DIRECT AND INDIRECT EFFECTS FROM AGGRESSION TO INTERNALIZING SYMPTOMS: A GENETICALLY CONTROLLED STUDY

Behavioral difficulties in the early school years pose a risk to psychosocial functioning. The failure model suggests that peer rejection explains longitudinal associations between aggression and internalizing symptoms. The model postulates that aggression leads to increases in peer rejection, which, in turn, contributes to internalizing symptoms. This study tests pathways posited by the failure model, examining direct and indirect longitudinal effects. Direct effects models examined associations between reactive aggression and internalizing problems, reactive aggression and peer rejection, and peer rejection and internalizing symptoms. A mediation model examined the indirect effect of reactive aggression to internalizing symptoms, via peer rejection.
Because distinct components of the failure model are presumed to share genetic influences, removing potential genetic contributions is important when examining the environmental influences over developmental pathways posited by the model. To this end, longitudinal tests were conducted with traditional (non-genetically controlled) and MZ twin difference (genetically controlled) designs. The latter disentangled nonshared environment effects from those for genetic factors from environmental factors.