Co-occurrence of internalizing difficulties and aggression in preschoolers and mental health outcomes in adolescence

Evidence on how co-occurrent internalizing difficulties (ID) and aggression in early childhood influence mental health in adolescence is rather limited. Moreover, despite known heterogeneity in symptoms and comorbidities, sex differences in the association between early childhood difficulties and adolescent mental health remain largely unexplored. We investigated these gaps with data from the prospective Norwegian Mother, Father and Child Cohort Study (MoBa). Mothers reported on child ID and aggression at age 5 ( n = 11,996; 6,459 girls). Adolescents reported on life satisfaction, prosocial skills, depression, anxiety and conduct disorder symptoms, psychopathy, and psychotic tendencies and psychotic-like experiences at age 14. At age 5, children were classified in one of four profiles based on ID and aggression, that is, low-symptom/normative; primarily internalizing; primarily aggressive; co-occurrent. Adolescents in all three risk profiles reported lower life satisfaction; those in the primarily aggressive profile reported lower prosocial skills. Children in the co-occurrent profile reported higher depressive, anxiety and psychosis-related difficulties in adolescence, whereas primarily aggressive children reported higher depressive, conduct-related and psychosis-related difficulties and psychopathy. Sex did not significantly moderate these associations. Co-occurring internalizing problems and aggression during preschool signal increased risk for lower mental well-being and higher mental ill-being in adolescence, but with no evidence of sex differences. Early identification and preventive interventions, especially targeting aggression and co-occurring problems, may contribute to reducing later risk, including developing psychosis.