Experimental affective symptoms in panic disorder patients.

Objective: To date, carbon dioxide (CO2) challenge tests in panic disorder (PD) patients have focused on anxiety as the sole outcome measure. This study assesses a broader range of symptoms in patients with PD.

Method: We administered a gas mixture of 35% CO2 and 65% oxygen (O2) to 25 patients with PD. Nine patients met the criteria for a comorbid major depressive disorder (MDD), and 16 did not. We assessed not only subjects' symptoms of anxiety but also their symptoms of depression and aggression.

Results: Baseline ratings did not differ across the 2 subgroups. Postchallenge ratings were higher for PD and MDD patients on all the assessed affective symptoms, except for specific panic symptoms.

Conclusion: These findings suggest that, in addition to anxiety, CO2 challenge induces depressive and aggressive symptoms, specifically in PD patients with comorbid depression.