Abnormal sympathetic neural recruitment patterns and hemodynamic responses to cold pressor test in women with posttraumatic stress disorder

Abstract

The novel findings of the present study are that women with posttraumatic stress disorder (PTSD) have an augmented pressor response to the sympathoexcitatory stimulus of a cold pressor test (CPT) compared with healthy control subjects. Although integrated muscle sympathetic nerve activity burst responses were not significantly different between groups, total sympathetic action potential discharge in response to the CPT was markedly elevated in women with PTSD exhibiting increased firing of low-threshold axons as well as the recruitment of latent subpopulations of larger-sized axons that are otherwise silent at baseline. Aberrant autonomic circulatory control in response to sympathoexcitatory stimulus may in part explain the propensity toward developing hypertension and cardiovascular disease in this population.

Sex differences in post-traumatic stress disorder risk: autonomic control and inflammation

“…Although responses to the cold pressor test, a powerful sympathoexcitatory stimulus, was not augmented in PTSD patients in our previous study with predominantly male veterans [7], a recent study by Yoo et al found that total sympathetic action potential discharge in response to the cold pressor test was markedly elevated in women with PTSD [65]. Women with PTSD exhibited increased firing of low-threshold axons as well as increased recruitment of latent subpopulations of larger-sized axons that are otherwise silent at baseline [65]. This finding might suggest that women with PTSD exhibit greater aberrant neural circulatory control in response to a sympathoexcitatory stimuli.…”

“…They also reported a significant association between early onset augmented exercise pressor response and greater awake systolic blood pressure variability in women with PTSD but not in healthy controls [74], and concluded that the early onset exercise pressor reflex in women with PTSD might be one mechanism underlying the link between PTSD and greater CVD risk. Additionally, the same group of women with PTSD exhibited a greater BP response to the cold pressor test compared with control subjects [65]. Together, these data support high resting HR and hemodynamic reactivity in women with PTSD.…”

“…This finding might suggest that women with PTSD exhibit greater aberrant neural circulatory control in response to a sympathoexcitatory stimuli. Furthermore, in contrast to studies conducted in men, greater resting MSNA was reported in women with PTSD compared with healthy controls [65]. The same authors reported an earlier onset of MSNA activation during the first 30 seconds of static handgrip in women with PTSD compared with healthy controls [74].…”

“…Although the cold pressor test stimulates the nociceptors and can be used to evaluate the central integration of vasomotor sympathetic processes and their efferent pathways, the exercise pressor reflex elicited through static handgrip exercise is dependent on a feedback loop arising from mechano-and metabo-sensitive afferent nerve endings in the skeletal muscle [74]. These two studies by Yoo et al [65,74] expand our knowledge regarding physiological mechanisms that possibly contribute to an increased risk of developing CVD in women with PTSD.…”

“…One of the hallmarks of PTSD is increased psychophysiological arousal driven by the autonomic nervous system. As seen in Table 1, over-activation of the sympathetic nervous system (SNS) including changes in heart rate (HR) and blood pressure (BP) [4,8], catecholamines [64], muscle sympathetic nerve activity (MSNA) [7,65], and skin conductance [66], have been described in PTSD, while parasympathetic nervous system (PNS) activity [67] is blunted. We have previously also reported high MSNA reactivity to acute stress and impaired arterial baroreflex sensitivity [7] in individuals with PTSD.…”