NCT01627301 · Emory University
Sympathetic Overactivity in Post-traumatic Stress Disorder
(SO-PTSD)
What this study is about
Post-traumatic stress disorder (PTSD) is a highly prevalent anxiety disorder that is associated with an increased risk of cardiovascular (CV) disease and hypertension. One potential mechanism is overactivation of the sympathetic nervous system (SNS), both at rest and particularly during stress.
View original scientific description
Post-traumatic stress disorder (PTSD) is a highly prevalent anxiety disorder that is associated with an increased risk of cardiovascular (CV) disease and hypertension. One potential mechanism is overactivation of the sympathetic nervous system (SNS), both at rest and particularly during stress. This study will evaluate whether 8 weeks of daily DGB therapy or transcutaneous vagus nerve stimulation (tVNS) therapy improves SNS activity at rest and during stress.
Interventions
DEVICE
Device-Guided Breathing (DGB)
The RESPeRATE device will be used for 15 minutes of device-guided breathing daily for 8 weeks. The participant places the elastic belt with a respiration sensor around the upper abdomen, and wears earbuds for audio feedback. The device monitors the breathing rate, calculates inspiration and expiration times, and generates a personalized melody of two distinct ascending and descending tones for inhalation versus exhalation. Users effortlessly entrain their breathing pattern with the tones, and the device gradually guides the user to a prolonged expiration time and slower respiratory rate (to \< 10 breaths/minute). The device automatically stores usage data, allowing for quantification of adherence and performance.
DEVICE
Sham DGB
The sham device is identical to the DGB device, except it does not guide respiratory rates to slow down and instead maintains a rate of 14 breaths per minute. The sham device is used for 15 minutes per day for 8 weeks.
DEVICE
Transcutaneous Vagal Nerve Stimulation (tVNS)
tVNS is a noninvasive method that involves placing a device over the skin overlying the vagus nerve on the neck. The device delivers mild electrical stimulation, using transcutaneous electrical nerve stimulation (TENS) unit. The stimulation is increased until there is a vibration and slight muscle contraction in the lower face or neck. Then the stimulation is delivered for 2 minutes on the left side of the neck, and on the right side of the neck, for a total of 4 minutes. The tVNS device is used twice daily for 8 weeks.
DEVICE
Sham tVNS
Sham stimulation is delivered using a device that is identical to the gammaCore device but is programed to deliver a lower frequency that can be felt by the participant but does not actually stimulate the vagus nerve. The sham device is used twice daily for 8 weeks.
Primary outcome measures
Change in Muscle Sympathetic Nerve Activity (MSNA) Burst Frequency at Rest
Time frame: Baseline, Week 8
MSNA is assessed with microneurography where a tungsten microelectrode inserted in the nerve records sympathetic nerve activity.
Change in Baroreflex Sensitivity (BRS) at Rest
Time frame: Baseline, Week 8
Arterial baroreflex sensitivity (BRS) will be tested using pharmacologic manipulation of blood pressure at rest. BRS is assessed by measuring changes in MSNA and heart rate during arterial blood pressure changes induced by nitroprusside and phenylephrine.
Change in MSNA Burst Frequency While Under Mental Stress
Time frame: Baseline, Week 8
Mental stress will be induced by having participants complete mental arithmetic and with a combat virtual reality clip.
Change in BRS While Under Mental Stress
Time frame: Baseline, Week 8
Mental stress will be induced by having participants complete mental arithmetic and with a combat virtual reality clip. Arterial baroreflex sensitivity (BRS) will be tested using pharmacologic manipulation of blood pressure at rest and during mental stress.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- prehypertensive and normotensive veterans with PTSD, and prehypertensive and normotensive veterans without PTSD (controls)
Exclusion criteria
- heart or vascular disease
- illicit drug use within the last 6 months
- excessive alcohol use (\>2 drinks per day)
- autonomic dysfunction
- medications known to affect SNS (clonidine)
- treatment with monoamine oxidase (MAO) inhibitors within the last 14 days
- any serious systemic disease
Where
- Decatur, Georgia
Collaborators
US Department of Veterans Affairs
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jan 15, 2026 · Source of record for eligibility and locations