ABSENCE OF KETAMINE EFFECTS ON MEMORY AND OTHER COGNITIVE FUNCTIONS IN SCHIZOPHRENIC-PATIENTS

Glutamatergic dysfunction may play an important role in both the patho physiology of schizophrenia, and impaired memory commonly observed in that disorder. NMDA receptor antagonists impair learning/memory in ani mal models, putatively based on its ability to block longterm potentia tion (LTP) in the hippocampus. Although well studied in animal models, research in humans is limited and confounded by administration of NMD A antagonists before the learning experience. Based on presumed glutam atergic dysfunction, it was predicted that the NMDA antagonist ketamin e would not effect memory in schizophrenic subjects. Bolus injections of ketamine (0.5 mg/kg) or placebo were given to seven patients with s chizophrenia in this double-blind cross-over study. Immediately prior to injection, subjects were administered verbal and figural memory tes ts. Delayed recalls were obtained 30-45 min postinjection. In order to rule out drug-induced generalized cognitive impairments, other cognit ive tasks were administered pre- and postinjection. The results indica te no differences between the drug and placebo conditions for either m emory task, and no changes on the other cognitive tasks observed. Copy right (C) 1996 Elsevier Science Ltd.