Effect of Ketamine on Laboratory-induced Stress in Healthy Subjects

Stress exposure is one of the greatest risk factors for psychiatric illnesses like major depressive disorder (MDD) and post-traumatic stress disorder (PTSD). Stress resilience is the ability to experience stress without developing psychopathology. Enhancing stress resilience in at-risk populations could potentially protect against the development of stress-induced psychiatric disorders. Despite this, no resilience-enhancing pharmaceuticals have been identified yet. Pre-clinical studies showed that the administration of the glutamate N-methyl-D-aspartate (NMDA) receptor antagonist ketamine one week before an acute stress prevents the developing of depressive-like behavior in animals. In this project the study team proposes a pilot study to test if this stress prophylactic effect of ketamine applies also to humans. Ketamine will be compared to an active placebo control condition, the anesthetic midazolam, in a sample of healthy volunteers. The specific aims of this project are to test the effect of ketamine administered 1-week prior a laboratory-induced stress (1) on the positive and negative affect as measured with the Profile of Mood States (POMS) - Bipolar and (2) on the hypothalamic-pituitary-adrenal axis (HPA axis), adrenaline-noradrenaline axis (ANS axis), and self-reports of anxiety. The study team expects that subjects treated with ketamine, compared to midazolam, will experience reduced symptoms of negative affect and anxiety and a blunted hormonal response to an acute stress.

Inclusion criteria

• Males and females aged 18-45 years;
• Does not meet for any current or past psychiatric diagnoses as defined by DSM-V criteria;
• Participants must have a level of understanding of the English language sufficient to agree to all tests and examinations required by the study and must be able to participate fully in the informed consent process.

Exclusion criteria

• Any current or lifetime psychiatric disorder as determined by the Structured Clinical Interview for DSM-V Axis Disorders (SCID-5);
• Concomitant use of any medication with central nervous system activity, including treatment with antidepressants (classified as SSRIs, SNRIs, Atypical Antidepressants, TCAs);
• Any unstable medical illnesses including hepatic, renal impairment, gastroenterologic (including gastro-esophageal reflux disease), respiratory (including obstructive sleep apnea, or history of difficulty with airway management during previous anesthetics), cardiovascular (including ischemic heart disease and uncontrolled hypertension), endocrinologic, neurologic (including history of severe head injury), immunologic, or hematologic disease;
• Hypertension (systolic BP >160 mm Hg or diastolic BP >90 mm Hg) at screening or immediately prior to treatment with ketamine/midazolam;
• Clinically significant abnormal findings of laboratory parameters, physical examination, or ECG; clinically significant is defined by an abnormality that suggests a disease and/or organ toxicity that is new or has worsened from screening, or if the abnormality is of a degree that requires additional active management (e.g., further diagnostic investigation).
• Patients who have a positive urine toxicology test for illicit substances at screening and on the treatment day.
• Previous recreational use of PCP or ketamine.
• Subjects who have received ketamine in the past.