Adolescent mental health outcomes following early regulatory problems.

Early regulatory problems (RPs), including excessive crying, sleeping difficulties, and feeding issues in infancy, are associated with later mental health difficulties. However, existing studies used broad mental health outcomes and inconsistent outcome measures. They have also overlooked adolescence, which is a crucial and sensitive developmental period. Using harmonized RP classifications, measured from 6 to 36 months of age, and item-level harmonized mental health dimensions, we examined emotional, social, hyperactivity / inattention, and conduct problems at ages 10, 14, and 18 years in two population-based cohorts (ALSPAC, N = 3870; Generation R, N = 1798). Longitudinal mixed models showed RP-related differences across all mental health dimensions. Specifically, children with multiple (two or more at one timepoint) or multiple-persistent (two or more RPs present at three or more timepoints in the first 36 months) RPs had consistently higher emotional, social, attention, and conduct problems, compared with participants without RPs. These differences remained stable across adolescence, with no evidence of RP-by-assessment wave interactions and were comparable for both sexes. Our cross-cohort findings support early RPs as early indicators of later mental health vulnerability. They additionally show that these associations can be identified reliably using harmonized exposure and outcome constructs across cohorts. Screening for these behaviors in routine pediatric care offers a practical method to identify at-risk children and guide early preventive interventions.