The Role of Anxiety Sensitivity and Expectancy Manipulation on Panic-Like Response to the 35% CO2 Challenge in Healthy Subjects.

BACKGROUND

The 35% CO2 challenge is a well-established method triggering panic attacks under laboratory-controlled conditions. There is an ongoing debate whether single or the joined effects of the instructional set and anxiety sensitivity (AS) can alter the outcome of the challenge.

OBJECTIVES

The present study investigated the effects of instruction manipulation and AS on panic-like response to the 35% CO2 challenge.

METHODS

Eighty healthy subjects, with high or low levels of AS, were randomized into 4 groups based on standard/manipulated instructional sets as well as 35% CO2 mixture/room air inhalation. Subjects filled in the Visual Analogue Scale of Anxiety (VAAS), the Visual Analogue Scale of Fear (VAS-F), the VAS of Discomfort (VAS-D), and the Panic Symptom List (PSL). Blood pressure and heart rate were measured at pre- and posttest.

RESULTS

Hierarchical multiple regression analyses showed greater psychological responses at VAAS, VAS-F, VAS-D, and PSL and higher systolic blood pressure under 35% CO2 challenge if compared to room air inhalation while instructional set and AS did not influence the response.

CONCLUSIONS

The present study confirms that neither instructional test nor AS alter the outcome of the 35% CO2 challenge.