Fear Learning in Veterans With Combat-Related PTSD Is Linked to Anxiety Sensitivity: Evidence From Self-Report and Pupillometry

Abstract

Several studies have observed heightened Pavlovian fear conditioning in PTSD. However, it is unclear how fear conditioning in PTSD is related to risk factors for the disorder, such as anxiety sensitivity. Fifty-one combat-exposed veterans (20 with PTSD, 31 without PTSD) completed a differential fear conditioning task in which one colored rectangle (CS+) predicted a loud scream (US), whereas a different colored rectangle (CS-) predicted no US. Veterans with PTSD were characterized by greater anxiety to the CS+ but not the CS- during acquisition and extinction, and greater US expectancy during the CS+ but not the CS- at extinction. Also, veterans with PTSD had greater pupil dilation to both CSs at extinction, but not at acquisition. Anxiety sensitivity was correlated with anxiety and US expectancy in response to the CS+, but not the CS-, at both acquisition and extinction, and also with pupil diameter to both the CS+ and CS- at extinction. Nearly all of these relations held when covarying for PTSD symptoms and trait anxiety. These findings suggest that increased fear conditioning in PTSD may be related to elevated anxiety sensitivity.