Loud Tones in Israeli Patients With Posttraumatic Stress Disorder

Physiologic Responses to

Arieh Y. Shalev, MD; Scott P. Orr, PhD; Tuvia Peri, MA; Shaul Schreiber, MD;

Orbicularis oculi (eye blink) electromyogram, skin conductance, and heart rate responses to 15 consecutive 95-dB, 500-millisecond, 1000-Hz tones with 0-millisecond rise and fall times were measured in 14 patients with posttraumatic stress disorder, 14 patients with other anxiety disorders, 15 mentally healthy subjects with past traumatic experiences, and 19 mentally healthy subjects with no trauma history. The patients with posttraumatic stress disorder showed significantly larger skin conductance and heart rate responses and a trend toward larger electromyogram responses to the tones than every other group. These effects were not \s=b\

explained by subjective anxiety, resting physiologic arousal, physiologic arousal preceding the tone trials, or initial physiologic responsivity. The group with posttraumatic stress disorder was the only one that failed to show habituation of skin conductance responses.

(Arch Gen Psychiatry. 1992;49:870-875)

of investigations1"8 have employed A number psychophysiologic techniques in the validation of disorder These studies have recent

posttraumatic

stress

(PTSD).

Roger K. Pitman,

MD

in cardiac and electrodermal activity, also follow the administration of startle-generating stimuli.12 These re¬ sponses are characterized by longer latencies and dura¬ tions than startle's muscular components. The skin con¬

ductance (SC) (or electrodermal) response may be a particularly good measure of arousal because its neural control is exerted exclusively via the sympathetic branch

of the autonomie nervous system.12 Another important dimension of the startle response is habituation, ie, the progressive decrease in response mag¬ nitude resulting from repeated presentations of a stimulus. Perhaps the most elementary form of learning, habituation is a manifestation of the organism's capacity to ignore stimuli that have lost their novelty.12 Habituation of the muscular and autonomie components of the acoustic star¬ tle response in normal humans typically occurs rapidly, ie, after a relatively small number of stimulus presentations.10 However, habituation of electrodermal responses to loud sounds has been reported to be slower in clinically anxious

(ANX) subjects.13"16

Given its classic status

as a

PTSD

symptom,17

it is

typically single DSM-HI-R criterion for PTSD, viz, "physiologic reactivity upon exposure to events that symbolize or resemble an aspect of the traumatic event."9*250' A relatively neglected area of psychophysio¬ logic investigation in PTSD is the nonspecific hyperreactivity that is also thought to characterize the disorder. One manifestation of this hyperreactivity is exaggerated startle response, which is also a DSM-III-R criterion for PTSD. The acoustic startle response is characterized by a sequence of flexor motor movements elicited by a sudden, intense auditory stimulus.10 It is typically measured in hu¬ mans as the magnitude of the muscular eyeblink reflex.11 However, autonomie nervous system changes, eg, changes

surprising that only a few reported psychophysiologic in¬ vestigations have addressed the startle response in PTSD. The first study18 reported paradoxically smaller orbicularis oculi electromyogram (EMG) (eye blink) responses in six children with PTSD compared with six normal children but less inhibitory prepulse modulation in the children with PTSD (however, see Pitman and Orr19). The second

November 27, 1991. Stress, Hadassah University Hospital and Hebrew University Medical School, Jerusalem, Israel (Drs Shalev and Schreiber and Mr Peri); and the Veterans Affairs Medical Center, Manchester, NH, and the Department of Psychiatry, Harvard Medical School, Boston, Mass (Drs Orr and Pitman). Read before the 144th Annual Meeting of the American Psychiatric

the PTSD group and six in the control group had been eliminated from the analysis. A fourth study22 did not find differences between eye-blink responses to loud noise stimuli in either placebo or yohimbine conditions in nine Vietnam veterans with PTSD and seven healthy control subjects. None of the above studies employed autonomie variables. However, a study23 not specifically designed to study startle found increased heart rate (HR) responses to tone stimuli in 12 Vietnam veterans with PTSD compared with six Vietnam combat veterans without PTSD. This

evaluated

a

Accepted for publication

From the Center for Traumatic

Association, New Orleans, La, May 14, 1991. Reprint requests from North America to Veterans Affairs Research Service, 228 Maple St, Manchester, NH 03103 (Dr Orr); from other locations, to Department of Psychiatry, Hadassah University Hospital, PO Box 12000, il-91120 Jerusalem, Israel (Dr Shalev).

study20

did not find differences between nine Vietnam veterans with PTSD and nine normal control subjects in rate of habituation of eye-blink response to acoustic and

investigation21 reported that the eye-blink response amplitude to 95-dB and 100-dB noise stimuli was significantly larger in a subgroup of 13 patients with PTSD compared with a subgroup of 12 con¬ trol subjects, after the data from seven nonresponders in tactile stimuli. The third mean

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ANOVA

M/F

Age, y Impact of event

Intrusion (0-21)

Avoidance (0-24) Modified Mississippi Scale (35-175)t

PTSD

ANX

TRA

NOTRA

(n=14)

(n=14)

(n=15)

(n=19)

11/3

4/10

10/5

9/10

35.0(9.1)

37.0(13.3)

32.5(12.7)

32.3(8.6)

17.9(5.7) 10.6(4.4)

...

...

7.3(5.0) 5.6(4.1)

I-1

...

F

df

0.6

3/58

.60

24.7 9.7

1/24 1/24