SPECT [I-123]Iomazenil measurement of the benzodiazepine receptor in panicdisorder

Background: Alterations in benzodiazepine receptor function have long been hypothesized to play a role in anxiety. Animal models of anxiety involving exposure to chronic stress have shown a specific decrease in benzodiazepine receptor binding in frontal cortex and hippocampus, The purpose of this st udy was to examine benzodiazepine receptor binding patients with panic diso rder and comparison subjects. Methods: A quantitative measure related to benzodiazepine receptor binding (Distribution Volume (DV)) was obtained with single photon emission compute d tomography (SPECT) imaging of [I-123]iomazenil and measurement of radioli gand concentration in plasma in patients with panic disorder and healthy co ntrols. DV image data were analysed using statistical parametric mapping (s pm96). Results: A decrease in measures benzodiazepine receptor binding (DV) was fo und in left hippocampus and precuneus in panic disorder patients relative t o controls. Panic disorder patients who had a panic attack compared to pati ents who did not have a panic attack at the time of the scan had a decrease in benzodiazepine receptor binding in prefrontal cortex. Conclusions: Findings of a decrease in left hippocampal and precuneus benzo diazepine receptor binding may be related to alterations in benzodiazepine receptor binding, or other factors including changes in GABAergic transmiss ion or possible endogenous benzodiazepine compounds. Benzodiazepine recepto r function in prefrontal cortex appears to be involved in changes in state- related panic anxiety. (C) 2000 Society of Biological Psychiatry.