The first aim of the present study is to elucidate the pathophysiology of PTSD through the examination of the roles of GR and MR in maintaining PTSD HPA axis dysregulation. The second aim is to compare CSF CRH levels across groups in an effort to extend previous findings and determine whether CRH levels in PTSD are higher than levels in trauma exposed healthy subjects. The present investigation will also evaluate the relationship between CRH levels in PTSD, MR/GR function, hippocampal volume and hippocampally-mediated cognitive tasks. Finally, we will examine the effects of long-term paroxetine treatment in PTSD on HPA axis function, hippocampal volume, and hippocampally-mediated cognitive tasks.