Auditory startle response in firefighters before and after trauma exposure.

Objective: Although previous psychophysiological studies have revealed heightened muscular and autonomic responses in individuals with posttraumatic stress disorder (PTSD), these studies have not permitted inferences about whether the abnormal responses are a vulnerability factor or are acquired following trauma. The present study reports the first prospective psychophysiological investigation, to the authors' knowledge, of posttraumatic stress responses by prospectively evaluating the auditory startle response in firefighters before and after trauma exposure.

Method: Orbicularis oculi (eye blink) electromyograms and skin conductance responses to 15 100-dB acoustic startle stimuli were assessed in 84 trainee firefighters before trauma exposure. After commencement of active duty, 35 firefighters were reassessed within 4 weeks of exposure to a traumatic event, and 36 firefighters were reassessed as a comparison group that was not exposed to trauma.

Results: In the trauma-exposed group, pretrauma physiological activity was predictive of posttrauma acoustic startle responses. Pretrauma skin conductance response to startle was also predictive of posttraumatic stress severity.

Conclusions: These results provide initial support for elevated startle response being a vulnerability factor for posttraumatic stress responses.