PHYSIOLOGICAL-RESPONSES TO NON-STARTLING TONES IN VIETNAM VETERANS WITH POSTTRAUMATIC-STRESS-DISORDER

We evaluated eyeblink and autonomic reactivity to non-startling acoust ic stimuli in a convenience sample of Vietnam combat veterans. Twenty veterans with current PTSD and 19 veterans who never had PTSD were exp osed to 15 consecutive 86-dB, 500-ms, 100-Hz tones with 40-ms rise and fall times, while orbicularis oculi electromyogram (EMG), skin conduc tance (SC) and heart rate (HR) responses were measured. PTSD subjects had higher resting HR levels and produced larger averaged HR responses across the 15 tone presentations compared to non-PTSD subjects. Skin conductance and EMG responses did not differ between the groups. Resul ts suggest that previous findings of larger HR responses to loud tones in PTSD extend to lower intensity, non-startling stimuli, but that th e magnitude of the HR response appears smaller to the lower intensity stimuli. Previously observed differences in the magnitude of the eyebl ink response and rate of decline of SC responses in PTSD to high inten sity stimuli appear to disappear when using non-startling stimuli. (C) 1997 Elsevier Science Ireland Ltd.