Among 1,661 Australian adolescents, depression and conduct problems were the strongest predictors of using alcohol, tobacco, and cannabis together, with 10% using multiple substances.
Parents, educators, prevention specialists, and anyone interested in why some teens use multiple substances.
Depression and conduct problems were strongest predictors; 10% of teens used multiple substances
What the researchers found
20.3% had used at least one substance in the past 30 days, 6.7% used two, and 3.3% used all three. The most common combination was alcohol+tobacco, followed by alcohol+cannabis. Conduct problems, depression, and school environment accounted for the most variance in poly drug use.
Why it matters
Prevention programs often target substances individually, but a third of substance-using teens used multiple substances. Targeting the underlying drivers, particularly depression and conduct problems, could be more efficient than substance-specific approaches.
The numbers in context
1,661 adolescents, ages 15-17. 20.3% used 1+ substance. 6.7% used 2. 3.3% used all 3. Most common combination: alcohol+tobacco, then alcohol+cannabis. Top predictors: conduct problems, depression, school environment.
How the study worked
Survey of 1,661 Australian adolescents aged 15-17 (50.9% male) assessing past 30-day use of alcohol, tobacco, and cannabis, with psychological, environmental, and demographic factors analyzed using weighted multilevel logistic regression.
What this study cannot tell us
Cross-sectional design cannot determine causation. Australian adolescent population may differ from other countries. Self-reported substance use. Past-30-day window may miss less frequent users.
How to read the evidence
Moderate: adequate sample with comprehensive predictor assessment, but cross-sectional Australian sample.
When this study was published
Published in 2019.
The bigger picture
The finding that psychological factors drive poly drug use more than demographic factors shifts the prevention conversation from "which kids use drugs" to "which psychological states drive drug use." Treating depression and conduct problems may be the most effective substance prevention strategy.
Questions still open
- Would treating adolescent depression and conduct problems reduce poly drug use? Are the predictors different for each substance combination? Could school environment interventions prevent poly drug use initiation?
Common questions
What drives teens to use multiple substances?
How common is poly drug use in teens?
Read the original research
Factors Associated with Poly Drug Use in Adolescents.
Prevention science : the official journal of the Society for Prevention Research, 20(5), 695-704
Citation
Jongenelis, Michelle; Pettigrew, Simone; Lawrence, David; Rikkers, Wavne. (2019). Factors Associated with Poly Drug Use in Adolescents.. Prevention science : the official journal of the Society for Prevention Research, 20(5), 695-704. https://doi.org/10.1007/s11121-019-00993-8
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