Impact of posttraumatic stress symptom dimensions on amygdala reactivity to emotional faces

Abstract

Posttraumatic stress disorder (PTSD) is highly prevalent and associated with impairment, even at the subthreshold level. It is therefore important to identify biological processes that contribute to the pathophysiology of posttraumatic stress symptoms (PTSS). Although neuroimaging research has highlighted the importance of heightened amygdala reactivity to aversive stimuli in PTSS, not all studies have yielded evidence of this relationship. Given that PTSS is comprised of four, factor analytically distinct dimensions of symptoms – re-experiencing, avoidance, hyperarousal, and negative cognitions and mood – it is possible that heightened amygdala reactivity to aversive stimuli is specific to certain PTSS clusters. In a sample of 45 trauma-exposed individuals, the present study therefore examined how specific PTSS clusters relate to amygdala responding during functional magnetic resonance imaging (fMRI) to both negative and positive emotional faces during a well-validated social-emotional task, the Emotional Face Assessment Task (EFAT). Results indicated that hyperarousal symptoms were positively associated with left amygdala reactivity across all emotional face conditions. There was no interaction of hyperarousal by condition (i.e., fearful, sad, angry, or happy faces), and other PTSS clusters were not associated with amygdala reactivity. These results indicate that the hyperarousal cluster of PTSS may have a unique relationship with amygdala reactivity to socioemotional information. The results also corroborate a growing literature suggesting that trauma-exposed individuals characterized by high PTSS hyperarousal symptoms may display exaggerated psychophysiological reactivity to appetitive and aversive stimuli.