Saliva cortisol in posttraumatic stress disorder: a community epidemiologic study

Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, so it was expected that posttraumatic stress disorder (PTSD) would be associated with activation of this axis; however, studies have found both increased and decreased cortisol in PTSD. To address this question, we collected saliva cortisol at home in a subsample of a longitudinal epidemiologic sample.

Six hundred eighty-four persons randomly selected from the total sample of 913 were requested to collect saliva samples upon awakening and in the early evening. Of these, 538 responded with samples, 516 of whom met inclusion criteria. These were 68 exposed to trauma with lifetime PTSD, 265 exposed to trauma with no PTSD, and 183 never exposed to trauma.

In a comparison of these three groups, lifetime PTSD revealed elevated evening saliva cortisol compared with exposed/no PTSD. When lifetime comorbidity with major depressive disorder (MDD) was included in the analysis, only persons with comorbid PTSD and MDD showed this evening elevation in cortisol. Persons with PTSD alone (never MDD) showed normal saliva cortisol levels, as did subjects with lifetime MDD alone.

Neither exposure to trauma nor PTSD alone is associated with alterations in saliva cortisol; however, elevated cortisol is found in PTSD comorbid with lifetime MDD.