Psychophysiological factors in panic disorder.

Panic disorder patients were compared with normal subjects during intravenous infusion of sodium lactate, isoproterenol, and placebo. Panic attacks meeting the criteria of the Diagnostic and Statistical Manual, vol. 3 [American Psychiatric Association, 1980] occurred during all three conditions in patients and during the lactate and isoproterenol infusions in normals. Patients had significantly higher average levels of skin conductance, heart rate and state anxiety, and significantly lower finger temperatures compared to normal subjects. However, no measure reliably differentiated panic attacks from nonattack periods. It is concluded that the peripheral physiologic responses investigated are neither necessary nor sufficient for the occurrence of panic attacks. It is possible that reports of these attacks represent phobic responses to intense anxiety.