Despite some regional differences and a concentration of deaths in low-income and middle-income countries, there is commonality in the causes of adolescent deaths worldwide.1 The causes of adolescent death include communicable diseases (HIV/AIDS, tuberculosis, and lower respiratory-tract infection) and non-communicable diseases related to problem behaviours (motor vehicle fatalities, violence, self-harm, alcohol, tobacco, and other drugs, and risky sex leading to early or unintended pregnancy). Further, adolescence, partitioned into early (11–13 years), middle (14–18 years), and late (19–24 years) by the American Academy of Child and Adolescent Psychiatry,2 is a common period for the onset of symptoms and behaviours that lead to disorders in adulthood. For some disorders (eg, alcohol misuse and dependence, antisocial personality disorder), greater than 50% of first diagnoses across the life course are by age 25 years.3 Preventing adolescent problem behaviours might reduce the burden of morbidity in adolescence and adulthood.
Primary approaches to ameliorate these behaviour problems are health promotion, prevention, and treatment.3 At the turn of the 20th century in high-income countries, adolescence became a distinct time of life because of industrialisation, advances in medicine, improved nutrition, and public health, which increased the need for an educated workforce and led to universal education through the second decade of life.4 This extended period of dependence coincided with a rise in adolescent problem behaviours. Programmes designed to prevent these problem behaviours were first developed in the late 1960s in high-income countries, although few of these interventions were effective.5, 6, 7 In response to the disappointing results, prevention programme developers aligned with the science of behaviour development that discovered predictors. A second generation of prevention efforts sought to use this information to design programmes to address these predictors of specific problem behaviours, which was more successful.8, 9 These prevention interventions focusing on single problems came under criticism, and there was a movement towards considering the co-occurrence of problem behaviours within the adolescent and understanding the overlap in predictors across many behaviours.10 Others—ie, prevention practitioners, policy makers, and prevention scientists—advocated for more focus on factors that promote positive youth development, in addition to the focus on reducing factors that predict problems.11 They called for understanding the developmental processes involved in these disorders, including structural, intermediate, and individual risk and protective factors. Such concerns helped expand the design of prevention programmes to include components aimed at health promotion.3, 12 Over the past 30 years, several controlled trials have shown that preventive and promotive policies and programmes (called preventive interventions hereafter) can be efficacious and cost effective at reducing adolescent problem behaviour and improving health.13
Key messages
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Behaviour problems are important causes of adolescent morbidity and mortality
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There is sufficient evidence from controlled trials that carefully designed preventive interventions can improve adolescent health
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Effective adolescent health programmes should include a combination of preventive policies and programmes before and during the second decade of life
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A programme of public education is needed to ensure that policy makers, practitioners, scientists, and the general public are made aware of the health and social benefits and cost savings from evidence-based preventive interventions
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Research is needed on how to most effectively take such evidence-based prevention interventions to scale, including research on how to build community capacity, identify local need, match need to efficacious prevention interventions, support and sustain these interventions, and learn what adaptations might be needed for programmes designed in high-income countries to be effective in low-income and middle-income countres
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An international agency such as WHO, UNICEF, or The World Bank should be encouraged to convene a guideline development group to identify broad behavioural health risks confronting adolescents, recommend preventive policies and programmes that have evidence of reducing these risks and promoting adolescent health, and advise on actions that countries should institute to take up and sustain a national programme to promote adolescent health
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Databases should be developed, including a database of community surveys that comprehensively measure structural and intermediate determinants and health and behaviour problems, and a database of efficacious preventive policies and programmes across behaviour problems and health outcomes, the structural and intermediate determinants they address, and their target populations
Prevention science has had a different history in low-income and middle-income countries. In these countries, economic conditions have somewhat delayed the recognition of adolescence as a distinct life stage, although as these countries develop economically, with population shifts to urban centres, there is a growing recognition of adolescence.14 The research base that was developed in high-income countries has recently begun to be applied to low-income and middle-income countries through translation of existing approaches and developing and testing new preventive interventions in these lower-income contexts.
Treatment of adolescent behaviour problems remains the most common approach worldwide.15 Ultimately, some combination of treatment and prevention programmes would be ideal, but how to achieve this vision is somewhat uncertain.16 Investigators suggest that reducing a small amount of risk in the general (and proportionally larger) population might be epidemiologically more beneficial than reducing larger amounts of risk in the smaller, high-risk, segment of society.17, 18 Although evidence-based treatments are important, we advocate applying the growing research base for prevention science worldwide to substantially reduce morbidity and mortality.19
We provide an overview of the research base for prevention science and illustrative evidence of the efficacy of various preventive interventions. We surveyed broad outcomes, including obesity, violence, mental health, substance misuse, traffic crashes, pregnancy, and sexually transmitted infections, by assessing recent reviews and doing targeted searches of prevention controlled trials. We take a purposive approach, and have chosen to illustrate what works in prevention and health promotion, and refer to other more comprehensive and systematic reviews for other efficacious and non-efficacious interventions. In our opinion, the preventive interventions we have selected provide a broader overview of what is possible in preventing adolescent problems than comprehensive reviews of prevention programmes of a certain type or targeting a single problem behaviour.
We selected the programmes and policies identified in this report because they were tested in randomised or quasi-experimental trials, had a sustained and statistically significant effect on problem behaviours during adolescence at least 1 year after intervention, operate at different points in development during childhood and adolescence, and address accumulation of risk20 as well as adolescent risk onset.21 We chose these examples to provide some diversity in worldwide context, although most testing, particularly the long-term investigation of outcomes, has been done in high-income countries.
