Higher Levels of Basal Serial CSF Cortisol in Combat Veterans With Posttraumatic Stress Disorder

OBJECTIVE: Results of basal peripheral cortisol measures in posttraumatic stress disorder (PTSD) have been variable. The authors' goal was to measure CSF cortisol concentrations, which more accurately reflect brain glucocorticoid exposure, in subjects with or without PTSD. METHOD: CSF was withdrawn from a subarachnoid catheter and plasma from a venous catheter, both indwelling, over a 6-hour interval to determine hourly plasma ACTH and cortisol concentrations and hourly CSF cortisol levels in eight well-characterized combat veterans with PTSD and eight matched healthy volunteers. RESULTS: Mean CSF cortisol concentrations were significantly higher in the subjects with PTSD (3.18 ng ml, SD=0.33) than in the normal volunteers (2.33 ng ml, SD=0.50), largely due to higher CSF cortisol concentration nadirs. No group differences were observed in either plasma ACTH or peripheral (plasma or urinary free) cortisol. CSF corticotropin-releasing hormone and CSF cortisol concentrations were positively and significantly correlated. CONCLUSIONS: Despite normal peripheral cortisol indexes in the veterans with PTSD, their CNS exposure to cortisol was greater than that of normal comparison subjects.