Measuring e-cigarette addiction among adolescents

Do sociodemographic risk profiles for adolescents engaging in weekly e-cigarette, cigarette, and dual product use differ?

BACKGROUND

E-cigarette use represents a contemporary mode of nicotine product use that may be changing the risk profile of participating adolescents. Understanding differences in sociodemographic characteristics of adolescents engaging in contemporary e-cigarette use and traditional cigarette use is important for effectively developing and targeting public health intervention programs. The objective of this study was to identify and compare sociodemographic risk profiles for exclusive e-cigarette use and dual-product use among a large sample of Canadian youth.

METHODS

A survey of 46,666 secondary school students in the 2021-22 wave of the COMPASS study measured frequency of past month e-cigarette and cigarette use as well as age, sex, gender, racial or ethnic background, spending money, relative family affluence, and having one's own bedroom. Rates of cigarette-only, e-cigarette-only, and dual product use were calculated, and separate classification trees were run using the CART algorithm to identify sociodemographic risk profiles for weekly dual-product use and weekly e-cigarette-only use.

RESULTS

Over 13% of adolescents used only e-cigarettes at least weekly, 3% engaged in weekly dual e-cigarette and cigarette use, and less than 0.5% used only cigarettes. Available spending money was a common predictor of dual-product and e-cigarette-only use. Gender diverse youth and youth with lower perceived family affluence were at higher risk for dual-product use, while white and multiethnic adolescents were at greater risk of e-cigarette-only use. Two high-risk profiles were identified for e-cigarette-only use and four high-risk profiles were identified for dual product use.

CONCLUSIONS

This study used a novel modelling approach (CART) to identify combinations of sociodemographic characteristics that profile high-risk groups for exclusive e-cigarette and dual-product use. Unique risk profiles were identified, suggesting that e-cigarettes are attracting new demographics of adolescents who have not previously been considered as high-risk for traditional cigarette use.

Nicotine dependence among undergraduates who use nicotine salt-based e-cigarettes

OBJECTIVE

This study examined the relationship between use patterns of a popular e-cigarette brand using nicotine salts, JUUL, and symptoms of nicotine dependence in a college cohort.

PARTICIPANTS

Data for this study came from a prospective cohort of undergraduate students at a large Midwestern university from 2018 to 2019.

METHODS

Among participants who had ever tried a JUUL (N = 411), univariate and multivariable logistic regression were used to test the associations between use frequency (past 30-day use) and quantity (time to finish a pod) and nicotine dependence at follow up.

RESULTS

In the multivariable models, both frequency of use and quantity of use were associated with subsequent nicotine dependence, based on most indicators of dependence.

CONCLUSIONS

As salt-based nicotine is now present in the most popular e-cigarette brands used by young people, such findings inform our contemporary understanding of e-cigarettes' addictive potential and can help inform campus-based interventions.

Chronic exposure to cigarette smoke extract increases nicotine withdrawal symptoms in adult and adolescent male rats

The aim of the current study was to determine whether non-nicotine constituents of cigarette smoke contribute to nicotine dependence in adolescent and adult male Sprague Dawley rats. For 10 days animals were given three times daily intravenous injections of nicotine (1.5 mg/kg/day) or cigarette smoke extract (CSE) containing an equivalent dose of nicotine. Both spontaneous and mecamylamine-precipitated withdrawal were then measured. Chronic treatment with CSE induced significantly greater somatic and affective withdrawal signs than nicotine in both adolescents and adults. Mecamylamine-precipitated somatic signs were similar at both ages. In contrast, animals spontaneously withdrawn from chronic drug treatment exhibited significant age differences: whereas adolescents chronically treated with nicotine did not show somatic signs, those treated with CSE showed similar physical withdrawal to those of adults. Mecamylamine did not precipitate anxiety-like behavior at either age. However, both adolescents and adults showed significant anxiety in a light-dark box test 18 h after spontaneous withdrawal. Anxiety-like behavior was still evident in an open field test 1 month after termination of drug treatment, with adolescents showing significantly greater affective symptoms than adults. Our findings indicate that non-nicotine constituents of cigarette smoke do contribute to dependence in both adolescents and adults and emphasize the importance of including smoke constituents with nicotine in animal models of tobacco dependence.

Nicotine dependence and associated factors among persons who use electronic e-cigarettes in Malaysia - an online survey

BACKGROUND

Nicotine dependence, factors associated with dependence, and self-reported side effects among people who use e-cigarettes are scarce in developing countries.

METHODS

A sample of 302 persons who currently use e-cigarettes was recruited from discussion forums on Reddit, Facebook, and the forum 'lowyat'. The online Google form survey collected data on demographics, e-cigarette use, and the reasons, for cigarette smoking, Fagerstorm Test for Nicotine Dependence adapted for e-cigarettes (eFTND), and side effects experienced.

RESULTS

The mean age was 25.5 years (6.5), 60.6% were males and 86% had higher education. About 47% were using e-cigarettes only, 27.8% were currently using dual products (both electronic and conventional cigarettes), and 25.2% had also smoked cigarettes in the past. 'Less harmful than cigarettes' (56.3%), 'because I enjoy it' (46.7%), and 'it has a variety of flavors (40.4%) were the common reasons for e-cigarette use. The mean eFTND score was 3.9 (SD = 2.2), with a median of four side effects (IQR 3-6), sore or dry mouth/throat (41.4%), cough 33.4%, headache (20.5%), dizziness (16.2%) were commonly reported side effects. eFTND score and side effects were higher among persons using dual products. By multiple linear regression analysis, males (β = 0.56 95% CI 0.45, 1.05, p = 0.033), dual-use (β = 0.95 95% CI 0.34, 1.56, p < 0.003), and use of nicotine-containing e-cigarettes (β = 0.66 95% CI 0.07, 1.25 p = 0.024) had higher eFTND score.

CONCLUSION

Our findings of the study call for the placement of disclaimers about possible nicotine addiction and side effects of e-cigarette products.

Psychosocial stressors and current e-cigarette use in the youth risk behavior survey

BACKGROUND

This study explores the association between psychosocial stressors and current e-cigarette use among adolescents in the United States.

METHODS

We used data from 12,767 participants in the 2019 National Youth Risk Behavioral Survey to examine the association between psychosocial stressors (bullying, sexual assault, safety-related absence from school, depressive symptoms, suicidal ideation, physical altercation, and weapon threats) and past-30-day e-cigarette use using multivariable-adjusted logistic regression models. We examined the association for each stressor and then as a burden score (0-7). To compare the strength of the association between stressors and current e-cigarette use to current combustible cigarette use, we additionally examined the association between each stressor and current combustible cigarette use.

