The Gateway Goes Both Ways: Cannabis Predicts Other Substance Use Just as Much as They Predict Cannabis
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.
Quick Facts
What This Study 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.
Key Numbers
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 They Did This
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.
Why This Research 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 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.
What This Study Doesn't 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.
Questions This Raises
- ?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?
Trust & Context
- Key Stat:
- Evidence Grade:
- Large sample (4,031) with sophisticated survival analysis modeling temporal sequences, though retrospective recall and cross-sectional design limit causal conclusions.
- Study Age:
- Published 2025, 2023 survey data.
- Original Title:
- The gateway effect of cigarette, e-cigarette, cigar, and alcohol use vs. Cannabis use.
- Published In:
- Addictive behaviors, 170, 108451 (2025)
- Authors:
- Wang, Yan(20), Cavazos-Rehg, Patricia A(14), Cui, Yuxian(13), Speer, Morgan, LoParco, Cassidy R, McCready, Darcey M, Yang, Y Tony, Berg, Carla J
- Database ID:
- RTHC-07921
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Is cannabis a gateway drug?
This study shows cannabis can precede other substance initiation, but the effect is equally strong in the reverse direction — tobacco, alcohol, and e-cigarettes also 'gateway' to cannabis just as powerfully. The evidence supports a bidirectional relationship driven by shared risk factors.
Why are the effects stronger in adolescents?
Associations between substance initiation were significantly stronger at ages 5–18 than after 18, likely because the adolescent brain is more sensitive to rewarding experiences, and early substance use occurs in a more socially influenced context.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-07921APA
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
MLA
Wang, Yan, et al. "The gateway effect of cigarette, e-cigarette, cigar, and alcohol use vs. Cannabis use.." Addictive behaviors, 2025. https://doi.org/10.1016/j.addbeh.2025.108451
RethinkTHC
RethinkTHC Research Database. "The gateway effect of cigarette, e-cigarette, cigar, and alc..." RTHC-07921. Retrieved from https://rethinkthc.com/research/wang-2025-the-gateway-effect-of
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.