In 4,031 U.S. young adults, the 'gateway' effect was bidirectional — cigarettes, e-cigarettes, cigars, and alcohol all predicted cannabis initiation, but cannabis equally predicted initiation of all four other substances, with stronger effects when initiation occurred before age 18.
Substance use prevention specialists, policymakers debating gateway claims, and educators working with adolescents and young adults.
What the researchers found
Initiating cigarettes, e-cigarettes, cigars, or alcohol increased the hazard of starting cannabis (aHRs 2.17–3.78). Conversely, initiating cannabis increased the hazard of starting each of those substances equally strongly (aHRs 3.07–3.73). All associations were stronger when initiation occurred at ages 5–18 vs. after 18. Depression predicted cannabis initiation specifically.
Why it matters
The traditional 'gateway hypothesis' positions cannabis as a stepping stone to harder drugs. This study shows the gateway effect works equally in both directions — using any substance increases the hazard of initiating others, challenging the idea that cannabis is uniquely dangerous as a gateway.
The numbers in context
4,031 young adults. Lifetime use: cannabis 68%, cigarettes 45%, e-cigarettes 49%, cigars 31%, alcohol 85%. Cannabis → cigarettes aHR 3.51. Cannabis → e-cigarettes aHR 3.73. Cannabis → cigars aHR 3.66. Cannabis → alcohol aHR 3.07. All effects stronger at ages 5–18.
How the study worked
Discrete-time survival analysis of 2023 survey data from 4,031 U.S. young adults (mean age 26.29). Self-reported age of initiation for each substance enabled time-lagged hazard modeling. Adjusted for demographics, state cannabis laws, lifetime mental health diagnoses, and personality traits.
What this study cannot tell us
Retrospective recall of initiation ages may be inaccurate. Cross-sectional survey with survival analysis provides temporal ordering but not true prospective data. Cannabis use was very common (68%), potentially limiting generalizability. Cannot account for all confounders.
How to read the evidence
Large sample (4,031) with sophisticated survival analysis modeling temporal sequences, though retrospective recall and cross-sectional design limit causal conclusions.
When this study was published
Published 2025, 2023 survey data.
The bigger picture
Rather than cannabis being a unique gateway, this study suggests a 'common liability' model — individuals who initiate any substance are more likely to initiate others, driven by shared underlying factors like personality, mental health, and social environment. This has major implications for prevention strategy.
Questions still open
- Should prevention programs target underlying factors (personality, mental health) rather than specific substances? Does the adolescent-specific amplification of gateway effects justify different policies for under-18 access? Would delaying initiation of any substance reduce cascade effects?
Common questions
Is cannabis a gateway drug?
Why are the effects stronger in adolescents?
Read the original research
The gateway effect of cigarette, e-cigarette, cigar, and alcohol use vs. Cannabis use.
Addictive behaviors, 170, 108451
Citation
Wang, Yan; Cavazos-Rehg, Patricia A; Cui, Yuxian; Speer, Morgan; LoParco, Cassidy R; McCready, Darcey M; Yang, Y Tony; Berg, Carla J. (2025). The gateway effect of cigarette, e-cigarette, cigar, and alcohol use vs. Cannabis use.. Addictive behaviors, 170, 108451. https://doi.org/10.1016/j.addbeh.2025.108451
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