Elsevier

Addictive Behaviors

Volume 27, Issue 6, November–December 2002, Pages 1009-1023
Addictive Behaviors

Effective ingredients of school-based drug prevention programs: A systematic review

https://doi.org/10.1016/S0306-4603(02)00295-2Get rights and content

Abstract

Drug prevention in schools is a top priority in most Western countries and several well-designed studies have shown that prevention programs have the potential of reducing drug use in adolescents. However, most prevention programs are not effective and there are no general criteria available for deciding which program is effective and which is not. In this systematic review of the literature, the current scientific knowledge about which characteristics determine the effectiveness of drug prevention programs is examined. Three types of studies are reviewed: meta-analyses (3 studies were included), studies examining mediating variables of interventions (6 studies), and studies directly comparing prevention programs with or without specific characteristics (4 studies on boosters, 12 on peer- versus adult-led programs, and 5 on adding community interventions to school programs). Seven evidence-based quality criteria were formulated: the effects of a program should have been proven; interactive delivery methods are superior; the “social influence model” is the best we have; focus on norms, commitment not to use, and intentions not to use; adding community interventions increases effects; the use of peer leaders is better; and adding life skills to programs may strengthen effects.

Introduction

Several well-designed studies have shown that school-based drug prevention programs have the potential to reduce drug use in adolescents (Tobler et al., 2000). However, this research has also demonstrated that most drug prevention programs are not effective (White & Pitts, 1998). And, although a growing number of studies are examining which characteristics determine whether a prevention program is effective or not, the precise ingredients of effective prevention are not yet known.

At the same time, drug prevention in schools is a top priority in most Western countries. Drug abuse prevention has been made part of the educational curriculum for all youngsters in the age of 12–18 in most Western countries. In some countries, schools are obliged by law to run a specific program or “message” about drug use, other countries have adopted a simple “reference” in the national curriculum that attention has to be paid to health promotion in general, including drug prevention. The reason for this high priority for prevention programs is that drug use and abuse by youngsters is a major public health concern in most Western countries and the political will to address this problem is considerable.

Until now, there have been no objective criteria available for deciding which program is effective and which is not. This makes it difficult for schools, but also for policymakers and institutions that grant funds for such programs to make a well-founded choice among the available programs. One option is to use only programs that have been proven to be effective in well-conducted studies. Several of these programs are available, such as Life-Skills Training (Botvin, Baker, Dusenbury, & Botvin, 1995), the programs of Project Northland Komro et al., 2001, Perry et al., 1996, Project STAR (Pentz et al., 1989), or the “Healthy Schools and Drugs” Project (Cuijpers et al., 2002). However, most of these effective programs are specifically developed for use in the United States and it is not clear if they are suitable for use in other countries. They may not fit within other cultures, or they may be not effective in other cultures. Furthermore, many of the programs that have been proven to be effective are developed in research settings and may not fit easily within the standard practice of schools. For these reasons, it is important to develop quality standards in school-based drug prevention. These quality criteria can support not only schools and teachers, but policymakers and prevention workers as well in their choice of prevention programs. In this literature study, I systematically examine the current scientific knowledge about which characteristics determine the effectiveness of drug prevention programs.

There is no doubt that in the area of drug prevention, school-based interventions have been examined most extensively. In recent systematic literature searches, hundreds of studies examining the effects of school-based drug prevention were found, including dozens of well-designed high-quality studies Tobler et al., 2000, White & Pitts, 1998. It has been well established in these studies that school-based prevention programs can result in significant increases in knowledge about substances and in improved attitudes towards substance use. Well-designed prevention programs are also capable to reduce the use of substances significantly (Tobler et al., 2000), although these effects only last for a short period and maybe should be regarded as a short-term delay in the onset of substance use by nonusers and a short-term reduction in the amount of use by some current users.

Most research in this area, however, concentrates on the effectiveness of drug prevention programs. Relatively few studies have examined which characteristics are related to the effectiveness of the programs (Botvin, 2000). The number of studies examining the active ingredients, on the other hand, is growing and this review will summarize what is currently known about these ingredients.

