Response to Hyperventilation and 5.5% CO sub 2 Inhalation of Subjects With Types of Specific Phobia, Panic Disorder, or No Mental Disorder

Antony, Martin M. PhD
Brown, Timothy A. PsyD
Barlow, David H. PhD

Received July 19, 1995; revisions received Jan. 17 and March 18, 1997; accepted April 11, 1997. From the Clarke Institute of Psychiatry and the University of Toronto, Canada; the State University of New York at Albany; and the Center for Anxiety and Related Disorders, Boston University. Address reprint requests Dr. Antony, Anxiety Disorders Clinic, Clarke Institute of Psychiatry, 250 College St., Toronto, Ont., Canada M5T 1R8.
The authors thank Andrea Liss, the staff at the Center for Stress and Anxiety Disorders, State University of New York at Albany, and especially Ann Conklin, for their help with this study.

American Journal of Psychiatry 154(8):p 1089-1095, August 1997.

Objective

This study tested the hypothesis that compared to other DSM-IV specific phobia types, situational specific phobias have more in common with panic disorder and agoraphobia.

Method

Responses to hyperventilation and CO₂ inhalation were compared across groups of patients with the four main DSM-IV specific phobia types, a group with panic disorder, and a group of comparison subjects with no anxiety disorder (N=15 per group).

Results

Although these challenges have been shown previously to distinguish patients with panic disorder from other groups, no groups differed significantly in their responses to hyperventilation. In addition, whereas the patients with panic disorder responded more to the CO₂ challenge than did the normal subjects, the specific phobia groups did not differ from one another or from the other groups on most measures. For the few CO₂ measures on which specific phobia groups differed, patients with situational and natural environment phobias showed the greatest response.

Conclusions

Overall, these findings provided only limited support for the hypothesis that situational specific phobias are related to panic disorder.

(Am J Psychiatry 1997; 154:1089-1095)