COGNITIVE-FUNCTIONING AND GABA(A) BENZODIAZEPINE RECEPTOR-BINDING IN SCHIZOPHRENIA - A I-123 IOMAZENIL SPET STUDY/

Background: The role of the inhibitory neurotransmitter gamma aminobut yric acid (GABA) in schizophrenia has previously been investigated usi ng postmortem material, Recently, using single photon emission tomogra phy (SPET) with the selective benzodiazepine antagonist I-123-lomazeni l as the radioligand, we have demonstrated an in vivo relationship bet ween reduced GABA(A)/benzodiazepine receptor binding and the severity of positive symptomatology in schizophrenia. The present study aimed t o build on this using the same in vivo scanning techniques, and relati ng findings to cognitive functioning. Methods: Ten nonpsychiatric cont rol subjects and 15 schizophrenic patients, matched for age and handed ness, were scanned. A battery of neuropsychologic tests was also admin istered. Results: Correlational analysis revealed a pattern of increas ed correlations between GABA(A)/benzodiazepine receptor binding and ta sk performance, in the schizophrenic group compared to the control gro up. Conclusions: Findings are preliminary but suggest a relationship b etween reduced GABA(A)/benzodiazepine receptor binding and poorer cogn itive functioning, involving memory and visual attention processes, in the schizophrenic group but not in the control group. A role for GABA in the pathophysiology of schizophrenia is suggested, Limitations of the present study and suggestions for future research are discussed. ( C) 1998 Society of Biological Psychiatry.