Trends in mental health and behavioural outcomes in UK 10-15 year olds from 2009 to 2023

BackgroundGrowing concern about young people’s mental health contrasts with reported declines in risk and antisocial behaviours. Providing up-to-date information on multiple outcomes and understanding subgroups most affected can clarify potential mechanisms and inform interventions. This study provides an updated analysis of trends in mental health and behavioural outcomes among young adolescents in the UK.MethodsWe used data from 15,911 adolescents (aged 10–15 years) participating in the UK Household Longitudinal Study between 2009 and 2023. Trends were examined in mental health (emotional, hyperactivity, conduct problems), health behaviours (diet, physical activity), social media, parental relationships (frequency of arguments, discussed things that matter), risk behaviours (staying out after 9pm, smoking/vaping/alcohol use), and antisocial behaviours (shoplifting, vandalism, physical violence). Weighted logistic regression modelled yearly mental health time trends and changes in behavioural variables between earliest and latest data collection waves. We examined whether trends differed by sociodemographic variables by testing interaction terms.ResultsBetween 2009 and 2022, emotional problems more than doubled from 11.7% (95% CI: 10.7–12.7%) to 26.6% (95% CI: 24.4–28.9%), with the largest increases among 14–15-year-olds, girls, and white British adolescents. Hyperactivity remained stable until 2018 (17.1%, 95% CI: 16.3–18.0%), followed by an increase to 25.8% (95% CI: 23.7–27.8%) by 2022, mostly among girls. Social media use rose markedly, alongside increased fast-food consumption and declining physical activity. Positive trends included improved parental relationships and reductions in risk behaviours and conduct problems. Peer problems increased significantly, particularly for girls.DiscussionThis longitudinal, nationally representative sample shows sharply rising emotional problems, recent increases in hyperactivity symptoms, and declines in risk behaviours and conduct problems. These divergent patterns, and worse outcomes for girls and white British adolescents, may reflect distinct mechanisms, resilience, or measurement interpretation. Further research is needed to clarify underlying pathways and inform targeted interventions.