In this study, I will concentrate on universal school-based drug prevention, aimed at tobacco, alcohol, and illegal drugs.

Universal prevention is aimed at all students, whether they are at high risk for drug use or not (Mrazek & Haggerty, 1994). Selective prevention (aimed at high-risk groups) and indicated prevention (aimed at students with beginning drug problems) are not included, as they focus only on subgroups of students. In this study, I focus on all substances, including tobacco, alcohol, marihuana, and other illegal drugs. Studies that aim at one substance and studies aimed at more substances at the same time are included.

There are several categories of studies that contain relevant information about the effective ingredients of drug prevention programs. In this review, I focus on three major categories of studies:

  • 1.

    Effect studies and meta-analyses. Studies examining the effects of school-based drug prevention program can result in knowledge about types of programs that are effective and types that are not effective. In this study, I focus on meta-analyses in which types of drug prevention programs are compared to each other. In meta-analyses, the results of several studies are statistically integrated and it is assumed that these meta-analyses result in a better estimate of the real effect of interventions than individual studies (Rosenthal & DiMatteo, 2001). If we can identify interventions that are effective and interventions that are not effective, we can use this knowledge to define quality criteria.

  • 2.

    Studies examining mediating variables of interventions. Some studies of school-based drug prevention programs examine which “mediators” (defined as characteristics of the programs) are causing the reduction in drug use.

  • 3.

    Studies comparing prevention programs. Several studies have examined characteristics of drug prevention programs, by comparing a program with the characteristic to the same program but without the characteristic. For example, many studies have compared peer- and adult-led prevention programs, prevention programs with and without booster sessions, and with or without community interventions.

In the next three sections of this paper, I will present the information that each of these three categories gives about the characteristics that determine the effectiveness of drug prevention programs. Then I will summarize these results and decide which evidence-based quality criteria can be defined.

Section snippets

The results of effect studies and meta-analyses

Several hundred studies have examined the results of drug prevention programs in schools. In these studies, many different interventions have been used. Most of these interventions are complex, consist of many different components, use multiple intervention techniques and strategies, and are based on many different theoretical models. Therefore, this large body of research does not result directly in evidence about which characteristics determine the effectiveness of the interventions.

Studies examining mediating variables of interventions

Another important source of information about the active ingredients of prevention programs is found in studies examining the “mediators” of change (characteristics of school-based drugs prevention programs that are related to the effects of the program on drug use; Donaldson et al., 1996, MacKinnon & Dwyer, 1993). These studies examine whether drug use is reduced by the intervention, whether the mediating variables are influenced by the intervention, and whether the mediating variables do have

Studies that directly compare prevention programs with and without possible mediators

Another important source of information about the effective ingredients of prevention programs is found in studies that directly compare a program with a certain characteristic to the same program but without the characteristic. I conducted a systematic literature search for these comparative studies. The results of this part of this study will be described in detail in a separate report, in which the literature search, the quality of the included studies, and the methods of analyzing the

Towards evidence-based quality criteria for school-based drug prevention

I reviewed three areas of research on effective characteristics of school-based drug prevention programs. Several quality criteria for prevention programs can be described on the basis of this research.

I assessed the strength of the evidence supporting each of the quality criteria, and distinguished four categories in the strength of evidence:

  • 1.

    Some evidence supporting the quality criterion (indicated by *); there is evidence from one of the three sources of evidence that supports this criterion

Discussion

I examined major categories of research on effective characteristics of school-based drug prevention programs and used these for defining quality criteria for prevention programs. This approach has several limitations. First, the interventions that are examined in the research I described are, as indicated earlier, very different from each other. It is very well possible that one mediating mechanism works in the context of one intervention, but not in another intervention. In other words, the

Acknowledgements

This study is conducted as a part of the “European Healthy School Project” and is supported by the European Program on Community Action on the Prevention of Drug Dependence.

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