Response to repeated CO2 in individuals with elevated anxiety sensitivity:Replication with 20% CO2

The present report replicates and extends previous work examining response patterns to repeated presentation Of CO2. In previous studies, two distinct response patterns to repeated presentation of 35% CO2 were noted, represen ting habituation and nonhabituation of anxiety. In this report, 21 particip ants who had never experienced a panic attack but who reported high levels of anxiety sensitivity were presented with 12 trials of 20% CO2, followed b y a trial involving inhalation of room air (to examine dishabituation) and two more trials of 20% CO2. Results indicated that 67% of the sample report ed habituation of anxiety. Reductions in anxiety across inhalations were pa ralleled by changes in tidal volume, perceived panic symptom severity, and feelings of panic. Notable dishabituation was observed in the nonhabituatio n sample. Results are discussed in the light of basic learning processes un derlying the treatment of Panic Disorder (PD). (C) 2001 Elsevier Science Lt d. All rights reserved.