Autonomic characteristics of agoraphobia with panic attacks.

We compared electrodermal and heart rate measures of autonomic activation between patients meeting DSM-III criteria for agoraphobia with panic attacks and controls in terms of tonic level, reactivity to various types of stimuli, recovery, habituation, and spontaneous variability. The most striking differences between groups in the laboratory were higher tonic levels of skin conductance and heart rate among patients. Patients' heart rates were also tonically elevated in a test situation outside the laboratory. Certain measures of habituation and spontaneous variability also differed between groups, but there were only weak and inconsistent differences in reactivity to, or recovery from, stimuli with diverse qualities of novelty, startlingness, intensity, or phobicity. The elevated activation levels may be signs of a chronic state or may be phobic responses to the testing situations. A minority of patients failed to show these elevated levels.