PTSD is one of the most universal and severe psychiatric disorders whose incidence continues to rise due to the common exposure to severe trauma in the United States and worldwide. After trauma, a proportion of individuals maintains high symptoms of PTSD and depression, which can persist for years. The early weeks following trauma present a unique opportunity to deliver early interventions that can prevent chronic PTSD and depression from occurring, and the researchers propose a brain-based intervention that will reduce reactivity to threat, an early risk mechanism for chronic PTSD. This study is being done to learn more about whether brain stimulation in the weeks after a trauma can change brain activity that is linked to Post-Traumatic Stress Disorder (PTSD).

After experiencing a traumatic event, there is a risk of developing Post-Traumatic Stress Disorder, which can disrupt everyday life and functioning. It is now well-recognized that many individuals experience initial psychological symptoms acutely following a traumatic event, but many recover naturally within the first 3 months post-trauma. However, about 20% of individuals continue to maintain high levels of debilitating symptoms that can persist for years following the trauma in the absence of treatment. Initial hyperarousal is a predictor of subsequent re-experiencing and avoidance symptoms. Such chronic symptoms present the greatest burden to individuals, associated with increasingly ingrained behavioral responses such as avoidance, decreasing quality of life, and the physiological consequences of chronic allostatic load, including cardiovascular and metabolic disorders. The burden to society is similarly tremendous, and annual costs associated with chronic post-trauma psychopathology are estimated to exceed $230 billion.

Interventions in the early post-trauma period could therefore provide an immense benefit to society by enhancing mechanisms that lead to recovery and resilience, thereby reducing chronic trauma-related psychopathology. This study is being done to test Transcranial Magnetic Stimulation (TMS) for early intervention for Post-Traumatic Stress Disorder. Researchers will test TMS in the weeks following a psychological trauma among individuals experiencing symptoms associated with acute stress. This usage of TMS is experimental. The study is being done to learn more about whether brain stimulation in the weeks after a trauma can change brain activity that is linked to Post-Traumatic Stress Disorder.

Inclusion Criteria:

• Men and women 18-65 years of age. (Assessed via self-reported and medical record-based Date of Birth)
• Trauma exposed within the last 2 weeks (Endorsement of having experienced an event that could have caused death, serious injury, or sexual violence)
• High initial symptoms of PTSD related to the index trauma - PCL-5 >30 AND meeting for all four DSM-5 clusters.
• Low symptoms of PTSD related to a previous lifetime trauma - PCL-5<31AND does not meet for all four DSM-5 clusters.
• Participants may be on psychotropic medication, including antidepressants, antipsychotics, benzodiazepines and anticonvulsants, but the dosage of the medication must be stable for at least 6 weeks and not change during the course of the study (Assessed via self-report during the screening phone call).
• Capable and willing to provide informed consent.

Exclusion Criteria:

• Having active suicidal intent or plan, or in the clinician's opinion, is likely to attempt suicide within the next six months. (Assessed via the Patient Health Questionnaire-9 (PHQ-9) during the screening phone call)
• Lifetime diagnosis of psychotic disorder or bipolar disorder per psychiatric screener. (Assessed via self-report during the screening phone call)
• Diagnosed with the following conditions: a neurological disorder, including a history of seizures, cerebrovascular disease, primary or secondary tumors in the central nervous system (CNS), stroke, cerebral aneurysm or movement disorder or any lifetime history of loss of consciousness for more than 5 minutes due to head injury (Assessed via self-report during the screening phone call)
• History of cranial surgery, metallic particles in the eye or head (exclusive of mouth), implanted cardiac pacemaker or any intracardiac lines, implanted neurostimulators, intra-cranial implants (e.g., aneurysm clips, shunts, stimulators, cochlear implants, or electrodes), or implanted medical pumps. (Assessed via self-report during the screening phone call)
• For women, being pregnant. (Assessed via self-report during the screening phone call, the medical record, and cycling females will undergo a pregnancy test at TMS Day 1)

The research team will share Individual Participant data that has been deidentified with the National Institute of Mental Health (NIMH) Data Archive (DA) as per the terms of the grant

Data will become available after the study and will follow the standard NDA access rules

Each participant will receive both the sham TMS and the true TMS. Participants will not be updated on which intervention they receive until the end of Day 2.