RESULTS

Approximately 32.7% reported current e-cigarette use. The weighted prevalence of current e-cigarette use was higher among individuals who experienced stressors than those who did not. For example, bullying (43.9% vs. 29.0%). Similar prevalence patterns were seen among other stressors. Individuals who experienced stressors had significantly higher adjusted odds of current e-cigarette use than those who did not (OR [Odds Ratio] range: 1.47-1.75). Similarly, individuals with higher burden scores had a higher prevalence (zero [20.5%], one [32.8%], two [41.4%], three [49.6%], four to seven [60.9%]) and higher odds of current e-cigarette use (OR range: 1.43-2.73) than those with a score of zero. The strength of the association between the stressors and e-cigarette use was similar to that between the stressors and combustible cigarette use.

CONCLUSION

The study demonstrates a significant association between psychosocial stressors and adolescent e-cigarette use, highlighting the potential importance of interventions, such as targeted school-based programs that address stressors and promote stress management, as possible means of reducing adolescent e-cigarette use. Future research directions include exploring underlying mechanisms linking stressors to e-cigarette use and evaluating the effectiveness of interventions addressing stressors in reducing adolescent e-cigarette use.

Nicotine Vaping and Co-occurring Substance Use Among Adolescents in the United States from 2017-2019

Background: The use of electronic cigarettes (or "vaping") among adolescents remains a public health concern given exposure to harmful substances, plus potential association with cannabis and alcohol. Understanding vaping as it intersects with combustible cigarette use and other substance use can inform nicotine prevention efforts. Methods: Data were drawn from 51,872 US adolescents (grades 8, 10, 12, years: 2017-2019) from Monitoring the Future. Multinomial logistic regression analyses assessed links of past 30-day nicotine use (none, smoking-only, vaping-only, and any smoking plus vaping) with both past 30-day cannabis use and past two-week binge drinking. Results: Nicotine use patterns were strongly associated with greater likelihood of cannabis use and binge drinking, particularly for the highest levels of each. For instance, those who smoked and vaped nicotine had 36.53 [95% CI:16.16, 82.60] times higher odds of having 10+ past 2-week binge drinking instances compared to non-users of nicotine. Discussion: Given the strong associations between nicotine use and both cannabis use and binge drinking, there is a need for sustained interventions, advertising and promotion restrictions, and national public education efforts to reduce adolescent nicotine vaping, efforts that acknowledge co-occurring use.

Rat bronchoalveolar lavage proteome changes following e-cigarette aerosol exposures

E-cigarette liquids are complex mixtures of chemicals consisting of humectants, such as propylene glycol (PG) and vegetable glycerin (VG), with nicotine or flavorings added. Published literature emphasizes the toxicity of e-cigarette aerosols with flavorings whereas much less attention has been given to the biologic effects of humectants. The purpose of the current study was to provide a comprehensive view of the acute biologic effects of e-cigarette aerosols on rat bronchoalveolar lavage (BAL) using mass spectrometry-based global proteomics. Sprague-Dawley rats were exposed to e-cigarette aerosol for 3 h/day for three consecutive days. Groups included: PG/VG alone, PG/VG + 2.5% nicotine (N), or PG/VG + N + 3.3% vanillin (V). Right lung lobes were lavaged for BAL and supernatants prepared for proteomics. Extracellular BAL S100A9 concentrations and BAL cell staining for citrullinated histone H3 (citH3) were also performed. From global proteomics, ∼2,100 proteins were identified from rat BAL. The greatest change in number of BAL proteins occurred with PG/VG exposures alone compared with controls with biological pathways enriched for acute phase responses, extracellular trap formation, and coagulation. Extracellular BAL S100A9 concentrations and the number of citH3 + BAL cells also increased significantly in PG/VG and PG/VG + 2.5% N. In contrast to PG/VG or PG/VG + N, the addition of vanillin to PG/VG + N increased BAL neutrophilia and downregulated lipid transport proteins. In summary, global proteomics support e-cigarette aerosol exposures to PG/VG alone as having a significant biologic effect on the lung independent of nicotine or flavoring with increased markers of extracellular trap formation.

Study protocol of the Our Futures Vaping Trial: a cluster randomised controlled trial of a school-based eHealth intervention to prevent e-cigarette use among adolescents

BACKGROUND

Effective and scalable prevention approaches are urgently needed to address the rapidly increasing rates of e-cigarette use among adolescents. School-based eHealth interventions can be an efficient, effective, and economical approach, yet there are none targeting e-cigarettes within Australia. This paper describes the protocol of the OurFutures Vaping Trial which aims to evaluate the efficacy and cost-effectiveness of the first school-based eHealth intervention targeting e-cigarettes in Australia.

METHODS

A two-arm cluster randomised controlled trial will be conducted among Year 7 and 8 students (aged 12-14 years) in 42 secondary schools across New South Wales, Western Australia and Queensland, Australia. Using stratified block randomisation, schools will be assigned to either the OurFutures Vaping Program intervention group or an active control group (health education as usual). The intervention consists of four web-based cartoon lessons and accompanying activities delivered during health education over a four-week period. Whilst primarily focused on e-cigarette use, the program simultaneously addresses tobacco cigarette use. Students will complete online self-report surveys at baseline, post-intervention, 6-, 12-, 24-, and 36-months after baseline. The primary outcome is the uptake of e-cigarette use at 12-month follow-up. Secondary outcomes include the uptake of tobacco smoking, frequency/quantity of e-cigarettes use and tobacco smoking, intentions to use e-cigarettes/tobacco cigarettes, knowledge about e-cigarettes/tobacco cigarettes, motives and attitudes relating to e-cigarettes, self-efficacy to resist peer pressure and refuse e-cigarettes, mental health, quality of life, and resource utilisation. Generalized mixed effects regression will investigate whether receiving the intervention reduces the likelihood of primary and secondary outcomes. Cost-effectiveness and the effect on primary and secondary outcomes will also be examined over the longer-term.

DISCUSSION

If effective, the intervention will be readily accessible to schools via the OurFutures platform and has the potential to make substantial health and economic impact. Without such intervention, young Australians will be the first generation to use nicotine at higher rates than previous generations, thereby undoing decades of effective tobacco control.

TRIAL REGISTRATION

The trial has been prospectively registered with the Australian and New Zealand Clinical Trials Registry (ACTRN12623000022662; date registered: 10/01/2023).

