Series www.thelancet.com Vol 369 April 21, 2007 1391 Adolescent Health 4 Interventions to reduce harm associated with adolescent substance use J W Toumbourou, T Stockwell, C Neighbors, G A Marlatt, J Sturge, J Rehm Summary A major proportion of the disease burden and deaths for young people in developed nations is attributable to misuse of alcohol and illicit drugs. Patterns of substance use established in adolescence are quite stable and predict chronic patterns of use, mortality, and morbidity later in life. We integrated findings of systematic reviews to summarise evidence for interventions aimed at prevention and reduction of harms related to adolescent substance use. Evidence of efficacy was available for developmental prevention interventions that aim to prevent onset of harmful patterns in settings such as vulnerable families, schools, and communities, and universal strategies to reduce attractiveness of substance use. Regulatory interventions aim to increase perceived costs and reduce availability and accessibility of substances. Increasing price, restricting settings of use, and raising legal purchase age are effective in reducing use of alcohol and tobacco and related harms. Screening and brief intervention are efficacious, but efficacy of a range of treatment approaches has not been reliably established. Harm-reduction interventions are effective in young people involved in risky and injecting substance use. In many countries, overdoses of alcohol and other drugs compete with road crashes as leading causes of death in young people. 1 The substantial contribution of alcohol and other drugs to suicide, homicide, a range of injuries, poisoning, and the spread of infectious disease is also now well established. 2,3 Hazardous alcohol use alone has been estimated to cause 31·5% of all deaths in 15–29-year-old men in the developed world and 86% of the 3·6 million substance-related deaths of 15–29-year-old men and women worldwide (table 1). Psychoactive substance use occurs in all known societies, with heavy episodic or binge use being especially common among young people, 5–8 so that the risk of these adverse acute consequences can be seen as a function of societal context as well as individual susceptibility. In 2000, the use of alcohol and illicit drugs was estimated to contribute 9·8% of the total global burden of disease for people aged 15–29 years (table 2). This burden fell disproportionately on male individuals and people living in developed countries. In economically developed countries, 23·3% of the global burden of disease is contributed to by alcohol (18·5%) and illicit drugs (4·9%). No evidence exists of significant health benefits from moderate alcohol consumption for young adults to offset these adverse effects. 2,9 There are several social and legal con- sequences of substance use for young people, including work and travel restrictions as a consequence of a Lancet 2007; 369: 1391–401 Published Online March 27, 2007 DOI:10.1016/S0140- 6736(07)60369-9 See Comment page 1323 This is the fourth in a Series of six papers about adolescent health Centre for Adolescent Health, Murdoch Childrens Research Institute and School of Psychology, Deakin University, Victoria, Australia (Prof J W Toumbourou PhD); Centre for Addictions Research of British Colombia, University of Victoria, PO Box 1700 STN CSC Victoria, BC V8W 2Y2, Canada (Prof T Stockwell PhD, J Sturge MD); National Drug Research Institute, Curtin University, Perth, Australia (T Stockwell); Department of Psychiatry and Behavioral Sciences, School of Medicine, University of Washington, Seattle, USA (C Neighbors PhD, Prof G A Marlatt PhD); and Centre for Addictions and Mental Health, Toronto, Ontario, Canada (Prof J Rehm PhD) Correspondence to: Dr T Stockwell timstock@uvic.ca Search strategy We aimed to complete an integrative summary of current knowledge of the effectiveness of interventions designed to prevent and reduce the major harms associated with adolescent substance use. The co-authors, selected because of their expertise in specific areas of work in this area, supplemented recently completed comprehensive systematic reviews 53,57 using the PubMed, Psychlit, and Google scholar electronic databases, and keyword and text searches relevant to (adolescen*) and (alcohol or drug or substance and use or abuse) and (review) to locate additional systematic review papers published in the past 2 years. The conclusions of review papers were included where they met quality standards for systematic selection and methodological evaluation. 27, 28 Authors were asked to integrate review findings citing key evidence from well-done and influential empirical studies and noting implications for research and practice. A judgment of intervention efficacy required overall positive evidence from well-controlled outcome evaluations. Interventions were judged as effective where outcomes were maintained outside controlled research contexts in real-world service delivery conditions. 29 We used a broad definition of substance use, which included adolescent use of alcohol (ethanol) and tobacco, and non-medical use of prescription medications (including analgesics and sedatives) and illicit drugs including cannabis, heroin, cocaine, amphetamine- type substances, and hallucinogens. As relevant to substance use, adolescence was defined broadly to refer to the period before puberty (around age 10 years) through to the achievement of financial independence in emerging adulthood (around late 20s). 30 Literature relevant to harms, current substance use trends, and influences was overviewed to provide a context for intervention. We summarise current understanding of intervention opportunities and the conclusions of evaluation studies that have examined effects in modification of behaviour, reduction of harm, and savings in costs.