Onset of panic disorder.

The situations in which the first panic attack occurred were investigated in 44 patients affected by panic disorder. Although the first panic attack was reported to be unexpected and no avoidance was present before it, 75.8% of patients (N = 22) with panic disorder with agoraphobia had their first panic attack in phobogenic situations, compared with 20% of patients (N = 3) with panic disorder without agoraphobia.