Web-Based School Program Reduced Adolescent Drinking but Not Cannabis Use | Research

The takeaway

A web-based prevention program delivered to over 6,000 Australian students increased alcohol and cannabis knowledge and reduced alcohol uptake, but did not significantly affect cannabis use.

School administrators considering evidence-based prevention curricula; public health researchers studying adolescent substance prevention.

51% reduction in heavy episodic drinking (OR 0.49)

What the researchers found

Students who received the Climate Schools program were 38% less likely to drink a full standard drink and 51% less likely to engage in heavy episodic drinking compared to controls at 12-month follow-up.

Why it matters

Few substance prevention programs for adolescents have demonstrated replicable effects. This large replication trial confirmed the program works for reducing alcohol use, which matters for schools choosing evidence-based curricula.

The numbers in context

Alcohol knowledge increased (standardized mean difference 0.51). Cannabis knowledge increased (SMD 0.49). Odds of drinking a full drink reduced by 38% (OR 0.62, p=0.014). Heavy episodic drinking reduced by 51% (OR 0.49, p=0.022). Cannabis use showed no significant difference (OR 0.57, p=0.22).

How the study worked

Cluster-randomized controlled trial across 71 secondary schools in three Australian states. Year 8 students (approximately age 13-14) received either the web-based Climate Schools: Alcohol and Cannabis course (n=3,236) or standard health education (n=3,150). Outcomes measured at baseline, 6, and 12 months.

What this study cannot tell us

The study relied on self-reported substance use. The program was developed for an Australian context and may not generalize to other countries. The 12-month follow-up is relatively short for assessing long-term prevention effects.

How to read the evidence

Strong: large cluster-RCT with over 6,000 students across 71 schools in three states, replicating prior findings.

When this study was published

Published in 2022.

The bigger picture

This is one of the first large-scale replication trials for a web-based substance prevention program. The fact that it replicated alcohol effects but not cannabis effects raises questions about whether different strategies are needed for cannabis-specific prevention.

Questions still open

Why did the program reduce alcohol but not cannabis use despite increasing cannabis knowledge? Would a cannabis-specific adaptation produce better outcomes? Do prevention effects persist beyond 12 months?

Common questions

Why did the program work for alcohol but not cannabis?

The researchers suggest the program may need cannabis-specific adaptations. Knowledge alone may not be sufficient to change cannabis behavior, or the 12-month window may have been too short to detect differences given lower baseline cannabis use rates.

Is the Climate Schools program available outside Australia?

The study tested it in Australia. International adaptations would need to account for cultural differences in drinking and drug use patterns.

Read the original research

A national effectiveness trial of an eHealth program to prevent alcohol and cannabis misuse: responding to the replication crisis.

Psychological medicine, 52(2), 274-282

View on PubMed ↗Publisher’s paper ↗

Citation

Newton, Nicola C; Chapman, Cath; Slade, Tim; Birrell, Louise; Healy, Annalise; Mather, Marius; McBride, Nyanda; Hides, Leanne; Allsop, Steve; Mewton, Louise; Andrews, Gavin; Teesson, Maree. (2022). A national effectiveness trial of an eHealth program to prevent alcohol and cannabis misuse: responding to the replication crisis.. Psychological medicine, 52(2), 274-282. https://doi.org/10.1017/S0033291720001919