Acute dissociation and cardiac reactivity to script-driven imagery in trauma-related disorders

Background: Potential acute protective functions of dissociation include modulation of stress-induced psychophysiological arousal. This study was designed to explore whether acute dissociative reactions during a stress experiment would override the effects of reexperiencing. Methods: Psychophysiological reactions during exposure to script-driven trauma imagery were studied in relation to acute responses of reexperiencing and dissociative symptoms in 61 patients with histories of exposure to a variety of traumas. Acute symptomatic responses were assessed with the Responses to Script- Driven Imagery Scale (RSDI), and participants were divided into four groups by median splits of RSDI reexperiencing and dissociation subscale scores. Results: In a comparison of the high RSDI reexperiencing groups with low versus high acute dissociative symptoms, the high dissociators exhibited significantly lower heart rate (HR) during trauma script and a significantly smaller script-induced decrease in parasympathetic cardiac activity. HR reactivity to the trauma script was negatively correlated with acute dissociative symptom severity. Conclusions: Acute dissociative reactions are a potential moderator of response to experimental paradigms investigating psychologically traumatized populations. We therefore suggest that future research on psychophysiological stress reactions in traumatized samples should routinely assess for acute dissociative symptoms.