Parasympathetic reactivity to recalled traumatic and pleasant events in trauma-exposed individuals

Parasympathetic and heart rate (HR) reactivity to memories of traumatic and pleasant events were investigated in trauma-exposed individuals (n = 40). Vagal tone and HR were recorded before, during, and following recall of traumatic and pleasant events. Posttraumatic stress (PTS) was related to blunted parasympathetic reactivity among trauma-exposed individuals. Specifically, PTS severity was related to lower parasympathetic activation and lower recovery following trauma recall, and to lower parasympathetic activation (but not recovery) in response to a pleasant event recall. No association was observed between PTS severity and initial parasympathetic tone. However, PTS severity was associated with initial HR. Assessment of parasympathetic reactivity may enhance our understanding of the normative and pathological reactions to trauma and stress.