RESUMEN
BACKGROUND: Previous research has suggested that children with attention-deficit/hyperactivity disorder (ADHD) symptoms commonly show emotion dysregulation difficulties. These difficulties may partly explain the strong tendency for internalizing problems such as anxiety and depression to co-occur with ADHD symptoms. However, no study has yet provided a longitudinal analysis of the within-person links between ADHD symptoms, emotion dysregulation, and internalizing problems necessary to examine this hypothesis from a developmental perspective. METHODS: We used data from the age 3, 5, and 7 waves of the large UK population-representative Millennium Cohort Study (n = 9,619, 4,885 males) and fit gender-stratified autoregressive latent trajectory models with structured residuals (ALT-SR) to disaggregate within- and between-person relations between ADHD symptom, emotion dysregulation, and internalizing problem symptoms. RESULTS: We found that emotion dysregulation significantly mediated the longitudinal within-person association between ADHD symptoms and internalizing problems. CONCLUSIONS: Results underline the promise of targeting emotion dysregulation as a means of preventing internalizing problems co-occurring with ADHD symptoms.