Increased benzodiazepine receptor density in the prefrontal cortex in patients with panic disorder

There are published studies concerning a regionally changed function of GAB A-benzodiazepine-receptor-complexes in anxiety disorder. These studies impl icate the limbic lobe, the brainstem and the prefrontal cortex. Using I-123 -Iomazenil and single photon emission tomography (SPET) we investigated the benzodiazepine receptor density in twelve patients with panic disorder who had never been treated with benzodiazepines before. Nine age- and sex-matc hed volunteers who were free of mental illness served as controls. Patients with panic disorder showed a significant increase of benzodiazepine recept or binding in the right supraorbital cortex and a trend to an increased upt ake in the right temporal cortex. There was no correlation between receptor density and scores on Spielberger's State Trait Anxiety Inventory in the p atient group. Since the findings cannot be explained by benzodiazepine expo sure we hypothesize an upregulation due to functional or neuroanatomic chan ges (at least) in the frontotemporal cortex.