Substance Use among Exclusive Electronic Cigarette Users and Dual Combustible Cigarette Users: Extending Work to Adult Users

Evidence update on e-cigarette dependence: A systematic review and meta-analysis

INTRODUCTION

We conducted this review to examine the risk of e-cigarette dependence in different populations by updating the review on this topic by the National Academies of Science, Engineering, and Medicine.

METHODS

Six academic databases were searched for studies published between September 2017 and December 2023. We included peer-reviewed human, animal, cell/in vitro original studies examining associations of e-cigarette use and dependence but excluded qualitative studies. Three types of e-cigarette exposure were examined: acute, short-to-medium term, and long-term. Meta-analysis were conducted when possible. Different risk of bias tools were used for assessing quality of the included human studies.

RESULTS

We included 107 studies, of which 34 studies were included in the subgroup analysis. Meta-analyses showed that non-smoker current vapers had no statistically significant difference in level or prevalence of dependence compared to non-vaper current smokers and dual users. However, never smoker current vapers had a lower level of dependence (SMD -0.723, p < 0.01) compared to dual users, which was also supported by ANOVA test. Narrative review findings suggest that nicotine vapers had higher level of dependence than non-nicotine vapers and e-cigarette dependence is positively associated with nicotine concentration, frequency, and duration of use. No strong relationship was found between dependence and product types or features. Socio-demographic factor-based subgroup findings were inconclusive.

CONCLUSIONS

The level and prevalence of e-cigarette dependence is similar to cigarette dependence. There was high variability in the definitions and methods used for defining populations and assessing dependence. Further research and monitoring are crucial.

Young Adult E-Cigarette and Combustible Tobacco Users Attitudes, Substance Use Behaviors, Mental Health, and Neurocognitive Performance

Nicotine and tobacco product (NTP) use has escalated, largely due to the advent of e-cigarettes. The NTP administration method (i.e., combustible cigarette, e-cigarette) may be an important differentiator. We assessed young adult substance use history, nicotine attitudes, mental health, and neurocognition by the NTP use method. Emerging adults (16–22 year olds) were divided into combustible NTP users (Combustible+ = 79, had used any combustible NTP in the last 6 months), non-combustible users (E-Cig = 43, had used non-combustible NTP, in the past 6 months), and NTP Naïve (n = 79; had not used NTP in the past 6 months) based on past 6-month NTP use patterns. Participants completed self-report and objective neurocognition measures. Analysis of covariance assessed mental health and neurocognition by group, controlling for confounds and correcting for multiple comparisons. Nicotine groups reported more favorable attitudes toward combustible cigarette and e-cigarette use, with taste as the primary reason for e-cigarette use. Combustible+ reported more nicotine dependence and craving. Substance use differed by group, with Combustible+ using the most NTP, alcohol, and cannabis. Nicotine groups reported higher depression and stress symptoms; male Combustible+ reported higher depression symptoms than other same-gender groups. Groups did not differ on neurocognition, though cannabis use was associated with inaccurate emotional Stroop responses. Overall, research suggests that young adult combustible users are likely qualitatively different from non-combustible users. Understanding the unique characteristics related to NTP product use will help guide intervention and prevention development.