1. This webinar has been made possible with support from the
Canadian Institutes of Health Research
Welcome!
Preventing Alcohol
and Marijuana Use
Among Youth:
What’s the evidence?
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2. What’s the evidence?
 Lemstra, M., Bennett, N., Nannapaneni, U.,
Neudorf, C., Warren, L., Kershaw, T., Scott, C.
(2010). A systematic review of school-based
marijuana and alcohol prevention programs
targeting adolescents aged 10-15. Addiction
Research and Theory, 18(1): 84-96.
 http://www.health-evidence.ca/articles/show/20397

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4. This webinar has been made possible with support from the
Canadian Institutes of Health Research
Welcome!
Preventing Alcohol
and Marijuana Use
Among Youth:
What’s the evidence?

5. The Health Evidence Team
Kara DeCorby Heather Husson
Administrative Director Project Manager
Maureen Dobbins
Scientific Director
Tel: 905 525-9140 ext 22481
E-mail: dobbinsm@mcmaster.ca
Lori Greco Robyn Traynor Lyndsey McRae
Knowledge Broker Research Coordinator Research Assistant

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2. Relevant & current evidence
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8. Knowledge Translation
Supplement Project
CIHR-funded KTB-112487

9. Review
 Lemstra, M., Bennett, N., Nannapaneni, U., Neudorf,
C., Warren, L., Kershaw, T., Scott, C. (2010). A
systematic review of school-based marijuana
and alcohol prevention programs targeting
adolescents aged 10-15. Addiction Research and
Theory, 18(1): 84-96.

10. Evaluation
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survey link after the webinar.
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please e-mail Jennifer McGugan at
mcgugj@mcmaster.ca
to be sent the survey

11. Questions?

12. Summary Statement:
Lemstra (2010)
P 10-15 years
I (A) Knowledge-only program: Provision of anti-drug
information in school setting
(B) Comprehensive program: Intervention A plus
development of refusal, self- management, and social skills
C Usual care OR knowledge only (e.g., pamphlet)
O Primary outcome: Long-term reduction in
marijuana/alcohol use
Secondary Outcomes: Effectiveness of Intervention A
vs. Intervention B
Quality Rating: 9 (strong)

13. Overall Considerations
Comprehensive program: Mean reduction of
 12 days of alcohol use/month
 7 days of marijuana use/month
Knowledge-only program: Mean reduction of
 2 days of alcohol use/month (non-significant)
 25 days of marijuana use/month
Confounding factors not considered (e.g. age, gender,
socioeconomic status)

14. General Implications
Public health SHOULD promote / support / implement:
 School-based
 Comprehensive programs
 Minimum one year duration
 Knowledge-only programs (if comprehensive programming is not
possible)

15. Summary of Included Studies

16. What’s the evidence?
Comprehensive Programs
 Marijuana use
 Mean absolute reduction of 7 days/month (MUR
0.93, 95%CI 0.92-0.94) vs. no intervention
 Alcohol use
 Mean absolute reduction of 12 days/month (MUR
0.88, 95%CI 0.87-0.89) vs. no intervention

17. Comprehensive Programs
With & Without Stratification

18. Implications: Practice & policy
Comprehensive Programs
 Promote and support long-term comprehensive
programming to reduce alcohol and marijuana use
 Includes development of life skills, refusal skills and self-
management skills in programming
 Comprehensive programming is preferable to
knowledge-only for reducing alcohol and marijuana use

19. What’s the evidence?
Knowledge-only Programs
 Marijuana use
 Single study reported a significant reduction
 Mean absolute reduction of 25 days/month (MUR
0.75, 95% CI 0.63 – 0.87)
 Insufficient data to pool statistically
 Alcohol use
 Mean absolute reduction of 2 days/month (MUR
0.98, 95% CI 0.92-1.04)

20. Knowledge-only Programs
With & Without Stratification

21. Implications: Practice & policy
Knowledge-only Programs
 Shift existing knowledge-only programs to long-
term comprehensive programs to reduce
alcohol use
 New programming should include a skill
development focus to reduce both alcohol and
marijuana use

22. Overall Considerations
Comprehensive program: Mean reduction of
 12 days of alcohol use/month
 7 days of marijuana use/month
Knowledge-only program: Mean reduction of
 2 days of alcohol use/month (non-significant)
 25 days of marijuana use/month
Confounding factors not considered (e.g. age, gender,
socioeconomic status)

23. General Implications
Public health SHOULD promote / support / implement:
 School-based
 Comprehensive programs
 Minimum one year duration
 Knowledge-only programs if comprehensive programming is not
possible

24. Questions?

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26. Evaluation
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If you did not receive an email with a link to the
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