Among US youths aged 14-17, concurrent use of tobacco and cannabis was associated with nearly twice the odds of externalizing mental health problems compared to using either substance alone.
Pediatricians and school counselors working with adolescent substance use; public health professionals designing youth intervention programs.
62% of concurrent users had high externalizing problems vs 30% of nonusers
What the researchers found
Concurrent tobacco and cannabis users had significantly higher odds of externalizing problems compared to tobacco-only use (AOR 1.83) and cannabis-only use (AOR 1.85). High externalizing problems were most common in the concurrent group (61.6%), followed by cannabis-only (48.5%), tobacco-only (46.3%), and nonusers (30.4%). Internalizing problems did not significantly differ between substance use groups.
Why it matters
Tobacco and cannabis co-use is common among teens but rarely studied as a distinct pattern. Finding that the combination amplifies externalizing problems more than either substance alone suggests these users may need integrated interventions targeting both substances simultaneously.
The numbers in context
5,585 youths. Concurrent use prevalence: 3.4%. High externalizing problems: concurrent 61.6%, cannabis-only 48.5%, tobacco-only 46.3%, nonuse 30.4%. AOR for externalizing (concurrent vs tobacco-only): 1.83 (95% CI 1.15-2.91). AOR (concurrent vs cannabis-only): 1.85 (95% CI 1.11-3.06).
How the study worked
Cross-sectional analysis of PATH Study wave 6 data (nationally representative, March-November 2021). 5,585 youths aged 14-17. Past 30-day tobacco and cannabis use categorized into four exclusive groups. Mental health measured with the modified GAIN-Short Screener.
What this study cannot tell us
Cross-sectional design cannot determine whether co-use causes worse mental health or whether teens with existing behavioral problems are more likely to use both substances. Self-reported substance use and mental health. Data from 2021 during COVID-19 pandemic.
How to read the evidence
Nationally representative sample with validated measures, though cross-sectional design limits causal inference.
When this study was published
2024 study
The bigger picture
The specificity to externalizing problems (aggression, rule-breaking, impulsivity) rather than internalizing problems (depression, anxiety) raises questions about whether the combined neurochemical effects of nicotine and THC particularly affect impulse control and behavioral regulation in developing brains.
Questions still open
- Does the combination of nicotine and THC have synergistic neurological effects on adolescent impulse control? Would treating one substance use reduce the other?
Common questions
What are externalizing problems?
How common is concurrent tobacco and cannabis use among teens?
Read the original research
Concurrent Use of Tobacco and Cannabis and Internalizing and Externalizing Problems in US Youths.
JAMA network open, 7(7), e2419976
Citation
Do, Vuong V; Ling, Pamela M; Chaffee, Benjamin W; Nguyen, Nhung. (2024). Concurrent Use of Tobacco and Cannabis and Internalizing and Externalizing Problems in US Youths.. JAMA network open, 7(7), e2419976. https://doi.org/10.1001/jamanetworkopen.2024.19976
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