Acoustic startle response in panic disorder

The amygdala and the limbic system are important in inducing a fear reaction; if this "fear network" is involved in panic disorder, panic patients might be more sensitive to fear stimuli than healthy subjects. We compared the startle response with an aversive stimulus in a sample of 29 patients with panic disorder and a sample of 29 healthy controls. The intensity of the startle response, induced by a series of aversive loud (100 dB) sounds, was measured by skin conductance recording in each subject. No statistically significant differences between the two groups were found in either the baseline level of skin conductance or in the response to the stimuli. Nonetheless, panic patients reported significantly higher levels of baseline anxiety measured by the State-Trait Anxiety Inventory. In conclusion, our data do not support the hypothesis that patients with panic disorder are characterised by a hyperreactivity, as measured by the skin conductance response, to fearful sudden stimuli or, at least, to those delivered to the auditory system.