Impact of tobacco smoke constituents on nicotine-seeking behavior in adolescent and adult male rats

INTRODUCTION

Given the rapid increase in teen vaping over recent years it is critical to understand mechanisms underlying addiction and relapse to tobacco use at this age. To evaluate the role of non-nicotine constituents in cigarette smoke, our lab has previously established a model of intravenous self-administration of aqueous cigarette smoke extract (CSE). We now compare the sensitivity of male adolescent and adult rats who have self-administered CSE or nicotine to reinstatement with the pharmacological stressor, yohimbine, with and without cues.

METHODS

Adolescents and adults, aged postnatal day (P) 34 and 84, were tested for the effect of yohimbine (0-2.5 mg/kg) on plasma corticosterone levels to establish a dose that was an effective stressor at both ages. Separate groups of animals were trained to lever press for food before beginning 1-hour drug self-administration sessions for nicotine or CSE (15 μg/kg/infusion nicotine content). Once stable responding was reached, drug was removed, and behavior extinguished. Drug-seeking behavior was reinstated with yohimbine, cues, or a combination of yohimbine and cues.

RESULTS

Although adolescents and adults showed different dose-responses for yohimbine-induced corticosterone release, a dose of 2.5 mg/kg increased stress hormone levels at both ages. Whereas both ages displayed similar responding for CSE and nicotine, adolescents self-administered more CSE and nicotine as compared to adults. Cues and cues + stress reinstated responding to a greater extent in animals that had self-administered CSE, regardless of age.

DISCUSSION

These findings suggest that non-nicotine tobacco smoke constituents influence later but not earlier stages of addiction in both adolescent and adult male rats.

E-cigarette addiction and harm perception: Does initiation flavor choice matter?

Introduction

The 21^st century was marked by a dramatic increase in adolescent e-cigarette use in the United States (US). The popularity of non-traditional flavor types, including fruit and pastry, is thought to contribute toward growing product use nationally, leading to a variety of federal and state regulations limiting the use of non-traditional flavors in the US. The relationship between flavor type and increased adolescent use suggests a possible link between flavor use and addiction and harm perception. This study assessed if the flavor type used when initiating e-cigarette use predicted addiction and harm perceptions.

Methods

The study utilized data from the multi-wave youth Population Assessment of Tobacco Health Study. It explored the impact initiating e-cigarette use with traditional versus non-traditional flavor types among cigarette users on the outcome variables: e-cigarette addiction and harm perception. Both e-cigarette addiction and harm perception were measured using self-report, Likert scale questionnaires. Descriptive statistics characterized the study variables and linear regression analyses performed to test whether flavor initiation type is associated with addiction and harm perception.

Results

The study sample consisted of 1,043 youth (weighted N = 1,873,617) aged 12 to 17 years who reported at least one instance of e-cigarette use. After adjusting for age, age of onset, sex, race and annual household income there was no statistically significant difference in addiction levels between those initiating with traditional versus non-traditional flavors (p = 0.294). Similarly, traditional versus non-traditional flavor initiation did not show a statistically significant difference in adolescent e-cigarette harm perceptions (p = 0.601).

Conclusions

Traditionally flavored e-cigarette initiation produces similar risk for addiction and harm perceptions as non-traditionally flavored initiation. These findings suggest that banning non-traditional flavors alone may be ineffective in curbing e-cigarette addiction and harm perception. Additional research is needed to better understand which e-cigarette product characteristics and behaviors may be associated with greater addiction and reduced harm perceptions.

Nicotine dependence of cigarette and heated tobacco users in Japan, 2019: a cross-sectional analysis of the JASTIS Study

OBJECTIVES

Japan is currently the biggest market of heated tobacco products (HTPs) in the world. Little is known about nicotine dependence among HTP users. Thus, the objective was to assess the association of type of tobacco use and time-to-first-use, a marker of nicotine dependence.

METHODS

A cross-sectional analysis of the 2019 data from an internet cohort study was conducted. The analytical sample consisted of 2147 current (≥1 day use in the past 30 days) HTP and/or conventional cigarette users, aged 25+ years. Marginal structural binomial regression was used to estimate nicotine dependence prevalence ratios (PRs) for each category of tobacco use (exclusive daily cigarette, exclusive HTP (≥1 day), dual HTP+daily cigarette, dual HTP+non-daily cigarette), relative to exclusive, non-daily cigarette smoking.

RESULTS

Using a 5 min cut-off for time-to-first-use, the prevalence of nicotine dependence was higher among dual users of HTP and daily cigarettes (PR=1.38; 95% CI: 1.05 to 1.82) and exclusive, daily cigarette users (PR=1.48; 95% CI: 1.15 to 1.91), relative to exclusive, non-daily cigarette users. However, nicotine dependence among exclusive HTP users, and dual HTP+non-daily cigarette users, did not differ from that of exclusive, non-daily cigarette users. When using 15 and 30 min cut-offs, all types of users, including exclusive HTP, had higher levels of nicotine dependence relative to exclusive, non-daily cigarette users.

CONCLUSIONS

Regardless of HTP use, daily cigarette users had higher prevalence of nicotine dependence compared with non-daily cigarette users. Exclusive HTP users had similar (or potentially higher) dependence compared with exclusive, non-daily cigarette users. Longitudinal studies are needed to interrogate the public health implications of growing HTP use worldwide.

Systematic review on e-cigarette and its effects on weight gain and adipocytes

Smoking and obesity are leading causes of morbidity and mortality worldwide. E-cigarette which was first introduced in 2000s is perceived as an effective alternative to conventional tobacco smoking. Limited knowledge is available regarding the risks and benefits of e-cigarettes. This study systematically reviews the current literature on the effects of e-cigarettes on body weight changes and adipocytes. The search was performed using OVID Medline and Scopus databases and studies meeting the inclusion criteria were independently assessed. This review included all English language, empirical quantitative and qualitative papers that investigated the effects of e-cigarettes on bodyweight or lipid accumulation or adipocytes. Literature searches identified 4965 references. After removing duplicates and screening for eligibility, thirteen references which involve human, in vivo and in vitro studies were reviewed and appraised. High prevalence of e-cigarette was reported in majority of the cross sectional studies conducted among respondent who are obese or overweight. More conclusive findings were identified in in vivo studies with e-cigarette causing weight decrease. However, these observations were not supported by in vitro data. Hence, the effect of e-cigarette on body weight changes warrants further investigations. Well-designed population and molecular studies are needed to further elucidate the role of e-cigarettes in obesity.

