Acute Effects of Device-Guided Slow Breathing on Neurocardiovascular Activity in Post-Traumatic Stress Disorder Open Access

Abstract

 Post-traumatic stress disorder (PTSD) is associated with an increased risk for developing hypertension and cardiovascular (CV) disease, but the mechanisms underlying this risk remain unknown. Patients with PTSD have higher resting heart rate and blood pressure (BP) and decreased heart rate variability (HRV), suggesting a state of increased sympathetic nervous system (SNS) and decreased parasympathetic nervous system (PNS) activity that could contribute to increased CV risk. Therefore, SNS overactivity and decreased PNS activity could serve as putative therapeutic targets to improve CV risk in PTSD. Prior studies have shown that device-guided slow breathing (DGB) may lower BP and SNS activity in hypertensive patients; however, the potential beneficial effects of DGB on PNS have not previously been explored in PTSD. We hypothesized that DGB will lower BP and improve autonomic function in PTSD patients. We recruited 27 Veterans with PTSD and 16 Veterans without PTSD (controls). The PTSD group was randomly assigned to the DGB (PTSD+DGB, N=16) during which respiratory rates were monitored and lowered using a biofeedback device to sub-physiologic levels (~5 breaths/min) versus an identical sham device (PTSD+SHAM, N=11) in which respiratory rates were held at a normal rate of 14 breaths/min. All control participants without PTSD were assigned to the DGB device (CON+DGB, N=16). Continuous EKG and beat-to-beat arterial blood pressure were monitored for 10 minutes at rest, followed by 10 minutes of breathing with either DGB or SHAM. From baseline to the end of 10 minutes of DGB, the PTSD+DGB group had a significant reduction in systolic blood pressure (SBP, -12±3 mmHg, p<0.001) and mean arterial pressure (MAP, -7±2 mmHg, p=0.003), and a trend towards reduction in diastolic blood pressure (DBP, -4±2 mmHg, p=0.0565). In the CON+DGB group, we observed a significant reduction in SBP (-11±4 mmHg, p=0.0105), and a trend towards reduced DBP and MAP. There was no significant reduction in SBP, DBP, and MAP with the sham device in PTSD patients. There was no significant change in HR, RMSSD, pNN50, and HF either with DGB or SHAM. DGB acutely lowers blood pressure in PTSD patients and Controls, but does not improve PNS measures. Long-term studies are needed to determine if DGB could represent a novel therapeutic intervention to improve hemodynamics and autonomic physiology in PTSD patients.

Table of Contents

Introduction …………..…………..…………..…………..…………..…………..………..…….. 1

Methods and Protocol …………..…………..…………..…………..…………..………….…... 15

Data Analysis and Statistics …………..…………..…………..…………..…………..………... 21

Results …………..…………..……………..………..…………..…………..…………..……… 24

Discussion/Conclusion ……….....…………..…………..…………..…………..…………..….. 35

Limitations …………..…………..…………..……………..…………..…………..………..…. 41

Future directions …………..…………..…………..…………..…………..…………..……….. 43

References …………..…………..…………..…………..…………..…………..……………… 44

About this Honors Thesis

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School	Emory College
Department	Biology
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Biology, Physiology
Keyword	PTSD, cardiovascular risk, hypertension, slow breathing, device-guided slow breathing, DGB, acute effects
Committee Chair / Thesis Advisor	Park, Jeanie, Emory University
Committee Members	Jensen, Robert, Emory University Corces, Victor, Emory University

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