Posttraumatic stress, heart rate variability, and the mediating role of behavioral health risks

Posttraumatic stress disorder (PTSD) has been linked to reduced heart rate variability (HRV), which is in turn a risk factor for cardiovascular disease and death. Although hyperarousal and anxiety are thought to underlie this association, behavioral health risks, including smoking, alcohol dependence, obesity, and sleep disturbance, represent potential mechanisms linking PTSD and HRV.

To test this hypothesis, short-term laboratory-based and 24-hour ambulatory measures of HRV were collected from 227 young adults (18-39 years), 107 of whom were diagnosed as having PTSD. Latent variable modeling was used to assess the relationship of PTSD symptoms with HRV along with potential behavioral health mediators.

PTSD symptoms were associated with reduced HRV (β = -0.21, p = .002). However, this association was reduced in models that adjusted for cigarette consumption and history of alcohol dependence and was rendered nonsignificant in a model adjusting for sleep disturbance. Independent mediation effects were deemed significant via bootstrapping analysis. Together, the three behavioral health factors (cigarette consumption, history of alcohol dependence, and sleep disturbance) accounted for 94% of the shared variance between PTSD symptoms and HRV. Abdominal obesity was not a significant mediator.

These results indicate that behavioral factors-specifically smoking, alcohol overuse, and sleep disturbance-mediate the association between PTSD and HRV-based indices of autonomic nervous system dysregulation. Benefits from psychiatric and psychological interventions in PTSD may therefore be enhanced by including modification of health behaviors.