Sociodemographic and clinical characteristics of participating subjects.

BAI, Beck Anxiety Inventory; NA, not available; PDSS, Panic Disorder Severity Scale; SD, standard deviation; SSRI, selective serotonin re-uptake inhibitor. aχ2 statistics were used to analyze frequencies and t tests were used to test mean differences. bDuration of medication before scan of all patients was within a week. cThe approximate equivalent oral doses to 10 mg escitalopram are given. dThe approximate equivalent oral doses to 1 mg lorazepam are given.