It is About Time to Drop The Ridiculous Gateway Theory Once and for All

The "Gateway Theory" which states that vaping can lead to regular smoking, especially among adolescents, has been debunked by countless peer reviewed studies over the years. Yet, it is still used as a justification to set unreasonable vape restrictions.

Diane Caruana

August 29, 2024

Supporters of the theory argue that experimenting with electronic nicotine delivery systems (ENDS) like vapes makes individuals more likely to transition to smoking tobacco cigarettes due to the addictive nature of nicotine and behaviours associated with both activities. They suggest that the use of flavoured vapes, which appeal to younger individuals, increases the likelihood of nicotine dependence and eventually, experimentation with traditional smoking. This already raises an obvious question: if it is the sweet candy flavours attracting young people to vaping, why on earth would they transition to smelly and flavourless (or at best menthol flavoured) cigarettes?

Critics of the theory have long highlighted that it is based on correlational evidence and does not establish a direct causal relationship. A recent paper by Arielle Selya, PhD, published in the journal Harm Reduction, challenged the “gateway” hypothesis once again, and compared it outdated theories such as one claiming that cannabis use leads to the use of harder drugs

In fact, the Institute of Medicine of the National Academy of Sciences had found no conclusive evidence indicating that cannabis use causes the abuse of other drugs, instead suggesting that alcohol and nicotine use typically precede both cannabis and other illicit drug use. This finding aligns with the “common liability” hypothesis, which proposes that users of different substances share common risk factors or tendencies. In the context of vaping and smoking, the shared factor is nicotine.

Dr. Selya reiterated that rather than vaping leading directly to cigarette smoking, a pre-existing inclination to use nicotine products might explain why some youths use both. She introduced the concept of the “counterfactual,” asking what these youths would do in a world without e-cigarettes, and the answer is smoke, they in fact did in the past. This perspective is supported by data showing a decline in youth tobacco smoking since 2004, and accelerated declines following the introduction of e-cigarettes.

Policymakers, she argues, should not restrict adult access to e-cigarettes based on concerns about youth use, especially as it is already illegal for minors to purchase these products. Instead, they should consider the potential benefits of e-cigarettes as harm reduction tools and the counterfactual scenario if these products were not available.

Yet another example of irresponsibly inferring causation from a correlation

Shared personality factors, such as susceptibility to risk-taking behaviours, could explain why individuals who vape might also be more likely to smoke.

In recent years there have been several peer-reviewed studies and expert reviews reporting findings which challenge the gateway theory. A 2018 comprehensive report by the National Academies of Sciences, Engineering, and Medicine, found substantial evidence indicating that that vaping increases the risk of ever using combustible tobacco cigarettes among youth and young adults. However, they also noted that there is limited evidence on whether this translates to regular use of combustible tobacco products, which is more indicative of addiction.

A 2017 study by Soneji et al., published in Tobacco Control, consisted of a systematic review and meta-analysis on the association between vaping and subsequent smoking initiation among adolescents. The research team wrote that while they identified an association, causation was difficult to establish due to the confounding factors and the possibility that common risk factors drive both behaviours.

While a study Hajek et al. published in Addiction in 2019, reviewed the evidence and concluded that while some young people who vape may later experiment with smoking, the overall effect of vaping is to reduce smoking rates among youth. This suggests that vaping may be displacing smoking rather than acting as a gateway to it.

The “common liability” model as a more plausible explanation

An earlier (2020) study by Arielle Selya and her team published in Addiction, challenged the gateway theory by proposing the “common liability” model. They argued that rather than vaping leading to smoking, underlying risk factors (like personality traits and environmental influences) make some individuals more likely to use both e-cigarettes and combustible cigarettes.

In line with Selya’s arguments, on exploring the concept of common liability, Harte et al. (2022) found that shared factors, such as susceptibility to risk-taking behaviours, could explain why individuals who vape might also be more likely to smoke.

While multiple Public Health England (PHE) reports have consistently found no significant evidence to support the gateway theory. They noted that regular vaping is rare among non-smokers and that youth smoking rates have continued to decline even with the rise of vaping.

These studies all suggest that the observed association between vaping and subsequent smoking does not imply a direct causal relationship, but rather reflect pre-existing propensities towards both behaviours. The “common liability” model is often presented as an alternative and more plausible explanation, suggesting that the same factors that predispose individuals to try vaping might also predispose them to try smoking.