Stress-related thinking predicts the cortisol awakening response and somatic symptoms in healthy adults

Objective: Perseverative cognition (i.e., worry, stress-related thinking) may prolong stress-related physiological activation. However, its role within the context of the written emotional disclosure paradigm has not been examined. This study explored: (1) the effects of stress-related thinking on the cortisol awakening response and upper respiratory infection symptoms and; (2) the efficacy of two expressive writing interventions on these health outcomes.

Methods: Participants were randomly assigned to write about their most stressful life experience (using the Guided Disclosure Protocol; n=39) or positive life experiences (n=42) or plans for the day (n=41) for 20 min on 3 consecutive days. Participants reported the extent to which they thought about their assigned writing topic during the study and in the past (event-related thought). Cortisol was measured at 0, 15, 30 and 45 min after awakening on 2 consecutive days at baseline and 4 weeks post-intervention. Upper respiratory infection (URI) symptoms were assessed at baseline, at 4 weeks and at 6 months.

Results: Results showed that the writing interventions had no beneficial effects on any of the outcome measures. However, a significant interaction was found between event-related thought and condition on the cortisol awakening response at 1 month follow-up and URI symptoms at 6 months. Among participants who wrote about stressful/traumatic events, higher stress-related thinking during the study predicted increased cortisol levels and URI symptoms compared to participants who reported low stress-related thinking.

Discussion: These findings are broadly consistent with Brosschot et al.'s (2006) perseverative cognition hypothesis and highlight the importance of ruminative thinking in understanding stress-health processes.