Effects of mango and mint pod-based e-cigarette aerosol inhalation on inflammatory states of the brain, lung, heart, and colon in mice

While health effects of conventional tobacco are well defined, data on vaping devices, including one of the most popular e-cigarettes which have high nicotine levels, are less established. Prior acute e-cigarette studies have demonstrated inflammatory and cardiopulmonary physiology changes while chronic studies have demonstrated extra-pulmonary effects, including neurotransmitter alterations in reward pathways. In this study we investigated the impact of inhalation of aerosols produced from pod-based, flavored e-cigarettes (JUUL) aerosols three times daily for 3 months on inflammatory markers in the brain, lung, heart, and colon. JUUL aerosol exposure induced upregulation of cytokine and chemokine gene expression and increased HMGB1 and RAGE in the nucleus accumbens in the central nervous system. Inflammatory gene expression increased in the colon, while gene expression was more broadly altered by e-cigarette aerosol inhalation in the lung. Cardiopulmonary inflammatory responses to acute lung injury with lipopolysaccharide were exacerbated in the heart. Flavor-specific findings were detected across these studies. Our findings suggest that daily e-cigarette use may cause neuroinflammation, which may contribute to behavioral changes and mood disorders. In addition, e-cigarette use may cause gut inflammation, which has been tied to poor systemic health, and cardiac inflammation, which leads to cardiovascular disease.

Cue Reactivity to Electronic Cigarettes: A Systematic Review

Cue reactivity to Electronic Nicotine Delivery Systems (ENDS) has been studied by several researchers, yet the variability in user types (smokers, former smokers, dual users, exclusive ENDS users) and ENDS designs used between the studies may have undermined consistent results. This systematic review aims to give an overview of ENDS cue reactivity and how smoking status and device design may moderate this. A systematic search of Medline, Embase, Web of Science, PubMed and Cochrane was completed. All studies which reported findings on reactivity to ENDS cues in the form of craving or desire for ENDS or cigarettes, attention to cue, delay of gratification or economic decisions were included. Exclusion criteria were non-human subjects, non-adult participants or participants with comorbidities. Literature selection was carried out by 2 independent reviewers. The risk of bias and study quality were assessed using tools developed by Cochrane, BMJ and NHLBI. A total of 711 papers were screened and 22 studies were included in the current review. Study design, research question(s), population of interest, number of participants, dependent variable(s), ENDS generation and nicotine content used and study results were extracted. ENDS cues reliably induced ENDS craving, with no clear moderation by smoking status and no apparent moderation by device generation. In about half of the studies, ENDS cues induced craving for conventional cigarettes. Most studies used a smoker sample, thus limiting the conclusions that can be drawn on the moderation of cue reactivity by smoking status. The quality varied among studies but comparing the findings against the outcomes of only high-quality studies did not yield any different results. The results of this review support the notion of cue reactivity to ENDS, identifies gaps in current research on different user types and implies that ENDS design iterations have little impact on cue reactivity.

E-cigarettes use among university students in Jordan: Perception and related knowledge

The use of e-cigarettes has been increasing in popularity among people, especially young adults. Assessing young individuals’ perceptions of e-cigarettes can help to identify factors that may influence their decision to use e-cigarettes. To examine prevalence, perceptions, and knowledge of e-cigarettes among university students in Jordan, an observational cross-sectional study using an online self-administered questionnaire was conducted among students from public and private universities between October 2020 and January 2021. A total of 1259 university students completed the questionnaire. Approximately, 11% of participants reported e-cigarettes use. Among users, 26.5% used it for the purpose of smoking cessation, while 22% of them used it out of curiosity, and 20.5% used it as they believed it is less harmful than other tobacco products. Multivariate analysis showed that conventional cigarette smokers were independently associated with a better knowledge about e-cigarettes (OR = 1.496, 95CI% = 1.018–2.197, p-value = 0.040). In addition, medical students showed a significantly better knowledge compared to non-medical students (OR = 1.710, 95CI% = 1.326–2.204, p-value = <0.001). In Jordan, e-cigarettes use is less popular compared to other countries. Nonetheless, educational interventions are needed to correct misconceptions about e-cigarettes among young adults.

Nicotine dependence symptoms in U.S. youth who use JUUL E-cigarettes

PURPOSE

To estimate the prevalence, patterns, and correlates of self-reported nicotine dependence symptoms among U.S. youth who use JUUL - a widely-sold e-cigarette brand - in 2019 and compare findings to nicotine dependence symptoms in youth who smoke cigarettes.

METHODS

Data were from a nationally-representative subsample of 8th, 10th, and 12th grade students in the Monitoring the Future Study who had used JUUL or cigarettes in the past 30 days. Participants self-reported presence/absence of 9 different nicotine dependence symptoms for JUUL or cigarettes. Weighted percentages for JUUL or cigarette nicotine dependence symptom status (≥1 vs. 0 symptoms) and severity (count, range: 0-9) were calculated. Among JUUL users, we estimated associations of sociodemographic characteristics and other substance use with nicotine dependence and severity.

RESULTS

Among 1,748 past 30-day JUUL users, 41.3 % screened positive for ≥1 nicotine dependence symptoms; the mean symptom count was 1.6 (SD = 2.6). Non-nicotine substance use and more frequent JUUL use was associated with significantly greater odds of dependence and more severe dependence symptoms in multivariable models. The severity distribution of most (craving) and least (inability to quit) dependence symptom types observed in JUUL dependence paralleled those observed in analysis of combustible cigarette dependence symptoms in past 30-day smokers.

CONCLUSION

A substantial proportion of U.S. adolescent JUUL users reported symptoms of nicotine dependence, which is greater for those who vape more frequently and use other substances. Nicotine dependence screening, prevention, and regulatory policies addressing use of JUUL or similar e-cigarette products should be considered to protect U.S. youth.

Comparison of e-cigarette use prevalence and frequency by smoking status among youth in the United States, 2014-19

BACKGROUND AND AIMS

Reports of youth e-cigarette use often do not disaggregate by underlying smoking status. This study compared annual 2014-19 youth estimates of past 30-day e-cigarette use prevalence and frequency by smoking status in the United States.

DESIGN

Nationally representative, cross-sectional, school-based survey [National Youth Tobacco Surveys (NYTS)]. General linear models accounting for complex survey design compared e-cigarette use prevalence by smoking status by year, overall and stratified by frequency, separately for high school (HS) and middle school (MS) students. The 2019 survey was analyzed separately because of its change in survey methodology.

SETTING

MSs and HSs in the United States.

PARTICIPANTS

A total of 116 704 students from 1268 schools, ages 9-19.

