Delivering prevention for alcohol and cannabis using the Internet: a cluster randomised controlled trial.

Objective: To establish the efficacy of an internet based prevention program to reduce alcohol and cannabis use in adolescents.

Method: A cluster randomised controlled trial was conducted with 764 13-year olds from ten Australian secondary schools in 2007-2008. Half the schools were randomly allocated to the computerised prevention program (n=397), and half to their usual health classes (n=367). The Climate Schools: Alcohol and Cannabis prevention course is facilitated by the internet and consists of novel, evidence-based, curriculum consistent lessons aimed at reducing alcohol and cannabis use. Participants were assessed at baseline, immediately post, and at six months following the intervention.

Results: Compared to the control group, students in the intervention group showed significant improvements in alcohol and cannabis knowledge at the end of the course and the six month follow-up. In addition, the intervention group showed a reduction in average weekly alcohol consumption and frequency of cannabis use at the six month follow-up. No differences between groups were found on alcohol expectancies, cannabis attitudes, or alcohol and cannabis related harms.

Conclusions: The course is acceptable, scalable and fidelity is assured. It increased knowledge regarding alcohol and cannabis, and decreased use of these drugs.