Table 1 Conceptual framework for NCDs among adolescents

The evidence-based conceptual framework (Fig. 1) represents a comprehensive, integrated and novel approach to understanding the complex pathways through which structural, community, school, family, peer, and individual risk and protective factors contribute to the global burden of NCDs among adolescents and in later adulthood.

Key definitions

Social Determinants of Health: Conditions in which people are born, grow, develop, live, work and age. This includes the social, political, economic, environmental and cultural systems and forces that influence and shape the health and wellbeing of individuals.

Macro, Societal & Political: Fundamental global and national social, economic, and political structures that shape inequalities in society, health and individual development. Macro trends include factors such as migration, conflict, environmental conditions, global economic development, technology and innovation. Societal and political determinants also represent underlying factors that substantially impact health, including national wealth, policies and laws, infrastructure, population density, governance, and culture.

Community & School: Circumstances of daily life where adolescents live, work and learn, including youth and women’s empowerment, quality and access to health services, education, transportation, access to health services and employment opportunities and conditions.

Family & Peer Factors: The primary protective and enabling structures that shape the health and development of young people. Relationships, connectedness, and the behaviours of family (e.g. parents, guardians, caretakers and siblings) and peers significantly influence the behaviour and health of adolescents.

Individual Factors: Individual developmental milestones and social role transitions, including sexual and reproductive health, early marriage, age of puberty, education and employment. Behavioural, biological, metabolic, nutritional, environmental and occupational factors that are protective or risk factors for individual adolescent health.

Macro, societal and political factors, including climate change and natural disasters, conflict, national wealth and health spending, infrastructure and urbanization, and governance represent critical overarching influences that shape the development and health of adolescents globally. These factors underlie and influence community and school factors, for example urbanization can improve young people’s access to education and health services, however may also increase young people’s risk for NCD-related risk factors, including mental health issues and obesity and physical inactivity [12].

Community and school level determinants play a substantial role in determining the current and future health of adolescents. Income inequality is associated with overall health outcomes, including mortality rates [9, 13] Inequalities in socioeconomic status also represent risks for NCDs including, increased physical inactivity, high BMI, poor psychological and physical well-being, high rates of substance use, bullying, and other poor behavioural and health outcomes [31, 32]. Access to education and educational attainment represent critical protective factors for health across the life-course. Better-educated individuals live longer and healthier lives globally, with lower mortality, and improved self-reported health outcomes [22, 33]. Diverse adolescent health outcomes and behaviours, including sexual and reproductive health, child marriage, mental health and self-harm [34] and obesity [33], are all positively influenced by increased educational attainment, particularly completion of secondary education. In addition, education significantly shapes the health of future generations, empowers youth and women, and narrows inequalities in status and health [35]. Availability and accessibility of health services represents a key approach to addressing and managing chronic health conditions and NCDs [36]. Youth unemployment and low-quality, unsafe, employment opportunities have been identified to significantly impact adolescents’ well-being, job satisfaction and health [37], including association with poor mental health, suicide and violence [22].

Family and peer connectedness, modeling of behaviours, and relationships represent significant protective or risk factors for adolescent health behaviours and outcomes, including smoking, violence, suicidal thoughts and behaviours, sexual and reproductive health, and overall healthy development [2, 36]. Connectedness and attitudes towards school have been associated with substance use, including drug, alcohol and tobacco [36]. Behaviours and risks vary across the life-course, and impact children and adolescents’ growth, development and risk for NCDs. Adolescence represents a time of significant biological, developmental and social role changes and transitions, including puberty, sexual and reproductive health, education, marriage, and employment. Furthermore, the initiation of behaviours such as tobacco use, poor diet, physical inactivity, and consumption of alcohol during childhood and adolescence contributes to the burden of disease during this time period, and substantially increases the risks for NCDs in later life. Mitigating and protective factors during adolescence include female empowerment and the empowerment of young people [35, 36]. The improved status of women in society (e.g. education, employment, increased age of marriage, etc.), has been associated with improved health outcomes for children and adolescents, while increased empowerment, education and employment of young people, are related to improved mental and physical health outcomes [22, 33, 34, 36]. The risk of developing NCDs increases across the life-course from childhood into adulthood [5], including increased risk of asthma, cardiovascular disease, diabetes, mental and substance use disorders (e.g. drug use disorders, major depressive disorder, etc.), musculoskeletal disorders, cancer, neurological disorders and other NCDs. Peer, family, community, national and broader global social determinants represent complex and interrelated factors that influence and shape individual behaviours and risks contributing to increased burden of NCDs. A supportive and enabling environment to develop and implement policies and interventions targeting structural, community, school, individual and crosscutting levels, represent a critical approach to improving adolescents’ health and development, and to addressing health behaviours and causes of NCDs (Appendix 7).