Abstract
Adverse and benevolent childhood experiences (ACEs and BCEs, respectively) are uniquely associated with posttraumatic stress disorder (PTSD) and complex PTSD (CPTSD); however, there is no systematic review on the mechanisms of these associations. This systematic review and meta-analysis aimed to synthesize studies considering psychological mediators of the associations between ACEs/BCEs and PTSD/CPTSD. Databases (PsychINFO, PubMed, PTSDpubs, PsycARTICLES, and Web of Science) were searched from inception to August 2025 for peer reviewed studies of adult populations examining psychological mediators of the associations between ACEs or BCEs and PTSD or CPTSD. A total of 63 studies involving 31,540 participants met the inclusion criteria. Mediators were grouped into six categories: cognitive beliefs and appraisals (n = 33), emotion regulation strategies (n = 40), interpersonal relationships (n = 7), spiritual and religious beliefs (n = 2), attachment style (n = 5), and dissociation symptoms (n = 9), with mostly small effect sizes. Subcategory meta-analysis revealed emotion regulation, β = .4, 95% CI [0.001, 0.78], and maladaptive coping strategies, β = .05, 95% CI [0.03, 0.07], significantly mediated the association between ACEs and PTSD. Risk of bias and quality of evidence were assessed. Overall, evidence was insufficient to determine how mediators function across pathways, and a paucity of literature is highlighted, considering BCEs and CPTSD.