Post-traumatic stress disorder (PTSD) is a complex condition associated with changes in multiple neurobiological systems, including the autonomic nervous system and inflammatory pathways. Current treatments, primarily medications and trauma-focused psychotherapies, leave many patients without adequate symptom relief. Researchers have begun investigating whether non-invasive vagus nerve stimulation might influence the physiological systems involved in PTSD.

Of the two studies summarized below, one used transcutaneous auricular neurostimulation (tAN®), the platform developed by Spark Biomedical, which stimulates both the auricular branch of the vagus nerve and the auriculotemporal nerve. The other used transcutaneous cervical vagus nerve stimulation (tcVNS), which delivers stimulation through the neck rather than the ear. These are distinct stimulation methods. Both studies are presented here as part of the broader early-stage research on vagus nerve stimulation in trauma- and stressor-related conditions. Neither study evaluates any consumer wellness product.

Study 1: tAN® and PTSD Symptoms During Opioid Withdrawal

Tirado et al., 2022 — Bioelectronic Medicine

This prospective inpatient clinical trial investigated tAN® for managing opioid withdrawal syndrome (OWS). Thirty-one adults with active opioid physical dependence were enrolled. The study's primary purpose was to measure changes in opioid withdrawal symptoms, but the researchers also included exploratory measures of depression, PTSD symptoms, and overall quality of life. PTSD symptoms were measured using the PCL-5 (PTSD Checklist for DSM-5) at baseline and again after 5 days of tAN® therapy.

Participants received active tAN® up to 24 hours per day over the 5-day inpatient period. According to the authors, PCL-5 scores were significantly reduced from baseline to Day 5 (a 32.7% reduction, p = 0.0013). In the discussion, the researchers noted that approximately one-third of participants experienced a clinically meaningful reduction in PTSD symptoms. The authors describe these PTSD findings as exploratory and as suggesting tAN® may influence symptoms relevant to the underlying conditions that often co-occur with opioid use disorder, including depression, PTSD, and trauma.

Important context: this study was designed to evaluate opioid withdrawal, not PTSD specifically. The PTSD measurement was a single comparison from baseline to Day 5 without a sham control on that specific outcome. The participants were in active opioid withdrawal, a population with high rates of co-occurring mental health conditions. This study supported the FDA clearance of tAN® for opioid withdrawal syndrome.

Read the full study here.

Study 2: tcVNS in Patients with PTSD

Bremner et al., 2021 — Journal of Affective Disorders Reports

This pilot study investigated the effects of transcutaneous cervical vagus nerve stimulation (tcVNS) on PTSD symptoms and inflammatory responses to stress. The researchers had previously shown that tcVNS could blunt interleukin-6 (IL-6) responses to stress in PTSD patients. This study extended that work to examine symptom-level outcomes over a longer treatment period.

Participants received either active tcVNS or sham stimulation over a three-month period. The researchers measured PTSD symptoms and IL-6 inflammatory responses to stress. According to the authors, the three-month tcVNS treatment was associated with a greater reduction in PTSD symptoms compared to sham. They also reported differences in inflammatory response patterns between conditions, though the authors note that interpretation of these findings is complicated by baseline differences between groups.

The authors describe this as a pilot study with a small sample, intended to inform future larger trials. The study used a cervical (neck-based) stimulation approach distinct from the auricular (ear-based) stimulation used in tAN® and taVNS research. This work contributed to the FDA's later Breakthrough Device designation for a non-invasive vagus nerve stimulation device in PTSD, a regulatory pathway that supports continued investigation but is not equivalent to FDA approval or clearance.

Read the full study here.

Where the Research Stands

Research on non-invasive vagus nerve stimulation and PTSD symptoms is in an early phase. The two studies summarized here used different stimulation methods, different populations, and different study designs. Both are characterized by their authors as preliminary or exploratory.

The Tirado study suggests that tAN® may influence PTSD symptoms as one of several outcomes in a population with co-occurring opioid use disorder. The Bremner study suggests that tcVNS may influence PTSD symptoms in patients with PTSD. Larger randomized controlled trials specifically designed to evaluate these effects are needed before any clinical conclusions can be drawn.

As more research emerges, the picture of how different vagus nerve stimulation methods may interact with the systems involved in PTSD will continue to develop.