Serum cortisol and neuroticism for post-traumatic stress disorder over 2 years in patients with physical injuries.

Aim: This study aimed to explore the relationships between serum cortisol levels, personality traits, and the development of Post-Traumatic Stress Disorder (PTSD) over 2 years among individuals with physical injuries.

Methods: Participants were consecutively recruited from a trauma center and followed prospectively for 2 years. At baseline, serum cortisol levels were measured, and personality traits were categorized into five dimensions (Extraversion, Agreeableness, Conscientiousness, Neuroticism, and Openness), using the Big Five Inventory-10. The diagnosis of PTSD during follow-up (at 3, 6, 12, and 24 months post-injury) was determined using the Clinician-Administered PTSD Scale for DSM-5. Binary and multinomial logistic regression analyses were conducted to examine the interactions between cortisol levels, personality traits, and PTSD development.

Results: Among 923 patients analyzed, 112 (12.1%) were diagnosed with PTSD at some point during the study period, with prevalence rates decreasing from 8.8% at 3 months to 3.7% at 24 months post-injury. Direct associations between cortisol levels or personality traits and PTSD were not observed. However, a significant interaction between lower cortisol levels and higher Neuroticism in relation to PTSD risk was identified, especially during the early follow-up periods (3 to 6 months), but this association waned from the 12-month follow-up onward.

Conclusion: Our findings reveal Neuroticism-dependent associations between serum cortisol levels and PTSD development, exhibiting temporal variations. These results suggest that PTSD development may be influenced by a complex, time-sensitive interplay of biological and psychosocial factors, underscoring the importance of considering individual differences in stress reactivity and personality in PTSD research and treatment.