MEASUREMENTS

Students self-reported (paper 2014-18, electronic 2019) ever and past 30-day (current) use of e-cigarettes and cigarettes, as well as frequent use (20-30 days of month).

FINDINGS

From 2014 to 2018, current e-cigarette use prevalence increased among never, current and former smokers in HS, but only among never and current smokers in MS (each P-value < 0.001). E-cigarette use increases for current HS smokers were primarily among frequent e-cigarette users. In 2018, the absolute number of HS frequent users who were never or former smokers (420 000 combined) surpassed current smokers (370 000). In 2019, current e-cigarette use prevalence for never, former and current smokers was 17.5% [95% confidence interval (CI) = 16.0-19.0], 53.6% (95% CI = 45.2-61.9) and 85.8% (95% CI = 81.6-89.9) for HS students, respectively, and 6.8% (95% CI = 5.9-7.7), 40.8% (95% CI = 34.7-47.0) and 78.0% (95% CI = 71.9-84.2) for MS students. That year, the number of HS never (420 000) and former smokers (570 000) using e-cigarettes frequently eclipsed that of current smokers (390 000).

CONCLUSIONS

E-cigarette use prevalence and frequency among youth vary by smoking status, with highest levels of use among current smokers. However frequent e-cigarette use among never smokers and former smokers has increased.

Youth use of e-cigarettes: Does dependence vary by device type?

INTRODUCTION

Youth nicotine dependence may vary by e-cigarette device used.

METHODS

E-cigarette device type ("JUUL," "similar pod/JUUL like device (i.e., pod mod)," or "other type of e-cigarette" (i.e., tank, mod)), nicotine dependence (Hooked on Nicotine Checklist; HONC), frequency of e-cigarette use (i.e., weekly, daily, monthly), and covariates were examined via a convenience sample of youth who use e-cigarettes in the United States via an online Qualtrics panel survey from April 2019 to May 2019.

RESULTS

Youth aged 13-17 (Mean age = 15.9 years, SD = 1.0 year; n = 185) were mostly 72.4% female. Primary device used by category was endorsed as follows: JUUL n = 87, pod mod n = 42, and other type of e-cigarette n = 56. Participants endorsed an average of 4.5 / 10 HONC symptoms (SD = 3.6). Compared to other e-cigarettes, youth who used JUUL and pod mod devices endorsed more dependence symptoms, even when adjusting for current smoking status (JUUL IRR = 1.96, 95% CI 1.30-2.97; pod mod device IRR = 1.76, 95% CI 1.08-2.87). In total, HONC symptoms significantly differed by device for 8/10 symptoms, with JUUL and pod mod users reporting higher frequency of items compared to other e-cigarette devices.

CONCLUSIONS

Features of nicotine dependence experienced by youth (i.e., feeling a stronger urge to vape) differed by primary device used, with those using JUUL and pod-mods reporting a greater level of dependence. Regulation of features of e-cigarette devices that may increase nicotine delivery and subsequent development of dependence among youth warrant urgent consideration.

Real-world vaping experiences and smoking cessation among cigarette smoking adults

INTRODUCTION

E-cigarettes may have the potential to be an effective cessation aid for some cigarette smokers. However, the extent to which smokers' experiences using e-cigarettes (vaping) to quit smoking impact their cessation outcomes is unclear. In this cross-sectional survey study, we develop a multidimensional measure of vaping experiences in adults who quit smoking by vaping and test its association with perceived success in smoking cessation.

METHODS

In 2019, recruitment invitations were emailed to adult past-year smokers who had accessed cessation services across Ontario, Canada. Respondents who tried vaping to quit smoking in the past year completed a detailed online survey. Factor analysis was performed on ratings of 45 vaping experiences items to identify dimensions of vaping experiences. Factor scores were entered into logistic regressions to test if vaping experiences dimensions had differential impact on perceived success in smoking cessation.

RESULTS

Of the 889 participants, 56.0% were female, 81.1% were Caucasian, and the mean age was 37.7 ± 11.9 years. Twenty percent (19.6%) reported having successfully quit smoking by vaping in the past year. Among the six vaping experiences factors, better experiences in five factors-Relationships, Flexibility of Vaping, Side Effects, Vaping Devices, and Sensory Functions-were each independently and positively associated with improved odds of successful quitting. Notably, Relationships [OR = 2.01, 95% CI: 1.61-2.64] and Side Effects [OR = 1.95; 95% CI 1.54-2.29] were the strongest correlates of perceived success in smoking cessation.

CONCLUSIONS

These findings indicate an opportunity to increase cessation rates by improving the experiences of smokers who vape to quit smoking.

Nicotine Dependence Evaluated by Urinary Cotinine and Heaviness of Smoking Index among Smokers, Vapers, and Dual Users: A Cross-Sectional Study Using the Korea National Health and Nutrition Examination Survey Data

BACKGROUND

Many people use both combustible cigarette (CC) and electronic cigarette (EC). We compared nicotine dependence among CC, EC, and dual users using questionnaires and urinary cotinine levels.

METHODS

Data from the Korea National Health and Nutrition Examination Survey (2014-2017) databases were analyzed; 3,917 CC, EC, and dual users were administered the urinary cotinine test, and 1,045 current CC and dual users completed the Heaviness of Smoking Index (HSI) questionnaires. Weighted geometric means of urine cotinine levels were compared between exclusive CC, exclusive EC, and dual users. The distribution rate, based on time to first cigarette (TTFC), cigarettes per day (CPD), and the HSI was analyzed in two weighted groups, exclusive CC and dual users.

RESULTS

Among those who currently use any type of cigarette, 89.4%, 1.4%, and 9.2% were exclusive CC, exclusive EC, and dual users, respectively. Weighted geometric means of urine cotinine were highest in dual users (1,356.4 ng/mL), followed by exclusive CC (1,270.3 ng/mL), and exclusive EC (867.7 ng/mL) with significant differences between all three groups (P<0.05). There were no statistically significant differences in CPD between exclusive CC and dual users (P=0.626). The proportion of TTFC ≤5 minutes was 21.5% and 29.5% in the two groups, respectively (P=0.010); however, HSI differences in the two groups was marginal (P=0.557).

CONCLUSION

In this study, the urinary cotinine value could distinguish the three groups, CC, EC, and dual users, but the questionnaire using HSI could not distinguish the three groups.

