ELSEVIER Psychiatry Research 73 (1997) 103-107 PSYCHIATRY RESEARCH Brief report Physiologic responses to non-startling tones in Vietnam veterans with post-traumatic stress disorder Scott P. Orr a,b,*, Natasha B. Laskoa>b,Linda J. Metzgera9b, Roger K. PitmanaTb a zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Veterans Affairs Medical Center, Manchester, NH, USA bDepartment of Psychiatry, Harvard Medical School, Boston, MA, USA Received 14 February 1997; revised 19 August 1997; accepted 11 September 1997 zyxwvutsrqponmlkjihgfedcbaZ Abstract We evaluated eyeblink and autonomic reactivity to non-startling acoustic stimuli in a convenience sample of Vietnam combat veterans. Twenty veterans with current PTSD and 19 veterans who never had PTSD were exposed to 15 consecutive 86-dB, SOO-ms, lOO-Hz tones with 40-ms rise and fall times, while orbicularis oculi electromyogram (EMG), skin conductance (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. Results suggest that previous findings of larger HR responses to loud tones in PTSD extend to lower intensity, non-startling stimuli, but that the magnitude of the HR response appears smaller to the lower intensity stimuli. Previously observed differences in the magnitude of the eyeblink response and rate of decline of SC responses in PTSD to high intensity stimuli appear to disappear when using non-startling stimuli. 0 1997 Elsevier Science Ireland Ltd. Keywords: Post-traumatic stress disorder; Startle; Orienting; Psychophysiology; Veterans 1. Introduction When exposed to sudden, intense acoustic sti- muli, individuals with chronic post-traumatic *Corresponding author. VA Research Service, 228 Maple Street, Manchester, NH 03103, USA. stress disorder (PTSD) have been found to pro- duce larger heart rate (HR) (Paige et al., 1990; Shalev et al., 1992; Orr et al., 1995, 1997) and skin conductance (SC) responses (Shalev et al., 1992, 19971, have a slower rate of decline in SC re- sponse magnitude (relative habituation) (Shalev et al., 1992; Orr et al., 1995, 1997) and require more trials to reach a criterion of SC non-re- 01651781/97/$17.00 0 1997 Elsevier Science Ireland Ltd. All rights reserved. PrIso16s-1781(97)oollo-8