Cross-cohort change in parent-reported emotional problem

Background Over the past three decades, the prevalence of adolescent emotional problems (ie, anxiety and depression) has risen. Although the onset and developmental course of emotional symptoms shows high variability, no study has directly tested secular differences across development. Our aim was to investigate whether and how developmental trajectories of emotional problems have changed across generations.Methods We used data from two UK prospective cohorts assessed 10 years apart: the Avon Longitudinal Study of Parents and Children (ALSPAC) including individuals born in 1991-92, and the Millennium Cohort Study (MCS) with individuals born in 2000-02. Our outcome was emotional problems, assessed using the parent-rated emotional subscale of the Strengths and Difficulties Questionnaire (SDQ-E) at approximate ages 4, 7, 8, 10, 11, 13, and 17 years in ALSPAC and ages 3, 5, 7, 11, 14, and 17 years in MCS. Participants were included if the SDQ-E was completed at least once in childhood and at least once in adolescence. Trajectories were generated using multilevel growth curve models using the repeated assessments of the SDQ-E in children aged 3-17 years.Findings Data were available for 19 418 participants (7012 from ALSPAC and 12 406 from the MCS), of whom 9678 (49 & BULL;8%) were female and 9740 (50 & BULL;2%) were male, and 17 572 (90 & BULL;5%) had White mothers. Individuals born between 2000 and 2002 had higher emotional problem scores from around 9 years (intercept statistic & beta; 1 & BULL;75, 95% CI 1 & BULL;71-1 & BULL;79) than did individuals born in 1991-92 (1 & BULL;55, 1 & BULL;51-1 & BULL;59). The later cohort had an earlier onset of problems than the earlier cohort, and sustained higher average trajectories from around 11 years, with female adolescents showing the steepest trajectories of emotional problems. Differences between cohorts peaked overall at age 14 years. Interpretation Our comparison of two cohorts of young people provides evidence that compared with a cohort assessed 10 years prior, emotional problems emerge earlier in development in the more recent cohort, and these are especially pronounced for females during mid-adolescence. Such findings have implications for public health planning and service provision.