Probing the neurocardiac circuit in trauma and posttraumatic stress.

The neurocardiac circuit is integral to physiological regulation of threat and trauma-related responses. However, few direct investigations of brain-behavior associations with replicable physiological markers of PTSD have been conducted. The current study probed the neurocardiac circuit by examining associations among its core regions in the brain (e.g., insula, hypothalamus) and the periphery (heart rate [HR], high frequency heart rate variability [HF-HRV], and blood pressure [BP]). We sought to characterize these associations and to determine whether there were differences by PTSD status. Participants were N = 315 (64.1 % female) trauma-exposed adults enrolled from emergency departments as part of the prospective AURORA study. Participants completed a deep phenotyping session (e.g., fear conditioning, magnetic resonance imaging) two weeks after emergency department admission. Voxelwise analyses revealed several significant interactions between PTSD severity 8-weeks posttrauma and psychophysiological recordings on hypothalamic connectivity to the prefrontal cortex (PFC), insula, superior temporal sulcus, and temporoparietaloccipital junction. Among those with PTSD, diastolic BP was directly correlated with right insula-hypothalamic connectivity, whereas the reverse was found for those without PTSD. PTSD status moderated the association between systolic BP, HR, and HF-HRV and hypothalamic connectivity in the same direction. While preliminary, our findings may suggest that individuals with higher PTSD severity exhibit compensatory neural mechanisms to down-regulate autonomic imbalance. Additional study is warranted to determine how underlying mechanisms (e.g., inflammation) may disrupt the neurocardiac circuit and increase cardiometabolic disease risk in PTSD.
Competing Interests: Declaration of competing interest Dr. Neylan reports consultation for Jazz Pharmaceuticals; Dr. Rauch reports royalties from Oxford University Press, the American Psychiatric Publishing Inc., and Springer Publishing royalties; Dr. McLean reports consultation for Walter Reed Army Institute for Research and for Arbor Medical Innovations; Dr. Kessler reports consultation for Cambridge Health Alliance, Canandaigua VA Medical Center, Holmusk, Partners Healthcare, INC Mirah, PYM, and Roga Sciences; Dr. Koenen reports royalties from Guilford Press and Oxford University Press; Dr. Ressler reports consultation for Bioxcel, Bionomics, Acer, and Jazz Pharma; All other authors report no biomedical financial interests or potential conflicts of interest.
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