Longitudinal Relationships between Self-efficacy, Post-traumatic Distress and Salivary Cortisol among Motor Vehicle Accident Survivors

The present study tested if post-traumatic distress following a motor vehicle accident (MVA) and MVA-related self-efficacy beliefs were associated with diurnal salivary cortisol in the early post-traumatic period. Cortisol was collected upon awakening and at 1, 4 and 12 h after waking. Collection days were 1 week, 1 month and 3 months after MVA. A total of 30 participants provided their cortisol samples across all measurement points. Two methods for computing the area under the cortisol curve were used. Higher post-traumatic distress at 1 month predicted lower cortisol area under the curve (AUC) with respect to increase (AUC(I), reflecting changes in cortisol secretions during daytime) at 3 months. AUC with respect to ground (AUC(G), reflecting total cortisol release during daytime), measured at 1 month after trauma, predicted higher post-traumatic distress at 3 months. The results showed that self-efficacy at 1 week indirectly predicted 3-month AUCI through 1-month post-traumatic distress. These findings highlight the importance of self-efficacy and post-traumatic distress in explaining longitudinal diurnal patterns of cortisol secretion after trauma. Copyright (C) 2011 John Wiley & Sons, Ltd.