Dark-enhanced startle responses and heart rate variability in a traumatized civilian sample: putative sex-specific correlates of posttraumatic stress disorder - PubMed (original) (raw)

Dark-enhanced startle responses and heart rate variability in a traumatized civilian sample: putative sex-specific correlates of posttraumatic stress disorder

Asante Kamkwalala et al. Psychosom Med. 2012 Feb-Mar.

Abstract

Objective: Trauma is associated with increased risk for anxiety disorders such as posttraumatic stress disorder (PTSD). To further understand biologic mechanisms of PTSD, we examined the dark-enhanced startle response, a psychophysiological correlate of anxiety, and heart rate variability (HRV) in traumatized individuals with and without PTSD. The associations of these measures with PTSD may be sex-specific because of their associations with the bed nucleus of the stria terminalis, a sexually dimorphic brain structure in the limbic system that is approximately 2.5 times larger in men than in women.

Methods: The study sample (N = 141) was recruited from a highly traumatized civilian population seeking treatment at Grady Memorial Hospital in Atlanta, Georgia. Psychophysiological responses during a dark-enhanced startle paradigm task included startle magnitude, assessed by eyeblink reflex, and measures of high-frequency HRV, during light and dark phases of the startle session.

Results: The startle magnitude was higher during the dark phase than the light phase (mean ± standard error = 98.61 ± 10.68 versus 73.93 ± 8.21 μV, p < .001). PTSD was associated with a greater degree of dark-enhanced startle in women (p = .03) but not in men (p = .38, p interaction = .48). Although HRV measures did not differ between phases, high-frequency HRV was greater in men with PTSD compared with men without PTSD (p = .02).

Conclusions: This study demonstrates that the dark-enhanced paradigm provides novel insights into the psychophysiological responses associated with PTSD in traumatized civilian sample. Sex differences in altered parasympathetic and sympathetic function during anxiety regulation tasks may provide further insight into the neurobiological mechanisms of PTSD.

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Conflict of interest statement

The authors report no conflicts of interest.

Figures

Figure 1

Figure 1

Dark-enhanced startle session diagram. Black lines represent acoustic startle probes (108 dB) delivered during each segment of the session. The order of light and dark phases within each block was counterbalanced across subjects.

Figure 2

Figure 2

The figure shows diagnostic group and sex with mean dark-enhanced startle (difference score between dark and light phases) (A) and RSA (HF-HRV) (B). PTSD = posttraumatic stress disorder; RSA = respiratory sinus arrhythmia; HF-HRV = high-frequency heart rate variability.

Comment in

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