Vapers exhibit similar subjective nicotine dependence but lower nicotine reinforcing value compared to smokers

Effects of dual use of e-cigarette and cannabis during adolescence on cigarette use in young adulthood

INTRODUCTION

E-cigarette and cannabis use by adolescents are risk factors for smoking initiation. We hypothesised that increasingly common dual use of e-cigarette and cannabis in adolescence leads to more frequent cigarette smoking in young adulthood.

METHODS

Data are from a prospective cohort study in Southern California, where 1164 participants who ever used nicotine products in their lifetime completed surveys in 12th grade (T1:2016), and at 24-month (T2) and 42-month (T3) follow-ups. Past 30-day use (number of days: range=0-30) of cigarettes, e-cigarettes and cannabis, and nicotine dependence, were assessed in each survey. Nicotine dependence for cigarettes and e-cigarettes was assessed using original and modified (for e-cigarette) Hooked on Nicotine Checklists (number of dependent products: range=0-2). Path analysis examined the mediation process via nicotine dependence linking baseline e-cigarette and cannabis use to subsequent increased cigarette use.

RESULTS

Baseline exclusive use of e-cigarettes (baseline prevalence, 2.5%) was associated with 2.61-fold increase in frequency of smoking days at T3 (95% CI 1.04 to 13.1), exclusive cannabis use (26.0%) with 2.58-fold increase (95% CI 1.43 to 4.98), and dual use (7.4%) with 5.84-fold increase (95% CI 3.16 to 12.81), compared with baseline non-users. Nicotine dependence at T2 mediated 10.5% (95% CI 6.3 to 14.7) and 23.2% (95% CI 9.6 to 36.3) of the association of cannabis and dual use, respectively, with increased smoking at T3.

DISCUSSION

Adolescent e-cigarette and cannabis use was associated with more frequent smoking during young adulthood, with larger effects of dual use. Associations were partially mediated through nicotine dependence. Dual use of cannabis and e-cigarettes may contribute to the development of nicotine dependence and increased use of combustible cigarettes.

A Close Look at Vaping in Adolescents and Young Adults in the United States

Vaping by adolescents and young adults is a legitimate concern as there is a risk that some may start smoking and that electronic cigarette (EC) use may have adverse effects in the developing lungs of adolescents. This commentary provides updated information on vaping patterns among adolescents and young adults in the United States, as well as the impact of EC usage on respiratory health. EC use has surged greatly among high school students and young adults over the last decade but fortunately has declined significantly since its peak in 2019. During the same time period, smoking rates have constantly fallen to new low record levels. These trends argue against EC use as a gateway to smoking. Most EC usage is infrequent and unlikely to increase a person's risk of negative health consequences. Furthermore, the majority of EC usage has happened among those who have previously smoked. There is a dearth of data on the long-term health implications of EC usage in adolescents and young adults. We do not know whether short-term or intermittent use of EC in youth can lead to negative health outcomes in adulthood, and long-term high-quality studies in well-defined groups are needed. Although vaping has been linked to respiratory symptoms, they tend to be transient and of uncertain significance. This commentary provides up-to-date information so health care providers can give objective and responsible medical advice on EC usage.