Assessment of Heart Rate Variability as a Measure of Acute Psychological Stress in Ambulatory Settings Open Access

Sundar, Manasvi (Spring 2021)

Permanent URL: https://etd.library.emory.edu/concern/etds/qb98mg62f?locale=en
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Abstract

Background

While previous studies have shown that Post Traumatic Stress Disorder (PTSD) is associated with reduced Heart Rate Variability (HRV), most studies are cross sectional in design, limiting the ability to make causal inferences and illustrate temporality of the association. Although HRV is often measured in ambulatory settings, few studies have adjusted for the effect of physical movement on HRV. We sought to examine the relationship between everyday PTSD symptoms severity and HRV, adjusting for physical activity assessed using actigraphy. 

Methods

Study participants were male twins from the Vietnam Era Twin Registry. HRV was collected using ambulatory ECG monitoring patch that participants wore for up to 8 days. They also wore an Actiwatch device on their wrist which collected physical activity counts. Daily PTSD symptoms were ascertained using PTSD Checklist for DSM-V (PCL-5). Low Frequency HRV (LF-HRV) and physical activity counts were log transformed and standardized, and PCL score was standardized. Multilevel Models were used to assess the associations between PTSD symptoms and LF-HRV, adjusting for physical activity counts, PTSD diagnosis, and other confounders. In addition to estimating the association among individual participants, between and within twin pair effects were analyzed.

Results

The analytic sample (n = 106) consisted of men with a mean age of 68.0 years (SD = 2.6) and 18.8% of the sample had current or past PTSD. Examining the relationship among individual subjects, daily PTSD symptoms measured by PCL score was significantly associated with lower LF-HRV on a log scale (p<0.0001) and the relationship remained significant after adjusting for potential confounders. One standardized unit increase in PCL score was associated with 0.03 decrease in standardized log LF-HRV after adjusting for confounders. The within pair effect for daily PCL score was significantly associated with lower log LF-HRV values in both unadjusted and adjusted models (p < 0.0001). 

Conclusion

We observed that higher levels of Post Traumatic Stress Disorder (PTSD) symptoms severity recorded everyday was associated with reduced Heart Rate Variability indicating impaired autonomic regulation, controlling for potential confounders, genetic, and familial factors. Furthermore, this relationship was independent of PTSD diagnosis, showing that acute measures of psychological stress account for autonomic dysfunction independent of chronic stress conditions. 

Table of Contents

Chapter I: Background.........1

Chapter II: Manuscript........4

Abstract.............................4

Introduction......................5

Methods............................7

Results.............................11

Discussion.......................12

References.......................16

Tables.............................23

Chapter III: Summary.......26

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