Background: Results on the association between posttraumatic stress symptoms (PTSS) and posttraumatic growth (PTG) are inconsistent, and there may be unknown factors mediating or moderating this relationship. Identifying these factors could help in developing an intervention strategy for promoting PTG. However, few studies have examined relationships among PTSS, resilience, and PTG concurrently, and no study has investigated the effect of childhood trauma on these relationships in adulthood.

Objective: The aim of this study was to examine the moderated mediating effect of childhood trauma on resilience and its associations with PTSS and PTG in adult victims of traumatic accidents or crimes. We hypothesized that resilience would mediate relationships between PTSS and PTG and that its mediating effects would differ depending on childhood trauma.

Methods: We included adult victims of accidents or crimes referred to a university hospital or specialized support centre (n = 143). PTSS, resilience, childhood trauma, and PTG were measured with the following questionnaires: PTSD Checklist for DSM-5, Connor-Davidson Resilience Scale, Adverse Childhood Experiences Questionnaire, and the Short Form of the Posttraumatic Growth Inventory, respectively.

Results: The effect of PTSS on PTG was found to be fully mediated by resilience, and this mediating effect was moderated according to childhood trauma: the more childhood traumatic experiences, the greater the mediating effect of resilience was between PTSS and PTG. The effect of resilience on PTG was highest in the high childhood trauma group.

Conclusion: Therapists treating individuals with psychological trauma should attempt to identify a history of childhood trauma and to evaluate resilience. Therapeutic approaches tailored according thereto may improve PTG among individuals with PTSS symptoms, especially those with high levels of childhood trauma.