Ketamine for Treatment Resistant Late-Life Depression

Primary Aim: To identify the best performing condition across a single intravenous infusion of ketamine (KET) 0.1 mg/kg, KET 0.25 mg/kg, KET 0.50 mg/kg) and midazolam (MID) 0.03 mg/kg on Montgomery-Asberg Depression Rating Scale (MADRS) treatment response (at least a 50% improvement in depression from baseline) 7 days after the infusion in up to 72 Veterans with Late-Life Treatment Resistant Depression (LL-TRD) , using a triple blind (patient, rater, anesthesiologist) Bayesian adaptive randomization design.

Hypothesis 1: Single KET 0.5 mg/kg infusion is superior to KET 0.1 mg/kg, KET 0.25 mg/kg, and MID 0.03 mg/kg measured by the proportion of participants demonstrating > 50% reduction on MADRS scores 7 days post-treatment.

Secondary Aim: To evaluate the durability of day 7 treatment response across 3 sub-anesthetic doses of a single KET (0.1 mg/kg, 0.25 mg/kg, and 0.50 mg/kg) and MID (0.03 mg/kg) infusion in veterans with LL-TRD during a 4 week follow-up.

Hypothesis 2: a single KET 0.5 mg/kg infusion will be superior to a single infusion of KET 0.1 mg/kg, KET 0.25 mg/kg, and MID 0.03 mg/kg as measured by the proportion of participants demonstrating > 50% reduction on MADRS scores at 28 days post-infusion.

Tertiary Aim: To evaluate the immediate and longer-term safety and tolerability of the most effective KET infusion relative to MID in vets with LL-TRD.

Hypothesis 3: KET infusion at the most effective dose will be safe and well tolerated compared to MID, as assessed by psychoactive and general side effect rating scales during and up to 4 weeks post study infusion.

Exploratory Aims:

• To measure the effects of the most effective dose of KET relative to MID on neurocognitive performance.
• To measure the effects the most effective dose of KET relative to MID on peripheral biomarkers of cellular plasticity and inflammation.
• To measure the effects the most effective dose of KET relative to MID on resting-state quantitative electroencephalography.

Inclusion criteria

• Male or female patients, 55 years of age,
• Participants must fulfill DSM 5 criteria for a Major Depressive Episode (Unipolar), based on a structured diagnostic interview, the DSM 5 M.I.N.I. 7.0
• Participants must have a history of at least one previous episode of depression prior to the current episode (recurrent MDD) or have chronic MDD (of at least two years' duration),
• Participants have not responded to two or more adequate trials of FDA-approved antidepressants, determined by Antidepressant Treatment Response Questionnaire (ATRQ) criteria.
• Participants must score 14 or greater on the Quick Inventory of Depressive Symptomatology-Self Report (QIDS-SR), and score 27 on the Montgomery Asberg Depression Rating Scale (MADRS),
• Each participant must have a level of understanding sufficient to agree to all tests and examinations required by the protocol and must sign an informed consent document.

Exclusion criteria

• Patients currently on fluoxetine,
• History of schizophrenia, schizoaffective disorder or any psychotic disorder, or bipolar disorder,
• Documented history of a psychotic disorder in a first-degree relative,
• Current diagnosis of obsessive-compulsive disorder (OCD) or eating disorder [bulimia nervosa or anorexia nervosa],
• Alcohol or substance use [except nicotine] within the preceding 6 months,
• Patients with any clinically significant personality disorder that would, in the investigator's judgment, preclude safe study participation,
• Patients judged to be at serious and imminent suicidal or homicidal risk,
• Serious, unstable medical illnesses including respiratory [obstructive sleep apnea, or history of difficulty with airway management during previous anesthetics], cardiovascular [including ischemic heart disease and uncontrolled hypertension], and neurologic [including history of severe head injury],
• For study entry, patients must be reasonable medical candidates for ketamine or midazolam infusion, as determined by a board-certified physician co-investigator during study Screening,
• Clinically significant abnormal findings of laboratory parameters [including urine toxicology screen for drugs of abuse], physical examination, or ECG,
• Hypertension (systolic BP >160 mm Hg or diastolic BP >90 mm Hg),
• Patients with one or more 11 seizures without a clear and resolved etiology,
• Patients starting hormonal treatment (e.g., estrogen) in the 3 months prior to Screening,
• Past intolerance or hypersensitivity to ketamine, or history of recreational use of phencyclidine (PCP) or ketamine,
• Past intolerance or hypersensitivity to midazolam,
• Age-related cognitive decline or mild dementia suggested by a score of < 25 on the Mini-Mental State Examination (MMSE) at Screening,
• Patients taking medications with known activity at the N-methyl-D-aspartate receptor (NMDA) or AMPA glutamate receptor [e.g., riluzole, amantadine, lamotrigine, memantine, topiramate, dextromethorphan, D-cycloserine], or the muopioid receptor,
• Patients taking any of the following medications: St John's Wort, theophylline, tramadol, metrizamide,
• Patients who demonstrate > 25% decrease in depressive symptoms as reflected by the QIDS-SR score from Screening to Randomization,
• Patients who have received electroconvulsive therapy (ECT) in the past 6 months prior to Screening,
• Patients currently receiving treatment with vagus nerve stimulation (VNS) or repetitive transcranial stimulation (rTMS).