Cortisol Augmentation of Prolonged Exposure Therapy

Inclusion Criteria: * Veterans who experienced a criterion A trauma while deployed, and a current diagnosis of PTSD with a minimum of 6 months * Capable of understanding, reading and writing English Exclusion Criteria: * Incapable and/or unwilling to provide written informed consent prior to participation * Unwilling and/or unable to discontinue current psychotherapy * Regular use of psychotropic medication including antidepressants, benzodiazepines, lithium, mood stabilizers, over-the-counter supplements (melatonin, kava-kava, ephedra) * Regular use of oral or inhaled steroids * Significant illness (e.g., type I or II diabetes requiring the use of insulin, HIV, AIDS, seizure disorder, anemia, Lyme disease, etc.) * The veteran, the veteran's physician, or the study physician think that the veteran's clinical state necessitates the prompt initiation of pharmacotherapy or other treatment that would preclude involvement in the study * Morbid obesity (VMI \> 40) * Clinically significant laboratory abnormalities as determine during medical clearance procedures * For women, a positive pregnancy test * Heavy smoking (more than 2 packs a day) * Substance and/or alcohol abuse and/or dependence within the previous 6 months * Response of 3 or 4 on the suicidality items of the HDRS or an assessed serious suicide risk * Current psychosocial problems that might interfere with treatment compliance * A lifetime history of schizophrenia, schizoaffective disorder, bipolar disorder, obsessive compulsive disorder or PTSD due to a trauma not sustained in the combat theater