Additional Study Information: The purpose of this study is to investigate the relationship between aging processes and PTSD, which may help identify novel therapeutic targets to promote healthier aging trajectories for PTSD patients. Chronic PTSD increases mortality risk from medical diseases, promotes aging-associated syndromes such as frailty, and is linked to faster cognitive decline in older adults. One strong possibility is that PTSD leads to these adverse health outcomes by accelerating biological aging in the brain and body. Participants will be asked to attend a total of 3 visits consisting of: an evaluation, an MRI, and a day of neuropsychological testing.To determine eligibility, participants will first complete a phone screen with a research staff member. After this, participants may be scheduled to complete an eligibility evaluation. To compensate for the time required for the eligibility evaluation, we offer $50 cash upon completion. Additionally, you will be paid $300 if you complete all procedures in this study, including the two additional study visits. Payment will take place in the form of a check.