Social support moderates the link between chronic peer victimization in school and later cortisol secretion

Using a genetically informed design based on twins, this study tested the association between chronic peer victimization from ages 12 to 17 and later cortisol secretion at age 19 and the moderating effect of social support in this regard. These associations were examined while also considering the effects of genetic factors and concurrent victimization experiences at age 19. Participants (148 monozygotic [MZ] and 227 dizygotic [DZ] twin pairs; 56% girls) reported on their peer victimization and social support from the mother, father, and best friend from ages 12 through 17. At age 19, they reported on victimization in college, at work, and in romantic relationships and provided a hair sample for cortisol measurement. Growth mixture modeling identified three victimization trajectories: low (34%), moderate (55%), and high (11%). Biometric modeling showed that a high trajectory of peer victimization in adolescence predicted lower cortisol levels compared with a low trajectory, but only at very low levels of friends’ support. Parental support did not moderate this association and no sex moderation was found. These results highlight not only the potential disruptive influence of chronic peer victimization on hypothalamic-pituitary-adrenal (HPA) axis functioning but also the buffering role of friendship when facing such adverse social experiences.