodiazepines or opioids
  • Individuals incompetent to provide consent (e.g. catatonic, psychotic).