Sympathetic Overactivity in Post-traumatic Stress Disorder

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.

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.

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.

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.