Health anxiety moderates the association between morning cortisol and earlier-onset posttraumatic stress disorder: A 2-year injury cohort study.

Abstract

This study investigated whether baseline morning serum cortisol predicts the timing of PTSD onset following injury and determined whether this association is moderated by health anxiety. In a prospective injury cohort (N = 895), morning serum cortisol was measured and health anxiety was assessed using the Illness Attitude Scales (IAS) at baseline. PTSD was diagnosed with the Clinician-Administered PTSD Scale (CAPS-5) during follow-ups at 3, 6, 12, and 24 months. Earlier-onset PTSD was defined as onset within the first 6 months post-injury; delayed-onset PTSD was defined as onset after 6 months. Multivariable models examined the individual and interactive associations of cortisol and health anxiety with earlier- and delayed-onset PTSD, with both variables modeled continuously, adjusting for relevant demographic and clinical covariates. Spearman correlation tested the cortisol-IAS association. In separate adjusted models, neither baseline cortisol nor health anxiety was significantly associated with earlier- or delayed-onset PTSD. However, health anxiety significantly moderated the association between cortisol and earlier-onset PTSD: the association between lower cortisol and PTSD risk became stronger as health anxiety increased (OR=1.42, 95% CI 1.12-1.79, P = 0.004). No comparable interaction was observed for delayed-onset PTSD (OR=1.01, 95% CI 0.70-1.45, P = 0.966). Cortisol and IAS showed a significant negative correlation (Spearman ρ=-0.099, P = 0.003). The association between lower morning cortisol and earlier-onset PTSD became stronger with increasing health anxiety, highlighting a potential bio-cognitive interaction between HPA-axis regulation and health-related threat appraisal and suggesting potential value in integrating neuroendocrine and health-anxiety measures for future risk stratification.