Cognitive and subjective acute dose effects of intramuscular ketamine in healthy adults.
Michelle R Lofwall, Roland R. Griffiths, Miriam Z Mintzer
Experimental and Clinical Psychopharmacology November 1, 2006 DOI: 10.1037/1064-1297.14.4.439 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Placebo-controlled Double-blind Peer reviewed |
|---|---|
| Sample size | 18 |
| Population | Healthy adult volunteers |
| Intervention | Ketamine |
| Dose | 0.2 mg/kg, 0.4 mg/kg |
| Duration | 5 hours after drug administration |
| Topics | Esketamine Ketamine |
| Keywords | Ketamine study: ketamine Investigated Doses Drug influence Placebo-controlled design Volunteers Attention Motor skills Memory encoding Working memory speed Retrieval Accuracy Cognition Impaired Spared Selective No hallucinations Mystical experiences Subjective effects |
| Citations | 57 |
| Key findings | Ketamine selectively impairs memory encoding and working memory speed while sparing retrieval, attention, and accuracy. |
Abstract
Ketamine is a noncompetitive N-methyl-D-aspartate (NMDA) antagonist. Given the purported role of the NMDA receptor in long-term potentiation, the primary purpose of the present study was to further understand the dose-related effects of ketamine on memory. The study was also designed to provide information about the relative effects of ketamine on memory versus nonmemory effects and to more fully characterize ketamine's overall pattern and time course of effects. Single intramuscular injections of ketamine (0.2 mg/kg, 0.4 mg/kg) were administered to 18 healthy adult volunteers using a double-blind, placebo-controlled, crossover design. Word lists were used to evaluate episodic memory (free recall, recognition memory, source memory) and metamemory. Working memory, time estimation, psychomotor performance, and subjective effects were assessed repeatedly for 5 hours after drug administration. Ketamine selectively impaired encoding (as measured by free recall) while sparing retrieval, working memory while sparing attention, and digit symbol substitution task speed while sparing accuracy. Ketamine did not significantly impair recognition or source memory, metamemory, or time estimation. There were no hallucinations or increases in mystical experiences with ketamine. Memory measures were less sensitive to ketamine effects than subjective or psychomotor measures. Subjective effects lasted longer than memory and most psychomotor impairments. Ketamine produces selective, transient, dose- and time-related effects. In conjunction with previous studies of drugs with different mechanisms of actions, the observed selectivity of effects enhances the understanding of the pharmacological mechanisms underlying memory, attention, psychomotor performance, and subjective experience.
Comparable studies
Other randomized controlled trials on ketamine, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Subanesthetic Effects of the Noncompetitive NMDA Antagonist, Ketamine, in Humans Healthy human subjects recruited from the community | 1994 | Randomized controlled trial | n = 19 |
| Antidepressant Efficacy of Ketamine in Treatment-Resistant Major Depression: A Two-Site Randomized Controlled Trial Patients with treatment-resistant major depression experiencing a major depressive episode | 2013 | Randomized controlled trial | n = 73 |
| Remifentanil-induced Postoperative Hyperalgesia and Its Prevention with Small-dose Ketamine Patients undergoing major abdominal surgery | 2005 | Randomized controlled trial | n = 75 |
| Efficacy of Intravenous Ketamine for Treatment of Chronic Posttraumatic Stress Disorder Patients with chronic PTSD related to a range of trauma exposures | 2014 | Randomized controlled trial | n = 41 |
| Ketamine-Induced Deficits in Auditory and Visual Context-Dependent Processing in Healthy Volunteers Healthy volunteers | 2000 | Single-blind placebo-controlled study | n = 20 |
Citations in the library
Cited by 23
- Ketamine use: a review Addiction July 21, 2011
- Models of psychedelic drug action: modulation of cortical-subcortical circuits Brain October 22, 2021
- Therapeutic infusions of ketamine: Do the psychoactive effects matter? Drug and Alcohol Dependence January 15, 2014
- High doses of dextromethorphan, an NMDA antagonist, produce effects similar to classic hallucinogens. Psychopharmacology September 1, 2012
- A sub-set of psychoactive effects may be critical to the behavioral impact of ketamine on cocaine use disorder: Results from a randomized, controlled laboratory study. Neuropharmacology November 1, 2018
and 18 more in the library
Cites 14
- Subanesthetic Effects of the Noncompetitive NMDA Antagonist, Ketamine, in Humans Archives of General Psychiatry March 1, 1994
- Metacognition The MIT Press eBooks April 7, 1994
- Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance Psychopharmacology July 7, 2006
- Dose-Response Study of N,N-Dimethyltryptamine in Humans Archives of General Psychiatry February 1, 1994
- Attenuation of the Neuropsychiatric Effects of Ketamine With Lamotrigine Archives of General Psychiatry March 1, 2000
and 9 more in the library