Cortisol Awakening Response Prospectively Predicts Peritraumatic and Acute Stress Reactions in Police Officers

Background: The hypothalamic-pituitary-adrenal axis is a major stress response system hypothesized to be involved in the pathogenesis of posttraumatic stress disorder (PTSD). However, few studies have prospectively examined the relationships among pre-exposure hypothalamic-pituitary-adrenal activity, acute stress reactions and PTSD. Methods: Two hundred ninety-six police recruits were assessed during academy training before critical incident exposure and provided salivary cortisol at first awakening and after 30 minutes. A measure of cortisol awakening response (CAR) was computed as the change in cortisol level from the first to the second collection. At 12, 24, and 36 months following the start of active police service, officers were assessed for peritraumatic distress, peritraumatic dissociation, acute stress disorder (ASD) symptoms, and PTSD symptoms to their self-identified worst duty-related critical incident. Mixed models for repeated measures were used to analyze the effects of CAR on the outcome variables pooled across the three follow-up assessments. Results: After controlling for time of awakening, first awakening cortisol levels, and cumulative critical incident stress exposure, CAR during academy training was associated with greater peritraumatic dissociation, beta = .14, z = 3.49, p < .0001, and greater ASD symptoms during police service assessed at 12, 24, and 36 months, beta = .09, Z = 2.03, p < .05, but not with peritraumatic distress, beta = .03, z = .81, p = .42, or PTSD symptoms, beta = -.004, z = -.09, p = .93. Conclusions: These findings suggest that greater cortisol response to awakening is a pre-exposure risk factor for peritraumatic dissociation and ASD symptoms during police service.