Response patterns to repeated CO2 inhalation in individuals with high anxiety sensitivity

The present report extends previous work which has documented two distinct response patterns to repeated presentation of interoceptive cues (using CO2 inhalation) in PD patients [Beck, J. G. & Shipherd, J. C. (1997). Repeated exposure to interoceptive cues: does habituation of fear occur in panic disorder patients? Behaviour Research and Therapy, 35, 551-557]. We were interested in determining if these two patterns of fear habituation and sensitization would be noted in panic-naive individuals who reported high levels of Anxiety Sensitivity. A second aspect of this report examined whether attention to bodily sensations versus to neutral material would impact fear habituation and sensitization. Participants included 43 panic-naive individuals who scored at least 1 standard deviation above norms on the Anxiety Sensitivity Index. Results indicated that 37% of the sample reported habituation of fear, 47% reported fear sensitization and 16% demonstrated relatively stable fear levels across 12 inhalations of CO2 during session 1. The attentional manipulation did not exert a pronounced influence on anxiety, panic symptom severity, skin conductance, or heart rate in either Habituators or Sensitizers during session 2. These results are discussed in light of their relevance in understanding fundamental psychopathological processes underlying Panic Disorder.