Auditory startle response in trauma survivors with posttraumatic stress disorder: A prospective study

Objective: Previous studies have shown elevated autonomic responses to star tling tones in trauma survivors with chronic posttraumatic stress disorder (PTSD). The origin of these abnormal responses is obscure. The present stud y attempted to clarify this issue by prospectively evaluating responses to sudden, loud tones in individuals who arrived at a hospital emergency room after psychologically traumatic events. Method: By using a previously estab lished protocol, autonomic and muscular responses to the tones were evaluat ed at 1 week, 1 month, and 4 months after the traumatic event. Structured d iagnostic interviews performed at 4 months classified subjects into groups with (N=36) and without (N= 182) PTSD, which were further subdivided accord ing to the presence or absence of major depressive disorder as follows: nei ther PTSD nor depression (N=166), depression alone (N=16), PTSD alone (N=21 ), and both PTSD and depression (N=15). Results: The groups showed comparab le physiological responses to the tones at 1 week posttrauma. However, at 1 and 4 months posttrauma, the subjects with PTSD showed a greater heart rat e response and required more stimulus trials to reach the criteria of skin conductance and orbicularis oculi electromyogram nonresponse. These finding s were not significantly influenced by comorbid depression and were not exp lained by the severity of the traumatic event or by the intensity of the in itial symptoms. Conclusions: Differences in physiological response to start ling tones develop along with PTSD in the months that follow a traumatic ev ent. This pattern supports the theories that associate PTSD with progressiv e neuronal sensitization.