 The pituitary is a gland located at the base of the brain which controls the hormones in the body, including the stress hormones. Research in other psychiatric disorders has found changes in the pituitary volume along with changes in the hormones. This has not been investigated yet in PTSD. Therefore, we propose in our study to measure pituitary volume in people with PTSD and look at the changes in the stress hormone pathway. Moreover, we will investigate whether other hormones are affected by PTSD. In this way, we can further our understanding of the the biology of PTSD and help develop new therapies which can intervene through the hormonal system. 