Machine Learning-Based Nicotine Addiction Prediction Models for Youth E-Cigarette and Waterpipe (Hookah) Users

Despite the harmful effect on health, e-cigarette and hookah smoking in youth in the U.S. has increased. Developing tailored e-cigarette and hookah cessation programs for youth is imperative. The aim of this study was to identify predictor variables such as social, mental, and environmental determinants that cause nicotine addiction in youth e-cigarette or hookah users and build nicotine addiction prediction models using machine learning algorithms. A total of 6511 participants were identified as ever having used e-cigarettes or hookah from the National Youth Tobacco Survey (2019) datasets. Prediction models were built by Random Forest with ReliefF and Least Absolute Shrinkage and Selection Operator (LASSO). ReliefF identified important predictor variables, and the Davies–Bouldin clustering evaluation index selected the optimal number of predictors for Random Forest. A total of 193 predictor variables were included in the final analysis. Performance of prediction models was measured by Root Mean Square Error (RMSE) and Confusion Matrix. The results suggested high performance of prediction. Identified predictor variables were aligned with previous research. The noble predictors found, such as ‘witnessed e-cigarette use in their household’ and ‘perception of their tobacco use’, could be used in public awareness or targeted e-cigarette and hookah youth education and for policymakers.

Indicators of dependence and efforts to quit vaping and smoking among youth in Canada, England and the USA

OBJECTIVE

The current study examined indicators of dependence among youth cigarette smokers and e-cigarette users in Canada, England and the USA, including changes between 2017 and 2019.

METHODS

Data are from repeated cross-sectional online surveys conducted in 2017, 2018 and 2019 with national samples of youth aged 16-19 years, in Canada (n=12 018), England (n=11 362) and the USA (n=12 110). Measures included perceived addiction to cigarettes/e-cigarettes, frequency of experiencing strong urges to smoke/use an e-cigarette, plans to quit smoking/using e-cigarettes and past attempts to quit. Logistic regression models were fitted to examine differences between countries and changes over time.

RESULTS

The proportion of ever-users who vaped frequently was significantly higher in 2019 compared with 2017 for all outcomes in each country. Between 2017 and 2019, the proportion of past 30-day vapers reporting strong urges to vape on most days or more often increased in each country (Canada: 35.3%, adjusted OR (AOR) 1.69, 95% CI 1.20 to 2.38; England: 32.8%, AOR 1.55, 1.08 to 2.23; USA: 46.1%, AOR 1.88, 1.41 to 2.50), along with perceptions of being 'a little' or 'very addicted' to e-cigarettes (Canada: 48.3%, AOR 1.99, 1.44 to 2.75; England: 40.1%, AOR 1.44, 1.03 to 2.01; USA: 53.1%, AOR 1.99, 1.50 to 2.63). Indicators of dependence among smokers were consistently greater than e-cigarette users, although differences had narrowed by 2019, particularly in Canada and the USA.

CONCLUSIONS

Prevalence of dependence symptoms among young e-cigarette users increased between 2017 and 2019, more so in Canada and the USA compared with England. Dependence symptom prevalence was lower for e-cigarettes than smoking; however, the gap has narrowed over time.

Treatment of Adolescent e-Cigarette Use: Limitations of Existing Nicotine Use Disorder Treatment and Future Directions for e-Cigarette Use Cessation

Electronic cigarette use ("vaping") has surged in the United States since the mid-2010s. From 2011 to 2018, current e-cigarette use among high school students escalated from 1.5% to 20.8% (∼3.05 million youths),¹ countering downward trends in combustible nicotine product use (21.8% in 2011 to 13.9% in 2018).¹ Although preventing the initial uptake of vaping is crucial, for the millions of adolescents who have taken up this behavior-many of whom express interest in quitting (eg, 44.5% of current, adolescent non-light e-cigarette users in one US national representative sample)²-it is critically important to help them quit vaping so as to curtail future substance use disorders and other health consequences. Here, we discuss several challenges around adolescent vaping treatment, and highlight research areas in urgent need of attention.

Electronic Cigarette Use Among Youth: Understanding Unique Risks in a Vulnerable Population

PURPOSE OF REVIEW

This review discusses prevalence rates of electronic (e-)cigarette use among youth and factors that likely contribute to their growing popularity among this population. Trends shaping the e-cigarette landscape, the appeal of e-cigarettes among youth, perceptions contributing to the initiation of e-cigarettes, available assessments capturing the usage of and attitudes towards e-cigarettes, and e-cigarette policies and regulations are reviewed.

RECENT FINDINGS

E-cigarette use among this vulnerable group may relate to factors associated with the promotion of social status, individuality, and enjoyment, along with low perceptions of risk and harm. Measures assessing factors unique to e-cigarette use among youth (e.g., individuality) still need to be developed and validated. Effects of existing regulations to limit youth access to e-cigarettes may be limited, and shortcomings of current policy measures are discussed with recommendations.

SUMMARY

The rise of e-cigarette use among youth culminated through a perfect storm of clever marketing targeting youth appeal, innovations in more effective nicotine delivery systems, capitalizing on increased susceptibility of the adolescent brain, and regulatory gaps. Understanding risk and protective factors specific to this vulnerable group, which can be gleaned in part by psychometrically valid assessments, could inform regulatory strategies and prevention programming efforts. Yet, few validated measures exist that assess attitudes, behaviors, and patterns of e-cigarette use that are specific to youth. Ultimately, it is incumbent upon policymakers to create comprehensive regulations that prioritize harm reduction and can evolve in lockstep with the constantly changing e-cigarette product landscape.

Patterns of tobacco use and nicotine dependence among youth, United States, 2017-2018

This study examined patterns of tobacco product use and their association with nicotine dependence among U.S. youth. Combined data from the 2017-2018 National Youth Tobacco Surveys were analyzed for students that reported current (past-30-day) use of e-cigarettes, cigarettes, cigars, smokeless tobacco, or hookah (n = 6106). Analyses assessed multiple product use (≥2 tobacco products) overall and by sex, school level, race/ethnicity, current use, and frequent use (use of a product for ≥20 of the preceding 30 days). Multivariable logistic regression was used to identify correlates of nicotine dependence. During 2017-2018, 40.8% of tobacco product users reported use of multiple products. Multiple product use ranged from 47.0% among e-cigarette users to 80.7% among cigarette smokers. Among frequent users of each respective product, 80.0% of cigarette smokers, 74.9% of cigar smokers, 73.6% of smokeless tobacco users, 70.7% of hookah smokers, and 40.3% of e-cigarette users reported use of multiple products. Most youth who reported nicotine dependence (64.0%) were multiple product users. E-cigarettes were the most common single product used (36.3%) and the product most commonly used in combination with other products; e-cigarettes plus cigarettes (6.7%) was the most common product combination. Combustible product use, smokeless tobacco use, multiple product use and frequent use were associated with greater odds of nicotine dependence. Nicotine dependence among youth is especially influenced by cigarette use, smokeless tobacco use, frequent use of any tobacco product, and multiple product use. Proven tobacco control interventions in coordination with regulatory efforts can reduce youth tobacco product use.

