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J Adolesc Health. 2014 May;54(5):565-73. doi: 10.1016/j.jadohealth.2013.10.009. Epub 2013 Dec 10.

Short-term mediating factors of a school-based intervention to prevent youth substance use in Europe.

Author information

Center for Developmental Research, Örebro University, Örebro, Sweden. Electronic address:
Department of Clinical and Biological Sciences, University of Torino, Torino, Italy; Piedmont Centre for Drug Addiction Epidemiology, ASL TO3, Torino, Italy.
Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden; Centre for Epidemiology and Community Medicine, Stockholm Health Care District, Stockholm, Sweden.
Department of Life, Health and Environmental Sciences, University of Aquila, L'Aquila, Italy.
Piedmont Centre for Drug Addiction Epidemiology, ASL TO3, Torino, Italy; Department of Translational Medicine, Avogadro University, Novara, Italy.



To investigate factors mediating the effects of a European school-based intervention (Unplugged) based on a social influence approach to youths' substance use.


Schools in seven European countries (n = 143, including 7,079 pupils) were randomly assigned to an experimental condition (Unplugged curriculum) or a control condition (usual health education). Data were collected before (pretest) and 3 months after the end of the program (posttest). Multilevel multiple mediation models were applied to the study of effect mediation separately for tobacco, alcohol, and cannabis use. Analyses were conducted on the whole sample, and separately on baseline users and nonusers of each substance.


Compared with the control group, participants in the program endorsed less positive attitudes toward drugs; positive beliefs about cigarettes, alcohol, and cannabis; and the normative perception of peers using tobacco and cannabis. They also increased in knowledge about all substances and refusal skills toward tobacco. Decreased positive attitudes toward drugs, increase in refusal skills, and reappraisal of norms about peer using tobacco and cannabis appeared to mediate the effects of the program on the use of substances. However, mediating effects were generally weak and some of them were only marginally significant.


This study lends some support to the notion that school-based programs based on a social influence model may prevent juvenile substance use through the modification of attitudes, refusal skills, and normative perceptions.


Alcohol; Cannabis; Mediation; Prevention; School-based intervention; Social influence approach; Substance use; Tobacco

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