BACKGROUND

Individuals with posttraumatic stress disorder (PTSD) demonstrate alterations in autonomic responses to fear conditioning, such as exaggerated startle and poor fear inhibition. However, there is a paucity of research on fear conditioning among individuals with PTSD and dissociative symptoms, which represents 10-30% of those with PTSD. The current study used a fear-potentiated startle (FPS) conditioning paradigm to examine autonomic responses among women with PTSD and a range of dissociative symptoms.

METHODS

Participants included 39 women with PTSD and dissociation, and 53 women with PTSD with unknown levels of dissociation. The FPS paradigm consisted of conditioned stimuli associated and not associated with an aversive unconditioned stimulus. FPS response (eyeblink startle), electrocardiogram (ECG), and skin conductance response (SCR) were collected during the FPS paradigm.

RESULTS

Compared to the PTSD-unknown dissociation sample, the PTSD-dissociation sample demonstrated significantly lower FPS during the last block of conditioning. Among the PTSD-dissociation sample, higher dissociation scores were associated with decreased FPS and SCR, and higher respiratory sinus arrhythmia (derived from ECG).

CONCLUSIONS

Results suggest that autonomic responses to fear conditioning differ depending on the presence and severity of dissociative symptoms. Given that treatment response may differ depending on dissociative symptoms, it is important to understand the mechanisms that underlie different subtypes of PTSD and that may affect treatment response and outcome.