Drug addiction is a long-term problem caused by an uncontrollable compulsion to seek drugs. It is a serious and growing problem. This makes it important to reduce the number of young people first using drugs, and to prevent the transition from experimental use to addiction. Schools offer the most systematic and efficient way of reaching them.
School programmes are categorised into four main groups:
1. Knowledge-focused curricula(courses of study) give information about drugs, assuming that information alone will lead to changes in behaviour.
2. Social competence curricula are based on the belief that children learn drug use by modelling, imitation and reinforcement, influenced by the child's pro-drug cognitions (perceptions), attitudes and skills. These programmes use instruction, demonstration, rehearsal, feedback and reinforcement, etc. They teach generic self management personal and social skills, such as goal-setting, problem-solving and decision-making, as well as cognitive skills to resist media and interpersonal influences, to enhance self esteem, to cope with stress and anxiety, to increase assertiveness and to interact with others.
3. Social norms approaches use normative education methods and anti-drugs resistance skills training. These include correcting adolescents' overestimates of the drug use rates of adults and adolescents, recognising high-risk situations, increasing awareness of media, peer and family influences, and teaching and practising refusal skills.
4. Combined methods draw on knowledge-focused, social competence and social influence approaches together.
We reviewed the evidence about the effect of school-based prevention interventions on reducing the use and intention to use drugsand increasing knowledge about the harms of drugs in primary or secondary school pupils.
We found a total of 51 studies (73 reports) with 127,146 participants involved. Twenty-seven studies compared 28 programmes adopting a social competence approach versus usual curricula, eight studies compared a social influence approach versus usual curricula, seven studies compared a combined approach versus usual curricula, two studies compared a programme based on knowledge only versus usual curricula, four studies compared other approaches versus usual curricula, seven studies assessed 11 different comparisons. They were mainly delivered in sixth and seven grade pupils (12 to 13 years). Most of the trials were conducted in the USA. The interventions were mainly interactive and five of them lasted one school year, 18 more than one school year and 29 less than one school year. In all other cases the duration was not clearly specified. Follow-up ranged from immediately after the end of the intervention up to 10 years.
Programmes based on social competence were mostly represented and showed a similar tendency to reduce the use of substances and the intention to use, and to improve knowledge about drugs, compared to usual curricula, but the effects were seldom statistically significant. Programmes based on social influence showed weak effects that were rarely significant. Programmes based on a combination of social competence and social influence approaches seemed to have better results than the other categories, with effective results in preventing marijuana use at longer follow-up, and in preventing any drug use. Knowledge-based interventions showed no differences in outcomes, apart from knowledge, which was improved among participants involved in the programme.
Quality of the evidence
The quality of evidence was moderate for some outcomes and comparisons, and was high for others. Most of the studies did not report adequately the way in which the study was conducted. Moreover, many studies did not report their results in a way that allowed them to be combined in a statistical summary.
The evidence is current to September 2013.