The goal of this clinical trial is to evaluate the safety and effectiveness of the gammaCore non-invasive vagus nerve stimulation (nVNS) device as an additional treatment for symptoms of post-traumatic stress disorder (PTSD) in adults.

The vagus nerve connects the brain with many organs and systems in the body and plays a role in regulating stress and emotional responses. The gammaCore device is a handheld, rechargeable medical device that delivers gentle electrical stimulation to the vagus nerve through the skin on the side of the neck. By stimulating this nerve, the device may help reduce PTSD symptoms.

gammaCore is cleared by the U.S. Food and Drug Administration (FDA) for the treatment and prevention of migraine and cluster headache. It has not yet been approved for the treatment of PTSD. This study is being conducted to better understand whether this type of stimulation may help improve PTSD symptoms and to evaluate its safety when used for this purpose.

The main questions this study aims to answer are:

• Is non-invasive vagus nerve stimulation safe for people with PTSD when used regularly at home?
• Does treatment with the gammaCore device improve PTSD symptom severity over time?

In this study, approximately 40 adults with PTSD will participate in an open-label pilot study.

Participants will first complete a 4-week baseline period in which their PTSD symptoms are monitored. This allows researchers to understand each participant's symptoms before starting the intervention.

Participants will then begin a 12-week treatment period using the gammaCore device at home. During this time, participants will apply the device to the side of the neck for short stimulation sessions each day as instructed by the study team.

Participants will attend six study visits, some conducted remotely and some in person. These visits include screening, training on how to use the device, and follow-up assessments. During the study, participants will complete questionnaires and clinician-administered assessments that measure PTSD symptoms and quality of life. Researchers will also monitor participants for any side effects or medical problems related to the device.

By collecting information on symptoms, safety, and device use, this study will help researchers understand whether non-invasive vagus nerve stimulation could become a useful treatment option for people living with PTSD.

Inclusion Criteria:

• PTSD diagnosis as determined by the Structured Clinical Interview for DSM-5 (SCID) interview for PTSD
• CAPS-5 score > or = 35
• Between the ages of 18 and 70 years
• Has PTSD symptoms and either is not taking PTSD medications or stable on PTSD medications for 3 months.
• Agrees to refrain from initiating or changing the type, dosage, or frequency of any prophylactic medications for indications other than PTSD that, in the opinion of the clinician may interfere with the study objectives (e.g., antidepressants, anticonvulsants, beta-adrenergic blockers, etc.)
• Agrees to use nVNS as instructed and follow all of the requirements of the study including Follow-up Visit requirements
• Able to provide written informed consent
• Must have a primary clinician (e.g. psychiatrist, therapist, psychologist, APRN, PA, etc.) responsible for psychiatric care before, during, and after the trial

Exclusion Criteria:

• Psychiatric or cognitive disorder and/or behavioral problems that, in the opinion of the clinician, may interfere with the study, such as symptoms of suicidal or homicidal risk.
• Evidence of a major medical or neurological illness on physical examination or as a result of laboratory studies (CBC, BUN, creatinine, blood sugar, electrolytes, liver and thyroid function tests, urinalysis, and EKG), such as cardiovascular, gastrointestinal, hepatic, renal, neurologic or other systemic illness; which in the opinion of the investigator or industry partner interferes with the study
• Cervical vagotomy or structural abnormality at the nVNS treatment site (e.g., lymphadenopathy, previous surgery, abnormal anatomy)
• Pain at the nVNS treatment site (e.g., dysesthesia, neuralgia, cervicalgia)
• Currently implanted with an electrical and/or neurostimulator device (e.g., cardiac pacemaker or defibrillator, vagal neurostimulator, deep brain stimulator, spinal stimulator, bone growth stimulator, cochlear implant, sphenopalatine ganglion stimulator, occipital nerve stimulator)
• Pregnant or thinking of becoming pregnant during the study period, or of childbearing years and unwilling to use an accepted form of birth control
• Belongs to a vulnerable population or has any condition such that his or her ability to provide informed consent, comply with the follow-up requirements, or provide self-assessments is compromised (e.g., homeless, developmentally disabled, prisoner)
• Patients with a stellate ganglion block (SGB)
• An employee of the Investigator or the clinical study site
• Recent (within 4 weeks) or concurrent use of a rapid-acting antidepressant agent (e.g., ketamine, esketamine, ECT) and/or other non-invasive stimulation therapy (e.g., TMS, transcranial focused ultrasound)