Equal-Life applies the exposome approach, providing a framework to study the long-term effects of multiple exposures of children, including causes and mechanisms driving inequalities in health. Important is also how single exposures add up or interact and how this affects mental health and cognitive development. The relationship is often not direct but dependent on other factors, known as mediators. The figure symbolises the interaction between the exposome and the outcomes through mediators.
This framework is based on literature reviews and analyses carried out to understand how the environment affects children’s development. Key mediators are sleep, stress, self-regulation, and biomarkers. Equal-Life also developed a social exposome framework. Data from eleven cohorts and school studies (250,000) and four tailored studies was supplemented with new information on the indoor and outdoor, social, and the built and natural environment.
The in-depth studies address child's activities in different places; how classroom sound and acoustics affect cognitive development; the impact of school and home environments on children’s wellbeing and brain activity;
how sleep mediates the relationship between environmental exposures and mental health.
The association between exposures, mediators and key outcomes was analysed extensively. Blood samples were tested for biological indicators linked to mental health and environmental influences.
Equal-Life’s multidisciplinary team harvested the results of the different parts of the project, and integrated these in key findings and recommendations which are also included in the Equal-Life tools and Guidebook.
Key findings
Equal-Life innovated noise and traffic models with high granularity, validated a propagation model and explored noise indicators relevant for sleep, stress, and restoration. Cluster analysis identified distinct exposome clusters shaped by contextual socioeconomic and physical neighbourhood factors. Deprived neighbourhoods show a higher prevalence of maternal and children’s mental health problems. Social and physical neighbourhood indicators are highly correlated within clusters, highlighting the need to address causes of inequities. Geographic Information System (GIS) data on built and natural environments combined with new data on micro-scale population statistics provided insight in the reduction of complex datasets, context for guiding design and interpretation of results. Fifty-seven indicators were analysed (N=196,052) showing a strong urban - rural divide (objective #1).
Places where children grow up and how and where they spend time impact their development. Physical and social factors combined explain more about mental health than either alone and effects are often indirect. Family life, access to green and blue spaces, environmental quality, and neighbourhood design all matter, and differ by age, city, and country. Mental health problems and delays in cognitive development are more common in socially deprived areas, showing structural social inequalities.
Access to green space/playgrounds, at home and elsewhere, correlates with improved mental and cognitive outcomes. Proteomic and metabolomic profiling showed links to mental health risk markers, but no robust, cohort-shared biomarkers have been identified yet. Mid-adolescence exposures related to lifestyle, indoor environmental quality, natural environment, and family environment were associated with proteomic biomarkers of mental health. The first results are promising, but too premature to contemplate early screening of biomarkers for mental health. The evidence-base needs to be strengthened and future studies should consider ethical aspects and the risk of medicalisation of childhood (objective #2).
The Equal-Life Toolbox and Guidebook were fully integrated in the EHEN Network Toolbox page, ensuring alignment with project objectives, results and user needs. Implementation was reinforced through training sessions, facilitated and widely adopted by diverse user groups from 31 countries. The Toolbox and Guidebook will remain publicly accessible beyond the project’s duration (objective #4).
Key recommendations
The findings present numerous opportunities for intervention. Designing interventions based on the analyses is challenging due to limited evidence on early exposome and their impact on mental health and cognitive development. Furthermore, it is essential to consider both physical and social environmental exposures. Results highlight the need for holistic, multi-domain approaches in child health policy. Interventions should integrate equity considerations to avoid exacerbating existing social gradients in mental health. The exposome concept is still unfamiliar to stakeholders and translation of findings into actionable policy remains a challenge, requiring user-friendly tools and frameworks with focus on preventive action (objective #3).
