Effects of Intravenous Ketamine on Explicit and Implicit Measures of Suicidality in Treatment-Resistant Depression

Price, Rebecca B.; Nock, Matthew K.; Charney, Dennis S.; Mathew, Sanjay J.

doi:10.1016/j.biopsych.2009.04.029

« Previous Next »Biological Psychiatry
Volume 66, Issue 5 , Pages 522-526, 1 September 2009

Effects of Intravenous Ketamine on Explicit and Implicit Measures of Suicidality in Treatment-Resistant Depression

Rebecca B. Price
- Department of Psychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychology, Rutgers, the State University of New Jersey, Piscataway, New Jersey
- Address correspondence to Rebecca B. Price, M.S., Rutgers University, One Gustave L. Levy Place, Box 1230, New York, NY 10029
Matthew K. Nock
- Department of Psychology, Harvard University, Cambridge, Massachusetts
Dennis S. Charney
- Department of Psychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Neuroscience, Mount Sinai School of Medicine, New York, New York
- Department of Pharmacology & Systems Therapeutics, Mount Sinai School of Medicine, New York, New York
Sanjay J. Mathew
- Department of Psychiatry, Mount Sinai School of Medicine, New York, New York

Received 4 February 2009; received in revised form 14 April 2009; accepted 28 April 2009. published online 22 June 2009.

Background

Intravenous ketamine has shown rapid antidepressant effects in early trials, making it a potentially attractive candidate for depressed patients at imminent risk of suicide. The Implicit Association Test (IAT), a performance-based measure of association between concepts, may have utility in suicide assessment.

Methods

Twenty-six patients with treatment-resistant depression were assessed using the suicidality item of the Montgomery-Asberg Depression Rating Scale (MADRS-SI) 2 hours before and 24 hours following a single subanesthetic dose of intravenous ketamine. Ten patients also completed IATs assessing implicit suicidal associations at comparable time points. In a second study, nine patients received thrice-weekly ketamine infusions over a 12-day period.

Results

Twenty-four hours after a single infusion, MADRS-SI scores were reduced on average by 2.08 points on a 0 to 6 scale (p < .001; d = 1.37), and 81% of patients received a rating of 0 or 1 postinfusion. Implicit suicidal associations were also reduced following ketamine (p = .003; d = 1.36), with reductions correlated across implicit and explicit measures. MADRS-SI reductions were sustained for 12 days by repeated-dose ketamine (p < .001; d = 2.42).