Neuroendocrine Risk for PTSD in Women Study looks at how a female hormone, called estradiol (E2), affects PTSD (Post-Traumatic Stress Disorder) symptoms. PTSD is a condition that can happen after someone goes through a frightening event. This study checks if different levels of E2 during a woman's menstrual cycle can make her more stressed. The study involves a special brain scan called an fMRI (functional magnetic resonance imaging) to see how the brain reacts to stress. There are three groups: women with PTSD, women exposed to trauma but without PTSD, and healthy women without trauma.

• Length: One full menstrual cycle using a tracking app, plus two MRI visits.
• Eligibility: African American women with a recent menstrual period and smartphone access.
• Exclusions: No hormonal birth control, pregnancy, smoking, or certain health conditions.

Participants will wear either an E2 or placebo patch and get their brains scanned twice. The goal is to understand if lower E2 makes women more prone to stress and help improve treatments for women with PTSD in the future.