Co-occurrence of internalizing difficulties and aggression in early childhood and risk of mental health problems in middle childhood

The goal of this prospective longitudinal study was to explore whether co-occurrent internalizing difficulties and aggression in early childhood convey increased risk for later mental health problems in middle childhood. Participants were mothers from the Norwegian Mother, Father and Child Cohort Study (MoBa), who provided assessments of child internalizing difficulties and aggression at ages 3 years (n = 54,644; 26,750 girls) and 5 years (n = 38,177; 18,794 girls), as measures of child depressive, anxiety, conduct-related, and oppositional defiant (OD) symptoms at age 8 years. Using latent profile analyses (LPA) of internalizing difficulties and aggression, four profiles were identified: low-symptom/normative; primarily internalizing; primarily aggressive; and co-occurrent. Among the other results, the co-occurrent group exhibited the highest levels of depressive, anxiety, and oppositional defiant symptoms at 8 years. Most children (78%) remained stable in their profile between ages 3 and 5 years. Among the transition patterns that emerged, transitions were observed both from the normative to a risk profile and vice versa. Children who remained stable within the co-occurrent profile or who transitioned from the co-occurrent profile to one of the other two risk profiles also exhibited more depressive, anxiety, and OD symptoms at 8 years of age, when compared with children who transitioned from the co-occurrent to the normative profile. The heterogeneity between early manifestation of internalizing difficulties and aggression, and specific type of later mental health symptoms not only supports a shared etiology between internalizing and externalizing difficulties but also points toward the need for person-centered monitoring in early childhood with further implications for early identification of difficulties and preventive measures.