Aim: This study investigates the association between two types of social relations during leisure time (to parents and peers) and the frequency of alcohol use among Swedish adolescents, taking possible interaction effects into account. Methods: The data were collected during the 1995-2005 time period by using a questionnaire handed out in the…

Aim: To test whether the school-based Olweus prevention programme against bullying may have lasting effects on substance use, a hypothesis based on the characteristics of bullies having misconduct behaviour associated with substance use. Methods: The Olweus programme was introduced from grades 7 through 9 in four schools and monitored up to grade…

Aims: To investigate the links between the visibility of cannabis use in school (measured by teachers' reports of students being under the influence of cannabis on school premises), the proportion of cannabis users in the class, perceived availability of cannabis, as well as adolescent cannabis use. Methods: A multilevel regression model was…