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.

Anxiety sensitivity and modulation of the serotonergic system in patients with PD.

Anxiety sensitivity, i.e., the fear of anxiety-related bodily sensations, is one of the most studied cognitive variables in panic disorder (PD). However, the effects of selective serotonergic antipanic agents on this variable have not yet been investigated. The present study examines the effects of 6 weeks of treatment with citalopram on anxiety sensitivity in patients with PD. Twenty patients entered the study. On day 0, before starting drug treatment, after 1 week and after 6 weeks of treatment, each patient was evaluated with the Anxiety Sensitivity Index (ASI); the severity of clinical symptomatology was assessed with standardized psychometric scales. Results showed a significant reduction of anxiety sensitivity after 6 weeks of treatment. There was a significant correlation between decrease of anxiety sensitivity and anticipatory anxiety, while no correlations were found between panic attacks and agoraphobic avoidance. These results suggest that antipanic drug treatment decreases anxiety sensitivity.