Non-invasive Vagal Nerve Stimulation Paired with Stress Exposure in Posttraumatic Stress Disorder (PTSD)

Abstract

Non-invasive Vagal Nerve Stimulation (nVNS) is a new device that has promise for the study of vagal nerve physiology as well as clinical application in patients with psychiatric disorders. Posttraumatic stress disorder (PTSD) is a psychiatric disorder that can follow exposure to psychological trauma and is associated with intrusive memories, nightmares, avoidance, and problems with sleep and concentration. Exposure to reminders of the traumatic event can activate PTSD symptoms. We and others have shown changes in brain circuits in PTSD, including decreased medial prefrontal and increased amygdala function, as well as increased peripheral sympathetic and inflammatory responses, impaired autonomic tone, and an increased risk for coronary heart disease. In the current study, subjects with a history of exposure to psychological trauma undergo both trauma-specific and neutral stressors (math stress, public speaking) paired with nVNS or sham stimulation to the neck in conjunction with High Resolution Positron Emission Tomographic (HR-PET) with radiolabelled water imaging of the brain and measurement of stress biomarkers (e.g., inflammatory markers, cortisol, norepinephrine), as well as assessment of cardiovascular and autonomic parameters using wearable sensory devices. Pre-ejection Period (PEP) (the time interval between electrical depolarization of the left ventricle and the opening of the aortic valve) shortening is a marker of increased sympathetic tone, as is seen with stress. Other outcomes include peripheral vasoconstriction and rate pressure product (RPP). Preliminary findings show decreased inflammatory markers, blocked shortening of PEP, and increased medial prefrontal (anterior cingulate) function with nVNS paired to traumatic scripts but not sham controls. These findings suggest that nVNS has effects on both central and peripheral stress response systems in humans that may counteract the effects of stress. This research has implications for new treatments involving electrical stimulation in PTSD.