We searched Project Cork bibliographies, PubMed Clinical Queries, Scopus, MEDLINE, MEDLINE-in-process, Embase, and PsycINFO for reviews that examined the epidemiology of substance use in young people and of associated health and social consequences published between Jan 1, 1990, and April 23, 2015. The appendix has the full list of search terms used, including “substance”, “adolescent”, and “health”. We also reviewed several major international sources of data and information about substance
SeriesThe increasing global health priority of substance use in young people
Introduction
Different cultures have used different substances to experience their intoxicating, euphoric, disinhibiting, or relaxing effects for thousands of years. Until industrialisation for production of beer and spirits, mostly in the mid to late 18th century in Europe, use of substances was constrained by their restricted and often seasonal availability. Nowadays, alcohol and tobacco are legally and readily available to adults in most countries. These are typically not legally available to young people below a specific age; however, the minimum ages and the extent to which they are enforced varies substantially across countries.1 Illicit drugs are defined as those drugs whose non-medical use has been prohibited by international drug control treaties because of the belief that they pose an unacceptable risk to the health of adult users.2, 3 These include plant-based substances (eg, heroin, cocaine, and cannabis) and synthetic substances, such as amphetamine-type stimulants and pharmaceutical opioids (eg, oxycodone, buprenorphine, and methadone). In this Series paper we focus on use of alcohol, tobacco, and illicit drugs (panel 1).
Substance use in young people (defined in this paper as aged 10–24 years; panel 1) has been the cause of increasing concern to parents, friends, communities, and policy makers. This concern underlines the fact that adolescence and early adulthood are key periods of transition. Substantial changes occur in the adolescent brain, including great cognitive and emotional development.8 Some have suggested that this period might, in itself, be a crucial time of susceptibility for the development of substance dependence.9 This period is also one in which key psychosocial transitions are typically made: completing education, transitioning to employment, forming sexual relationships, and transitioning to marriage and parenthood. Use of substances during these years is of concern to the extent that it might impair these transitions.10
Increasing attention has been given to substance use in young people across communities, countries, and global organisations. Young people were particularly noted in WHO's global strategy on alcohol,11 which was endorsed in 2010 by consensus at the 63rd session of the World Health Assembly (Geneva, May 17–21). WHO's Framework Convention on Tobacco Control,12 which has 168 signatories, noted that access to tobacco by young people was an issue. For both the alcohol and tobacco strategies, numerous policy levers are available to prevent and reduce use and harms, the strongest of which involves legislation to restrict the availability, use, and sales of these substances.1 However, there is concern that low-income and middle-income countries do not have the capacity to implement these13 in the face of promotional activities by the alcohol and tobacco industries.
In April, 2016, the UN General Assembly will convene a Special Session to review progress made against the 2009 Political Declaration and Plan of Action14 to address illicit drug use and harms globally. A particular focus will be upon young people. The policy levers available for illicit substances are much more restricted than for alcohol and tobacco since their non-medical use is illegal. UN Member States' efforts are often centred upon policing supply and consumption, whereas efforts to reduce demand for illicit substances typically focus upon prevention. There is less focus on harm reduction and treatment of illicit substance use and dependence in young people.
This is the first in a Series of three papers that discusses substance use in young people. We will present data about the epidemiology of substance use and health burden in young people; discuss key issues associated with substance use in young people, particularly the stage in the life course for patterns of substance use, persistence of use and progression to dependent use, and differences in use between sexes; identify several at-risk populations of young people; and discuss emerging trends in the availability, contexts of use, and resulting effects of substance use in young people.
Section snippets
When does substance use begin?
Adolescence is the peak period during which substance use first occurs. This finding is consistently reported in surveys of drug use in young people and young adults. Levels and frequency of use begin to increase in mid-adolescence and peak in very early adulthood, as reported in long-running US cohorts.15
The age of onset in prospective cohorts is similar in high-income countries.16 Figure 1 shows the age-of-onset curves for use of substance use in people using specific substances in the World
Regularity and quantity of use
We need to be clear about what we mean by substance use (panel 1). In adolescents, use of substances is typically sporadic, often experimental and opportunistic, with many young people taking advantage of opportunities to use substances and experiencing both the desired and the less positive effects. As adulthood approaches, an increasing number of young people have income from employment and increased independence in the ways in which they spend their time. Some young people begin to use drugs
Health burden
The Global Burden of Disease (GBD) studies estimated the health burden of injuries and diseases by combining years of life lost due to disability104 and years of life lost due to early mortality105 into a metric called disability-adjusted life-years (DALYs).106 WHO estimated that in 2004, the biggest contributors to health burden in 10–24 year olds were mental and substance use disorders (19% of DALYs), injuries (both unintentional and intentional; 12% of DALYs), and HIV, tuberculosis, and
Emerging trends that might affect substance use
Broadly speaking, two factors are changing the context of substance use in young people. The first concerns changes in availability of substances, reflecting marketing activities in some regions (eg, alcohol and tobacco in low-income and middle-income countries), increased sales of e-cigarettes in others, and the use of the internet to supply illicit substances. The second concerns changes in the regulatory environment, both for licit and illicit substances. As alcohol and tobacco become
Manufacture of amphetamine-type stimulants and new psychoactive substances, and changes in use of e-cigarettes and legal status of cannabis
Amphetamine-type stimulants are the second most widely used group of illicit drugs after cannabis.109 Added to these are an increasing number of new psychoactive substances (NPSs). NPSs mimic the stimulant effects of amphetamines, cannabinoids, and other drugs but are not under domestic or international control by the 1961 or 1972 UN Conventions on Narcotic Drugs.111 Of those experimenting with NPSs, young people are over-represented, although these substances are more typically used by
Concerns about the internet as a potential source of illicit substances
The internet has become an increasingly important part of everyday life for young people. It is used to exchange information about the types, effects, and ways to use substances.121 However, there is increasing concern that it might also be used to sell illicit substances. Substances can be sold on the surface web (indexed websites accessible via search engines, with illicit drugs sold as being not for human consumption), but an increasing amount of substances are being sold via the so-called
Conclusions
Our capacity to respond appropriately to substance use in adolescents is limited by the scarcity of evidence about the nature and extent of harms,10 extent of substance use, and shape of this problem. In this Series paper we focused on the nature of substance use. Without good coverage of high-quality data for the extent of substance use and the harms associated with it, policy responses will be poorly targeted and potentially might fail to address the most commonly used substances or the
Search strategy and selection criteria
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