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Absence of ketamine effects on memory and other cognitive functions in schizophrenia patients.

D J LaPorte, Adrienne C. Lahti, B Koffel, Carol A. Tamminga

Journal of Psychiatric Research September 1, 1996 DOI: 10.1016/0022-3956(96)00018-0 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Double-blind cross-over study Peer reviewed
Sample size 7
Population Patients with schizophrenia
Intervention Ketamine
Dose 0.5 mg/kg
Topics Ketamine Esketamine
Keywords Humans Cross-over studies Double-blind method Cognition Memory Schizophrenia Adult Female
Key points Ketamine (0.5 mg/kg) produced no differences from placebo on verbal or figural memory tasks in seven patients with schizophrenia, and no changes on other cognitive tasks. The authors had predicted this null result based on presumed glutamatergic dysfunction in schizophrenia.

Abstract

Glutamatergic dysfunction may play an important role in both the pathophysiology of schizophrenia, and impaired memory commonly observed in that disorder. NMDA receptor antagonists impair learning/memory in animal models, putatively based on its ability to block long-term potentiation (LTP) in the hippocampus. Although well studied in animal models, research in humans is limited and confounded by administration of NMDA antagonists before the learning experience. Based on presumed glutamatergic dysfunction, it was predicted that the NMDA antagonist ketamine would not effect memory in schizophrenic subjects. Bolus injections of ketamine (0.5 mg/kg) or placebo were given to seven patients with schizophrenia in this double-blind cross-over study. Immediately prior to injection, subjects were administered verbal and figural memory tests. Delayed recalls were obtained 30-45 min postinjection. In order to rule out drug-induced generalized cognitive impairments, other cognitive tasks were administered pre- and postinjection. The results indicate no differences between the drug and placebo conditions for either memory task, and no changes on the other cognitive tasks observed.

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

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Ketamine Esketamine