Basal adrenocortical activity and DST in electrodermally differentiated subgroups of panic patients

Twenty nine patients with panic disorder or agoraphobia with panic attacks were studied. The relationship between pre- and postdexamethasone serum cortisol level and electrodermal lability as reflected in electrodermal habituation rate and resting non-specific electrodermal activity was investigated. The frequency of non-suppression of cortisol following dexamethasone (DST non-suppressors) (at 5 micrograms/dl cut-off level) was 29.6% for the total group of patients. The basal plasma cortisol concentration showed positive correlation with the electrodermal habituation rate. The basal plasma cortisol level of slow habituator panic patients was significantly higher compared to rapid habituator patients, and it was above the normal range. On the contrary in rapid habituator panic patients the pre- and postdexamethasone cortisol difference was significantly less than in slow habituator patients, due to the normal basal plasma cortisol level and the relatively reduced rate of feedback suppression of cortisol following dexamethasone. Of the rapid habituator panic patients, 50% were non-suppressors following dexamethasone (at 5 micrograms/dl cut-off level). The above results might reflect two relatively different patterns of hypothalamic-pituitary-adrenal dysregulation in connection with two extremes of electrodermal habituation rate in panic patients.