External locus-of-control partially mediates the association between cumulative trauma exposure and posttraumatic stress symptoms among adolescents from diverse background.

Locus of control (LOC) is a modifiable mediator of symptoms of posttraumatic stress disorder (PTSD) among traumatized individuals and a potential target of intervention. Compared with studies involving adults, the potential mediation effect of LOC on PTSD symptoms among trauma-exposed children and adolescents is relatively under-explored. This study, therefore, assessed the mediation effects of LOC on the association between lifetime cumulative trauma and PTSD symptoms among a large cohort of adolescents from different cultural background. Cross-sectional study. LOC was determined using the Multi-Dimension Locus of Control Scale; Posttraumatic stress symptoms using the UCLA PTSD Reaction Index; and other significant negative life events using the Life Events Checklist. Among 3826 adolescents who completed the study, external LOC explained 24% of variance ( = .24; F = 619.01;  < .01) in PTSD symptoms and had significant indirect effect on the relationship between self-reported cumulative traumatic event exposure and PTSD symptoms (ß = .14; 95% BC CI [.10, .20]). Moderated mediation results showed significant potentiation of the moderation effects among older adolescents; boys; and those from more affluent families. The study further strengthened the hitherto limited evidence that external LOC partially mediate the relationship between cumulative trauma exposure and PTSD symptoms among adolescents.