Understanding Non-invasive Vagus Nerve Stimulation Effects in PTSD

SPARK-VNS: Facilitating Adaptive Posttraumatic Processing With Non-Invasive Vagus Nerve Stimulation

The goal of this study is to determine how non-invasive brain stimulation (delivered through the ear called vagus nerve stimulation) affects fear learning processes in people who have experienced psychological trauma. To answer these questions, we measure bodily responses (heart rate, sweat, startle) and questionnaires. The main questions it aims to answer are:

Does non-invasive vagus nerve stimulation help reduce anxious arousal? Does non-invasive vagus nerve stimulation help dampen learned fear?

This study aims to determine how non-invasive brain stimulation (delivered through the ear) affects learning processes. During this study, participants who have experienced a trauma will be asked to complete surveys and come to the lab for about 7 hours across four lab visits. Researchers will measure body responses (heart rate, skin conductance, startle), while the ear is stimulated. Participants also will be asked to complete a startle task. The study is at the Wayne State University Tolan Park Research Clinic. Participants will be compensated for their time. To be eligible, participants must be 18-70 years old, have experienced or witnessed a traumatic event, be able to commit 7 hours of time to the study, and be able to wear sensors on their hands, arms, and head and sit quietly at a computer.

Aim 1. Establish feasibility and acceptability of taVNS in a diverse sample of Detroit metro residents with symptoms of posttraumatic stress. It is hypothesized that taVNS delivery will be feasible and acceptable for individuals with trauma exposure and PTS symptoms, and that there will be no difference in acceptability/tolerability between the active and sham conditions.

Aim 2. Establish the effects of active versus sham taVNS on physiological indicators during fear extinction. It is hypothesized that active compared to sham taVNS will a) result in facilitation of fear extinction, and b) show greater modulation of physiological responding. Exploratory Aim: Data will be explored for individual differences (affective blunting, hyperarousal, impaired discrimination of conditioned stimuli) which moderate taVNS effects.

This proposed project will determine how taVNS delivered at higher doses than have been previously administered influence the course of adaptive posttraumatic processing in a sample with trauma exposure, while evaluating the psychophysiological profile in multiple contexts.

Inclusion Criteria:

1. Ages 18-80
2. Fluent in English
3. Experience with a DSM-5 Criterion A trauma (LEC-5)
4. Probable PTSD (PCL-5 ≥ 32)

Exclusion Criteria:

1. Visual or Auditory impairment
2. Major injury at time of screen or study procedures
3. Taking ≥20 mg morphine per day
4. Current substance use or intoxication (12-panel drug test)
5. Intellectual disability (MoCA)
6. Self-inflicted injury
7. Occupational injury
8. Prisoner
9. Ongoing domestic violence
10. Pregnant or breastfeeding
11. Contraindications for taVNS