• Clinician Administered PTSD Scale (CAPS) [ Time Frame: Week 0,2,4,6,8,10 ] [ Designated as safety issue: No ]
• Clinical Global Impressions - Improvement (CGI-I) [ Time Frame: Week 0,2,4,6,8,10 ] [ Designated as safety issue: No ]

• Sheehan Disability Inventory (SDI) [ Time Frame: Week 0,4,6,10 ] [ Designated as safety issue: No ]
• Brief Symptom Inventory - 18 item (BSI-18) [ Time Frame: Week 0,2,4,6,8,10 ] [ Designated as safety issue: No ]

Developing novel and effective pharmacologic interventions for this post-traumatic stress disorder is important. The investigators propose to replicate findings of an earlier published pilot study using low dose hydrocortisone as a treatment for PTSD. In order to do so in a more meaningful way, the investigators will conduct a larger but similar randomized double-blind placebo-controlled, cross-over design treatment study examining the use of low dose hydrocortisone (or placebo) for 4 weeks in combat veterans suffering from PTSD.

The investigators hypothesize that, as described by Aerni et al. (2004), administration of daily hydrocortisone will lead to a reduction in PTSD symptom severity, but particularly for re-experiencing types (e.g., flashbacks, nightmares)of symptoms. The investigators also hope to examine potential predictors and moderators of treatment response based on subjects' clinical characteristics, as well as serum cortisol and ACTH levels.

• Drug: Hydrocortisone
• Drug: Placebo

• Aerni A, Traber R, Hock C, Roozendaal B, Schelling G, Papassotiropoulos A, Nitsch RM, Schnyder U, de Quervain DJ. Low-dose cortisol for symptoms of posttraumatic stress disorder. Am J Psychiatry. 2004 Aug;161(8):1488-90.
• Schelling G, Briegel J, Roozendaal B, Stoll C, Rothenhäusler HB, Kapfhammer HP. The effect of stress doses of hydrocortisone during septic shock on posttraumatic stress disorder in survivors. Biol Psychiatry. 2001 Dec 15;50(12):978-85.
• Schelling G, Kilger E, Roozendaal B, de Quervain DJ, Briegel J, Dagge A, Rothenhäusler HB, Krauseneck T, Nollert G, Kapfhammer HP. Stress doses of hydrocortisone, traumatic memories, and symptoms of posttraumatic stress disorder in patients after cardiac surgery: a randomized study. Biol Psychiatry. 2004 Mar 15;55(6):627-33.
• Olff M, Güzelcan Y, de Vries GJ, Assies J, Gersons BP. HPA- and HPT-axis alterations in chronic posttraumatic stress disorder. Psychoneuroendocrinology. 2006 Nov;31(10):1220-30. Epub 2006 Nov 1.

Inclusion Criteria:

• Male military veterans
• Between the ages of 18-65 years old
• Generally good medical health with no clinically significant abnormalities on physical examination, electrocardiogram, or laboratory findings
• Ability to provide informed consent and comply with requirements of study protocol
• No specific contraindications to hydrocortisone
• Clinically predominant DSM-IV diagnosis of PTSD
• Score of ≥ 40 on Clinician Administered PTSD Scale [CAPS]

Exclusion Criteria:

• History of moderate to severe traumatic brain injury, seizure or organic mental illness
• Lifetime history of schizophrenia, bipolar disorder, other psychotic disorder, or depression with a score of ≥ 16 on the 17-item Hamilton Depression Rating Scale (Hamilton, 1960), active suicidal ideation
• Unstable medical illness
• Subjects undergoing any formal psychotherapy within 3 months of enrollment
• Subjects that meet criteria for substance dependence during the last 6 months
• History of adverse reaction to corticosteroids.
• Concurrent use of other psychotropic medication (e.g. benzodiazepines, antipsychotics)