Effects of Intravenous Ketamine on Explicit and Implicit Measures of Suicidality in Treatment-Resistant Depression
R. Price, M. Nock, D. Charney, S. Mathew
Biological Psychiatry July 9, 2009 DOI: 10.1016/j.biopsych.2009.04.029 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Interventional study (open-label, two-part) Peer reviewed |
|---|---|
| Sample size | 35 |
| Population | Patients with treatment-resistant depression assessed for suicidality |
| Intervention | Intravenous ketamine |
| Dose | subanesthetic dose (exact dose not stated) |
| Duration | 24 hours post-infusion for single dose; 12 days for repeated-dose study |
| Measures | MADRS-SI, Implicit Association Test (IAT) |
| Topics | Depression Esketamine Ketamine |
| Key points | A single ketamine infusion reduced MADRS-SI scores by 2.08 points on average at 24 hours, with 81% of patients scoring 0 or 1; repeated infusions sustained a 2.9-point reduction over 12 days. Implicit self-escape associations also decreased, correlating with explicit measures. |
Abstract
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 two concepts, may have utility in suicide assessment.
Methods: Twenty-six patients with treatment-resistant depression were assessed for suicidality 2 hours prior to, and 24 hours following, a single subanesthetic dose of intravenous ketamine using the suicidality item of the Montgomery-Asberg Depression Rating Scale (MADRS-SI). Ten patients also completed IATs assessing implicit suicidal associations at comparable time points. In a second study, 9 patients received thrice-weekly ketamine infusions over a 12-day period.
Results: 24-hours after a single infusion, MADRS-SI scores were reduced by an average of 2.08 points on a 0–6 scale (p<.001; d=1.37), and 81% of patients received a rating of 0 or 1 post-infusion. Implicit associations between self- and escape-related words 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 (2.9-point mean reduction; p<.001; d=2.42).
Conclusions: These preliminary findings support the premise that ketamine has rapid beneficial effects on suicidal cognition and warrants further study.