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

OBJECTIVE: 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. METHODS: 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. RESULTS: PTSD symptoms were associated with reduced HRV (ß = -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. CONCLUSIONS: 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.

Orthostatic hypotension in young adults with and without posttraumatic stress disorder.

The purpose of this research is (a) to evaluate differences in orthostatic hypotension (OH) among young adults with and without posttraumatic stress disorder (PTSD) and (b) to examine whether group differences may be attributable to behavioral risk factors frequently associated with PTSD. Volunteers and U.S. veterans 18 to 39 years old (N = 222) completed a semistructured interview assessment of PTSD status. Direct measurements were obtained for supine and standing systolic and diastolic blood pressure at study visits, as well as height and weight, from which body mass index (BMI) was calculated. After controlling for use of psychotropic medications, a logistic regression model revealed that PTSD status was positively associated with OH, such that participants with PTSD were at 4.51 greater odds of having OH than control participants. Moreover, this effect was partially mediated by lifetime alcohol dependence (bootstrapped 95% confidence interval [-0.83, -0.20]). Overall, PTSD may pose a significant risk for OH among younger adults. In the present sample, this relationship was primarily driven by the disproportionately high history of alcohol dependence among individuals with PTSD. These results suggest that traditional therapy for PTSD should be coupled with treatment for alcohol dependency, when applicable, to reap both psychological and physiological benefits.