Increased epoch-to-epoch parasympathetic cardiac regulation in participants with posttraumatic stress disorder compared to those with panic disorder and control participants

Research on the link between respiratory sinus arrhythmia (RSA) and posttraumatic stress disorder (PTSD) has largely focused on average levels of RSA. However, given that rapid shifts in parasympathetic tone are necessary to maintain adaptive cardiac variability, the exclusive focus on these tonic estimates provides an incomplete quantification of parasympathetic cardiac regulation. The present study is a secondary analysis of previously published data. This analysis aimed to address this limitation by examining the dynamic regulatory effect of the parasympathetic nervous system on heart rate. As such, we examined epoch-to-epoch parasympathetic cardiac regulation – operationalized as the lagged relationship between RSA and heart rate (HR) across consecutive 30-s epochs – across a single night in participants with PTSD, panic disorder (PD), comorbid PTSD and PD (PTSD+PD), and healthy controls. Electrocardiogram and respiratory signals were continuously recorded from 23 participants with PTSD, 14 with PD, 16 with PTSD+PD, and 16 control participants over a single night of sleep in a laboratory setting. No group differences in tonic RSA were observed; however, participants with PTSD only and PTSD+PD exhibited significantly greater epoch-to-epoch parasympathetic cardiac regulation over the night than those with PD only and control participants. Moreover, greater severity of hyperarousal symptoms was significantly associated with increased epoch-to-epoch parasympathetic cardiac regulation among participants with PTSD only and PTSD+PD. These data provide preliminary evidence for an upregulatory parasympathetic response to self-reported hyperarousal in participants with PTSD only and PTSD+PD reflected by increased epoch-to-epoch parasympathetic cardiac regulation.