An update on controversies in e-cigarettes

E-cigarettes are electronic nicotine delivery systems (ENDS) which mimic tobacco smoking without the combustion of tobacco. These devices have been misleadingly marketed as "less harmful" alternatives to conventional smoking tobacco products. The e-liquid in e-cigarettes include nicotine, a humectant and other additives including flavourings, colourants, or adulterants such as bacterial and fungal products. In this review, we discuss the contrasting views of the tobacco lobby and most professional societies. We describe the epidemiology of the use of these devices, with a widespread and significant rise in youth e-cigarette use seen in both the USA and Europe. We also describe what is known about the toxicity and mechanisms of EVALI (e-cigarette or vaping associated lung injury). This characterised by respiratory failure with an intense inflammatory response. The presentations are diverse and clinicians should consider vaping as a possible cause of any unusual respiratory illness in patients who have a history of vaping or other use of e-cigarette-related products. Second hand exposure to e-cigarettes is also harmful through respiration and transdermal absorption. E-cigarettes have a worse acute toxicity than tobacco and their long-term toxicity is unknown, and we advocate for the immediate, most vigorous anti-vaping legislation possible.

Effects of 3-Month Exposure to E-Cigarette Aerosols on Glutamatergic Receptors and Transporters in Mesolimbic Brain Regions of Female C57BL/6 Mice

Electronic cigarettes (e-cigs) use has been dramatically increased recently, especially among youths. Previous studies from our laboratory showed that chronic exposure to e-cigs, containing 24 mg/mL nicotine, was associated with dysregulation of glutamate transporters and neurotransmitter levels in the brain of a mouse model. In this study, we evaluated the effect of three months’ continuous exposure to e-cig vapor (JUUL pods), containing a high nicotine concentration, on the expression of glutamate receptors and transporters in drug reward brain regions such as the nucleus accumbens (NAc) core (NAc-core), NAc shell (NAc-shell) and hippocampus (HIP) in female C57BL/6 mice. Three months’ exposure to mint- or mango-flavored JUUL (containing 5% nicotine, 59 mg/mL) induced upregulation of metabotropic glutamate receptor 1 (mGluR1) and postsynaptic density protein 95 (phosphorylated and total PSD95) expression, and downregulation of mGluR5 and glutamate transporter 1 (GLT-1) in the NAc-shell. In addition, three months’ exposure to JUUL was associated with upregulation of mGluR5 and GLT-1 expression in the HIP. These findings demonstrated that three-month exposure to e-cig vapor containing high nicotine concentrations induced differential effects on the glutamatergic system in the NAc and HIP, suggesting dysregulation of glutamatergic system activity in mesolimbic brain regions.

Sponsorship Disclosures and Perceptions of E-cigarette Instagram Posts

OBJECTIVES

Instagram influencers have many followers and are often paid to promote products, including e-cigarettes. This experimental study assessed effects of sponsorship disclosures on perceptions of e-cigarette Instagram influencer posts.

METHODS

Young adult e-cigarette users (age 18-29; N = 917) were randomly assigned to 3 experimental conditions varying the clarity of sponsorship disclosure on simulated Instagram influencer posts: clear (eg, "#sponsored") ambiguous (eg, "#sp"), or no disclosure (ie, vaping-related hashtags only). After viewing each of 4 Instagram posts featuring a fictitious e-cigarette brand, participants reported hashtag recognition, ad recognition, ad trust, influencer credibility, and post engagement intentions. After viewing all posts, participants reported brand attitudes, brand use intentions, and vaping intentions.

RESULTS

With greater recognition of clear (but not ambiguous) disclosure hashtags, ad recognition increased (p = .001), perceptions of influencer credibility decreased (p = .022), and intentions to engage with posts decreased (p = .008). Ad trust was lower with greater hashtag recognition regardless of disclosures (p < .001). Sponsorship disclosures did not significantly affect brand attitudes, brand use intentions, or vaping intentions.

CONCLUSIONS

Recognizing clear sponsorship disclosures may influence young adults' perceptions of and engagement with e-cigarette Instagram posts but may not affect perceptions or use of products.

Perceived addiction to vaping among youth and young adult regular vapers

BACKGROUND

The prevalence of e-cigarette use among youth and young adults has increased markedly in recent years; however, little is known about young people's perceptions of e-cigarette addiction. This study examines factors associated with self-reported addiction to e-cigarette use among this population.

METHODS

In 2018, 1048 Canadians aged 16-25 years were recruited through online social media platforms to complete a survey. Quota sampling was used to oversample regular e-cigarette users (vaping at least weekly); these 578 regular users were included in this analysis. Self-perceived addiction was assessed by asking participants if they felt they were 'very', 'somewhat' or 'not at all' addicted to e-cigarettes. A proportional odds model was employed to identify factors associated with the ordinal outcome.

RESULTS

Almost half of regular users perceived themselves to be 'not at all addicted', 41% felt they were 'somewhat addicted' and 13% felt they were very addicted to e-cigarettes. Women, former cigarette smokers, daily vapers and those vaping for more than a year were more likely to report higher levels of perceived addiction. Similarly, high sensation-seeking youth, those reading blogs and websites about vaping, those frequently dripping and those using higher nicotine strengths had a greater likelihood of higher perceived addiction than their respective counterparts.

CONCLUSION

More than half of youth and young adult regular e-cigarette users felt they had some level of addiction. The findings identify possible opportunities for targeted programming for education and treatment, as well as potential opportunities for policy change such as maximum allowable nicotine strengths.

The Effects of Nicotine on Development

Recently, there has been a significant increase in the use of noncombustible nicotine-containing products, including electronic cigarettes (e-cigarettes). Of increasing popularity are e-cigarettes that can deliver high doses of nicotine over short periods of time. These devices have led to a rise in nicotine addiction in adolescent users who were nonsmokers. Use of noncombustible nicotine products by pregnant mothers is also increasing and can expose the developing fetus to nicotine, a known teratogen. In addition, young children are frequently exposed to secondhand and thirdhand nicotine aerosols generated by e-cigarettes, with little understanding of the effects these exposures can have on health. With the advent of these new nicotine-delivery systems, many concerns have arisen regarding the short- and long-term health effects of nicotine on childhood health during all stages of development. Although health studies on nicotine exposure alone are limited, educating policy makers and health care providers on the potential health effects of noncombustible nicotine is needed because public acceptance of these products has become so widespread. Most studies evaluating the effects of nicotine on health have been undertaken in the context of smoke exposure. Nevertheless, in vitro and in vivo preclinical studies strongly indicate that nicotine exposure alone can adversely affect the nervous, respiratory, immune, and cardiovascular systems, particularly when exposure occurs during critical developmental periods. In this review, we have included both preclinical and clinical studies to identify age-related health effects of nicotine exposure alone, examining the mechanisms underlying these effects.

