Gender differences in externalizing and internalizing problems across childhood and adolescence

Background: Childhood differences in externalizing and internalizing behavior problems have lasting implications for mental health. Identifying the factors that explain when and why children’s emotional and behavioral problems emerge is key to mitigating their long-term impact. One such clinically informative factor is gender. Here, we chart boys’ and girls’ developmental trajectories of externalizing and internalizing problems, as well as their prosocial behaviors, from early childhood through adolescence across three longitudinal cohort studies. Methods: Data were drawn from three longitudinal cohorts (total N = 43,826, including 22,032 boys and 21,794 girls): Twins Early Development Study (TEDS; N = 18,828), Millennium Cohort Study (MCS; N = 14,945), and Etude Longitudinale Française depuis l’Enfance (ELFE; N = 10,053). TEDS children were born in 1994-1996 in England and Wales; MCS children were born in 2000-2002 across the UK; and ELFE children were born in 2011 in France. Across cohorts, parents rated their children on the Strengths and Difficulties Questionnaire (SDQ from as early as age 2 years up to age 16 years. We fitted linear mixed-effects models. Results: Boys scored higher on externalizing problems and lower on prosocial behaviors than girls, with moderate effect sizes (average Cohen’s d ~.32). No significant gender differences emerged for internalizing behavior problems. In boys and girls, externalizing problems decreased as children grew older, while prosocial behaviors increased; both development trends were curvilinear. Results were remarkably consistent across cohorts.Conclusions: Gender differences in externalizing problems (boys > girls) were stable from early childhood through adolescence. Their effect sizes indicated that the gender gap in adult externalizing spectrum disorders may have developmental precursors in childhood. In contrast, gender differences in internalizing spectrum disorders are likely to emerge or widen after adolescence.