The association between preschool behavioural problems and internalizing difficulties at age 10-12 years.

The aim was to study the association between preschool behavioural problems and emotional symptoms in 10- to 12-year-old children. The study was based on the Aarhus Birth cohort, Denmark, and included 1,336 children. Based on the parent-administered preschool behaviour questionnaire (PBQ), we identified three not mutually exclusive preschool behavioural categories: anxious-fearful (n = 146), hyperactive-distractible (n = 98), and hostile-aggressive (n = 170). Children without any known symptoms were considered well adjusted (n = 1,000). Borderline emotional (n = 105) and emotional difficulties (n = 136) were measured at age 10-12 years with the parent-administered strength and difficulties questionnaire (SDQ). Multinomial logistic regression analyses were used to adjust for potential confounding factors. We found that anxious-fearful behaviour and hostile-aggressive preschool behaviour were associated with twice the risk of school-age emotional difficulties. Comorbidity or confounding failed to explain these results. Hyperactive-distractible preschool behaviour was not associated with school-age emotional difficulties. Preschool anxious-fearful behaviour was associated with school-age emotional difficulties, suggesting internalizing symptom stability in some children from early childhood. Preschool hostile-aggressive behaviour was also associated with school-age emotional difficulties, which suggests transformation of one behavioural dimension into another through childhood, and the need to focus on both early internalizing difficulties and hostile-aggressive behaviour as risk factors for later internalizing difficulties.