Prevalence of Electronic Cigarette Dependence Among Youth and Its Association With Future Use

IMPORTANCE

Understanding the prevalence and symptoms of electronic cigarette (e-cigarette) dependence and its association with future e-cigarette use among youth may help to guide pediatric clinical services and health policy.

OBJECTIVES

To examine the cross-sectional prevalence and symptom presentation of e-cigarette dependence and to determine whether e-cigarette dependence is associated with subsequent e-cigarette use patterns 6 months later among youth with baseline past-year e-cigarette use.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study used baseline and 6-month follow-up surveys among students in the 12th grade during the 2016 to 2017 school year who reported any past-year e-cigarette use. Surveys were conducted on site in 10 high schools in Los Angeles, California. Data were analyzed from March 2019 to December 2019.

MAIN OUTCOMES AND MEASURES

Self-reported checklist of 10 tobacco product dependence symptoms reflecting loss of control over use, craving or urge, or withdrawal symptoms while abstinent, completed at baseline and administered separately for e-cigarettes and combustible cigarettes. Reporting 1 or more symptoms indicated a positive screen for dependence. Vaping continuation, defined as any past 6-month vaping, and past 30-day nicotine vaping days (range, 0-30), sessions per vaping day (range, 0-20), and puffs per session (range, 0-20) at 6-month follow-up were assessed.

RESULTS

Among 3168 twelfth-grade students who completed the baseline survey, 444 youths (mean [SD] age, 17.48 [0.39] years; 217 [48.9%] female) reported past-year e-cigarette use. Among these, 52 youths (11.7%) reported at least 1 e-cigarette dependence symptom. Among youth who reported past-year dual e-cigarette and combustible cigarette use, combustible cigarette dependence, reported by 43 youths (29.7%), was more prevalent than e-cigarette dependence, which was reported by 24 youths (16.4%). The most common symptoms, craving, urge, and need to use, and least common symptoms, abstinence-related concentration and emotional problems, were similar in both combustible and e-cigarette dependence. The prevalence of e-cigarette dependence was higher among youth who reported vaping in the past month than among those who did not (41 youths [17.6%] vs 11 youths [5.2%]; P < .001) and among youth who used e-cigarettes with nicotine than among those who used e-cigarettes without nicotine (42 youths [15.2%] vs 10 youths [6.0%]; P = .004). After adjusting for baseline vaping and e-cigarette dependence risk propensity scores, baseline e-cigarette dependence symptom status was associated with vaping continuation (adjusted odds ratio, 2.30 [95% CI, 1.07-4.94]; P = .02) and past 30-day number of nicotine vaping days (adjusted rate ratio, 2.17 [95% CI, 1.44-3.28]; P < .001), vaping sessions per day (adjusted rate ratio, 2.41 [95% CI, 1.52-3.83]; P < .001), and puffs per session (adjusted rate ratio, 1.70 [95% CI, 1.09-2.66]; P = .02) at 6-month follow-up.

CONCLUSIONS AND RELEVANCE

These findings suggest that e-cigarette dependence may be an expression of tobacco use disorder associated with future use persistence and escalation among youth. Electronic cigarette dependence may be a behavioral health consequence of adolescent vaping that warrants consideration in pediatric patient care and public health policy.

Current advances in research in treatment and recovery: Nicotine addiction

The health harms of combusted tobacco use are undeniable. With market and regulatory pressures to reduce the harms of nicotine delivery by combustion, the tobacco product landscape has diversified to include smokeless, heated, and electronic nicotine vaping products. Products of tobacco combustion are the main cause of smoking-induced disease, and nicotine addiction sustains tobacco use. An understanding of the biology and clinical features of nicotine addiction and the conditioning of behavior that occurs via stimuli paired with frequent nicotine dosing, as with a smoked cigarette, is important for informing pharmacologic and behavioral treatment targets. We review current advances in research on nicotine addiction treatment and recovery, with a focus on conventional combustible cigarette use. Our review covers evidence-based methods to treat smoking in adults and policy approaches to prevent nicotine product initiation in youth. In closing, we discuss emerging areas of evidence and consider new directions for advancing the field.

Adolescents' E-Cigarette Use: Increases in Frequency, Dependence, and Nicotine Exposure Over 12 Months

PURPOSE

This study examined changes in e-cigarette and dual-use frequency, levels of nicotine exposure and e-cigarette dependence, and device and e-liquid preferences over 12 months.

METHODS

Adolescents (N = 173, aged 13-18 years) who reported past-month e-cigarette use and at least 10 lifetime uses were recruited from the San Francisco Bay Area. The sample was 75.1% male, 54.9% non-Hispanic White, mean age 16.6 years (standard deviation = 1.2); 26.6% reported past-month cigarette smoking at baseline (i.e., dual use). At baseline, 6-month, and 12-month follow-up, participants provided saliva samples for cotinine testing and self-reported e-cigarette use frequency, dependence, past-month smoking, product preference, and flavor preference.

RESULTS

Most (80.3%) were still using e-cigarettes at 12 months, and daily use increased from 14.5% to 29.8%. Model testing indicated an overall increase from baseline to 12 months in frequency of e-cigarette use (F(2, 166) = 5.69, p = .004), dependence (F(2, 164) = 5.49, p = .005), and cotinine levels (F(2, 103) = 4.40, p = .038). Among those reporting only e-cigarette use at baseline, 28.8% reported combustible cigarette use during follow-up. Among those reporting dual use at baseline, 57.1% were still dual using at 12 months, 31.4% reported e-cigarette use only, and none abstained from both products. Higher nicotine delivering e-cigarette devices (i.e., Juul, mods) became more popular over time, whereas flavor preferences (i.e., fruit, mint/menthol, and candy) remained stable.

CONCLUSIONS

Adolescents' e-cigarette use persisted over a 12-month period with significant increases in frequency of use, nicotine exposure, and e-cigarette dependence. Transitions from single to dual and dual to single nicotine product use were observed in approximately one in three users over the study period.