Mobile Phone Life-Skills Program Reduced Adolescent Cannabis Use by 45% at 18 Months
A text-message-based life-skills training program delivered to Swiss secondary school students reduced cannabis use prevalence by 45% and tobacco smoking by 33% at 18-month follow-up compared to controls.
Quick Facts
What This Study Found
At 18 months, the intervention group had significantly lower cannabis prevalence (OR=0.55, 95% CI 0.39-0.76) and tobacco prevalence (OR=0.67, 95% CI 0.47-0.96) compared to controls. Cannabis use days were also reduced (Cohen's d=-0.19). No effects were seen for problem drinking, alcohol quantity, or social skills.
Key Numbers
1,473 students, 89 school classes. 83.6% follow-up at 18 months. Cannabis prevalence: OR=0.55 (95% CI 0.39-0.76). Cannabis days: d=-0.19 (95% CI -0.29, -0.09). Tobacco: OR=0.67 (95% CI 0.47-0.96). No significant effects for problem drinking (OR=0.84), alcohol quantity, cigarette quantity, well-being, or social skills.
How They Did This
Two-arm cluster RCT with 1,473 students (mean age 15.4) across 89 Swiss school classes. The intervention consisted of 22 weeks of automated online feedback and individually tailored text messages based on social cognitive theory, addressing self-management, social skills, and substance resistance. Follow-up at 6 and 18 months.
Why This Research Matters
Digital prevention programs that work are rare. This study shows a fully automated, text-message-based program can produce lasting reductions in cannabis and tobacco use, which is significant because such programs can be scaled at minimal cost.
The Bigger Picture
The selective efficacy (cannabis and tobacco but not alcohol) mirrors other prevention programs and suggests that different substances may require different intervention strategies. The fully automated delivery makes this highly scalable across school systems.
What This Study Doesn't Tell Us
Conducted in Swiss secondary schools, so cultural context may affect generalizability. Self-reported outcomes. The intervention period (22 weeks) is substantial, and engagement may have varied. Effect sizes for cannabis use days were small (d=-0.19).
Questions This Raises
- ?Why does the program work for cannabis and tobacco but not alcohol?
- ?Would adaptation for other cultural contexts maintain efficacy?
- ?Do the effects persist beyond 18 months?
- ?What level of student engagement is needed for the program to be effective?
Trust & Context
- Key Stat:
- 45% reduction in cannabis prevalence at 18 months (OR=0.55)
- Evidence Grade:
- Strong: cluster RCT with adequate sample size, 83.6% follow-up at 18 months, and pre-registered design.
- Study Age:
- Published in 2022, with students recruited in 2019/2020.
- Original Title:
- Longer-Term Efficacy of a Digital Life-Skills Training for Substance Use Prevention.
- Published In:
- American journal of preventive medicine, 63(6), 944-953 (2022)
- Authors:
- Paz Castro, Raquel, Haug, Severin(4), Wenger, Andreas(3), Schaub, Michael P
- Database ID:
- RTHC-04132
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
How does a text message program prevent drug use?
The program delivered individually tailored messages over 22 weeks covering self-management skills, social skills, and resistance strategies. By meeting students on their phones rather than in classroom settings, it provided ongoing support and reinforcement.
Why did it work for cannabis but not alcohol?
The researchers did not identify a clear reason. One possibility is that cannabis and tobacco initiation may be more influenced by the self-management and resistance skills targeted by the program, while adolescent drinking patterns may be more socially embedded.
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Cite This Study
https://rethinkthc.com/research/RTHC-04132APA
Paz Castro, Raquel; Haug, Severin; Wenger, Andreas; Schaub, Michael P. (2022). Longer-Term Efficacy of a Digital Life-Skills Training for Substance Use Prevention.. American journal of preventive medicine, 63(6), 944-953. https://doi.org/10.1016/j.amepre.2022.06.017
MLA
Paz Castro, Raquel, et al. "Longer-Term Efficacy of a Digital Life-Skills Training for Substance Use Prevention.." American journal of preventive medicine, 2022. https://doi.org/10.1016/j.amepre.2022.06.017
RethinkTHC
RethinkTHC Research Database. "Longer-Term Efficacy of a Digital Life-Skills Training for S..." RTHC-04132. Retrieved from https://rethinkthc.com/research/paz-2022-longerterm-efficacy-of-a
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.