Exploring the developmental impact of internalising problems on hyperactivity/inattention symptoms in adolescence: An analysis of two UK-based longitudinal studies

Abstract Hyperactivity/inattention symptoms and internalising problems such as anxiety and depression commonly co-occur. Research and clinical practice are often based on the premise of hyperactivity/inattention symptoms being causally precedent in this association; however, emerging longitudinal research has suggested potential reciprocal pathways, with internalising problems also exacerbating hyperactivity/inattention symptoms. In this study we therefore used Understanding Society and the Millennium Cohort Study : two large longitudinal UK samples to explore the reciprocal developmental relations between Hyperactivity/inattention symptoms and internalising problems in adolescence. The analytic sample for Understanding Society included n = 13,680 participants (n = 6844 male, n = 6825 female) aged 10–15, the majority whom were White (n = 9,370). The analytic sample for MCS included n = 13,566 participants aged 11–17 (participants (n = 6,486 male, n = 6,683 female), the majority of whom were white (n = 11,241). Using a random intercept cross-lagged panel model (RI-CLPM) and RI-CLPM with reciprocal contemporaneous effects, we found evidence that internalising problems exacerbate hyperactivity/inattention symptoms (βs = .10 to .19). Evidence for a negative effect of hyperactivity/inattention symptoms on later internalising problems was inconsistent. Results point to the importance of considering pathways that lead from internalising problems to hyperactivity/inattention over adolescent development.