Breath-holding in panic disorder.

In earlier studies, it was found that exogenous carbon dioxide administration provoked high anxiety in panic disorder (PD) patients, whereas healthy normals and patients suffering from other anxiety disorders were hardly affected. Breath-holding provides a simple method to induce endogenous CO2 accumulation. Fourteen PD patients, 14 patients suffering from other anxiety disorders, and 14 healthy controls were asked to hold their breath as long as possible. Apnea times appeared to be longer in the normal control group than in the other two groups. Using a one-tailed t test, a trend for a difference was found between the PD subjects and other anxiety patients, the PD patients having slightly lower values. No differences were found with respect to increase in anxiety during breath-holding or the ratio of apnea times before and after hyperventilation.