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 Method: CSF was withdrawn from a subarachnoid catheter and plasma from a venous catheter, both indwelling, over a 6-hour interval to determine hourly plasma ACTH and cortisol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.