Young adult e-cigarette use
: who uses e-cigarettes, why, and what are the potential consequences?

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


E-cigarettes are popular and effective smoking cessation aids, but there are concerns about the consequences of their use. Specifically, young people who have never smoked before may use e-cigarettes and this may lead to smoking initiation. Additionally, there are fears that long-term e-cigarette use may cause health issues.
To fully understand the potential impact of e-cigarette use and to inform policy, it is vital to understand who uses e-cigarettes, why, and what the potential consequences of use are – questions which are explored in this thesis. To investigate the likely harms of e-cigarette use, I have used novel methods to explore whether e-cigarettes may act as a gateway to smoking and explore what the health consequences of e-cigarette use may be.
First, I conducted a meta-analysis of studies exploring whether e-cigarette use acts as a gateway to smoking among young people. Second, I explored which young adults are most likely to vape and whether different reasons for vaping are associated with continued smoking. Third, I explored whether there is a shared genetic liability for smoking initiation and e-cigarette use in a cohort of young adults. Fourth, I investigated whether nicotine use without exposure to cigarette smoke (e.g., via e-cigarettes) may cause smoking-related poor health outcomes using a variety of Mendelian randomisation methods in a cohort of adults. Finally, I began to explore the relationship between nicotine and BMI in an experimental study of adults.
Overall, I found little evidence that e-cigarettes act as a gateway to smoking, however, smokers and vapers share common characteristics and may share a genetic predisposition to risk-taking. There was little evidence of nicotine use causing poor health outcomes without tobacco smoke exposure. The evidence suggests policies should encourage smokers to switch to vaping. Further research is needed to explore these findings using emerging methods and data.
Date of Award23 Mar 2021
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorAmy E Taylor (Supervisor), Marcus R Munafo (Supervisor) & Robyn Wootton (Supervisor)


  • E-cigarettes
  • Gateway hypothesis
  • Common liability
  • Nicotine

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