Co-rumination mediates contagion of internalizing symptoms within youths' friendships.

Peer contagion of internalizing symptoms was examined within youths' friendships over 6 months. Children (Grades 3 and 5) and adolescents (Grades 7 and 9) paired in 274 reciprocal same-sex friendship dyads completed measures of depressive and anxiety symptoms, co-rumination, and self-disclosure. Depression contagion was present for all youth, and anxiety contagion was found in the sample of girls and older boys. Although normative self-disclosure did not mediate the contagion effects, co-rumination mediated the depression contagion effect for adolescents and the anxiety contagion effect in the sample of girls and older boys. Implications for interventions with youth at risk for developing internalizing symptoms are discussed.