Socioeconomic inequalities in children’s mental health are already evident by age five and persist throughout childhood and adolescence, according to analysis led by researchers from the University of Liverpool.
The study provides one of the most comprehensive examinations to date of how different types of mental health difficulties – internalising (e.g. anxiety, sadness) and externalising (e.g. impulsivity, defiance) – manifest across childhood and adolescence, and how these patterns are shaped by early life socioeconomic disadvantage.
Researchers analysed data from more than 15,000 children born around the year 2000 and tracked through to age 17, using parent-reported measures. The team, including academics from the University of Liverpool and the University of Glasgow, found that while different types of mental health difficulties vary by age and sex, the gap between more and less advantaged children remains strikingly stable across time.
Dr Yu Wei Chua, lead author and Research Associate in the Health Inequalities and Policy Research Group at the University of Liverpool, and NIHR Researcher at the Oxford Health Biomedical Research Centre said: “Our findings show that the mental health gap is already firmly in place by age five, regardless of whether we use income or maternal education to index socioeconomic disadvantage.”
Key findings include:
- Externalising difficulties (e.g. behavioural problems) remained fairly stable over time, with boys showing higher levels than girls.
- Internalising difficulties (e.g. anxiety and depression) increased with age, particularly among adolescent girls.
- Socioeconomic inequalities were present across all ages and both sexes, with larger gaps observed in externalising difficulties.
- These inequalities did not significantly change between ages 5 and 17, highlighting the enduring influence of early-life disadvantage.
Although developmental patterns and sex differences in mental health were evident, the persistence of inequality suggests that efforts to address disparities need to begin in the early years and continue throughout the school-age period.
Dr Yu Wei Chua continues: “This research confirms that we cannot wait until problems arise in adolescence to intervene. Mental health inequalities are already entrenched in early childhood. But there is another window of opportunity in adolescence, especially to prevent a further rise in internalising difficulties in adolescents facing disadvantage.”
The study authors call for a multifaceted, multi-system approach to reduce inequalities, including:
- Early interventions through investment in early childhood education and care, to better detect and support children showing early signs of difficulty.
- School-based mental health support during adolescence, particularly to address the rise in internalising difficulties among girls.
- Addressing wider social determinants, including child poverty, parental mental health, and parenting support.
Dr Anna Pearce, Senior Research Fellow (Public Health) at the University of Glasgow and the paper’s co-author concludes: “Reducing child poverty remains fundamental, but it’s equally critical to support families and children across multiple systems—health, education, and social care.”
“Now, we need more research on poverty reduction strategies and the role that families, services and communities play in tackling mental health inequalities.”
The researchers are funded by the National Institute for Health and Care Research (NIHR), the NIHR Oxford Health Biomedical Research Centre, the Medical Research Council, the Scottish Government Chief Scientist Office and Wellcome.
The study, ‘Socioeconomic inequalities in mental health difficulties over childhood: a longitudinal sex-stratified analysis using the UK Millennium Cohort Study’ was published in Social Science & Medicine (DOI: 10.1016/j.socscimed.2025.118159).