The role of E-liquid vegetable glycerin and exhaled aerosol on cue reactivity to tank-based electronic nicotine delivery systems (ENDS)

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.

Cue Reactivity Effects of Heated Tobacco Product Use in Current, Former, and Never Smokers in the United States

INTRODUCTION

Heated tobacco products (HTPs) share similar characteristics as combustible cigarettes and electronic nicotine delivery systems (ENDS) and thus may serve as cues for smoking and vaping. While HTP familiarity is low in the United States, HTPs may be perceived as a less harmful alternative to cigarettes.

AIMS AND METHODS

The present study examined if visual exposure to HTP use influenced cigarette and e-cigarette craving in a large national sample of adults with varied smoking patterns. Current, former, and never cigarette smokers (N = 515; Mage = 40) were recruited from online crowd-sourcing panels throughout the United States from January to April 2020. Participants completed surveys before and after watching a video depicting the use of an HTP, cigarette, or bottled water. Main outcomes were changes in cigarette craving after exposure to the video cue. Secondary outcomes included changes in e-cigarette craving.

RESULTS

Relative to the water cue, the HTP and cigarette cues increased cigarette craving in current smokers. The HTP cue also increased e-cigarette craving (desire for a mod or vape pen and JUUL) across all subgroups.

CONCLUSIONS

Current smokers demonstrated cue reactivity to the use of an HTP as they reported increases in both cigarette and e-cigarette craving after exposure. All smoking groups reported e-cigarette reactivity to the HTP cue. As HTPs gain traction globally, it is crucial to consider how their use may influence active users and passive viewers to inform future health policies.

IMPLICATIONS

Noncombustible nicotine delivery systems are known cues for cigarette smoking and e-cigarette vaping, and this study examined whether relatively novel heated tobacco products (HTPs) may also act as a smoking or vaping cue in adults across varied smoking backgrounds. Results showed that passive exposure to HTP use increased desire for both a cigarette and an e-cigarette in current smokers and also increased desire for an e-cigarette in former and nonsmokers. Thus given its similarity to smoking and vaping, HTP use may affect passive observers and could play a role in perpetuating the dual use of cigarettes and vape products.

Chemosensory Contributions of E-Cigarette Additives on Nicotine Use

While rates of smoking combustible cigarettes in the United States have trended down in recent years, use of electronic cigarettes (e-cigarettes) has dramatically increased, especially among adolescents. The vast majority of e-cigarette users consume "flavored" products that contain a variety of chemosensory-rich additives, and recent literature suggests that these additives have led to the current "teen vaping epidemic." This review, covering research from both human and rodent models, provides a comprehensive overview of the sensory implications of e-cigarette additives and what is currently known about their impact on nicotine use. In doing so, we specifically address the oronasal sensory contributions of e-cigarette additives. Finally, we summarize the existing gaps in the field and highlight future directions needed to better understand the powerful influence of these additives on nicotine use.

The development and validation of an electronic nicotine delivery system (ENDS) image cue stimulus set

RATIONALE

Responsiveness to drug-related cues assesses drug reward in research studies. There are currently no validated visual image cues related to electronic nicotine delivery systems (ENDS), thus, this study aimed to develop and validate affective ENDS image cues.

METHODS

ENDS users and non-vaping individuals in the United States and Canada were recruited via Amazon MTurk. A total of 120 ENDS-related images and 56 neutral images, matched for visual similarity, were assessed. These images were either selected from public databases or were photographed by study staff. Closely adhering to the International Affective Picture System procedure, each participant rated 66 images one-by-one on dimensions of valence, arousal, dominance, and desire-to-vape where higher scores indicated greater feelings of happiness, excitement, loss of control, and desire to vape.

RESULTS

After excluding patterned responses, the data from 926 participants (610 ENDS users, and 316 non-vaping controls) were analyzed. When viewing ENDS-related images, desire-to-vape scores were correlated with valence (r = 0.55, p < 0.0005), arousal (r = 0.72, p < 0.0005), and dominance (r = 0.58, p < 0.0005) scores. Images that elicited greater desires to vape also elicited greater feelings of happiness and excitement, but less perceived control. Correlations between arousal and valence (r = 0.42, p < 0.0005) and dominance (r = 0.71, p < 0.0005) suggest that images that increased feelings of excitement also increased happiness and decreased perceived control.

CONCLUSIONS

Correlational findings of the affective ENDS-related images were similar to those of previous studies validating collections of tobacco and alcohol picture cues, supporting the future use of these stimuli in ENDS research.

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.

The rise and fall of e-cigarette cloud chasing appealing to youth

Electronic cigarette (e-cigarette) use continues to rise among youth with new devices and technology outpacing regulation. The "cloud chasing" phenomenon, whereby vapers compete or otherwise showcase the production of large or artistic exhaled aerosols from e-cigarettes, played a role in the early appeal of e-cigarette use in youth. This paper describes the sudden rise in the phenomenon of cloud chasing on social media and at vaping conventions due to the proliferation of second and third-generation powerful e-cigarette devices in their peak in 2015 and then their subsequent decline in the past few years. We describe four distinct factors that affected both the rise and fall in cloud chasing, including: 1) the rapid evolution of powerful e-cigarette devices, 2) the increase in social media promotions, 3) an inability of regulatory bodies to keep up with evolving ENDS technology, and 4) two recent widespread health concerns and conditions. Conclusions highlight the importance of swift regulation and effective health communication to mitigate unintended consequences of product evolution. It remains unknown whether such vape tricks and related competitions will reemerge and appeal to youth as store fronts reopen and devices continue to evolve.

Distinct influences of nicotine and sensorimotor stimuli on reducing cravings to smoke and vape among dual users

INTRODUCTION

When considering the clinical efficacy of e-cigarettes for smoking cessation, non-pharmacologic influences, such as conditioned reinforcers (e.g. sensorimotor stimuli), must be considered in addition to nicotine. The present study parsed the influences of nicotine delivery and sensorimotor stimuli (i.e, similarity to smoking) on cravings and other immediate outcomes of e-cigarette use.

METHOD

Participants (N = 127 dual users) completed an experimental ad-lib vaping session in one of 4 conditions: Drug (open label nicotine vs non-nicotine e-cigarettes) crossed with delivery apparatus (normal e-cigarette vs altered sensorimotor apparatus). It was hypothesized that participants who were deprived of the usual vaping stimuli would report less craving reduction via vaping. Nicotine was hypothesized to enhance physiological outcomes.

RESULTS

Moderate effects emerged for nicotine, whereas smaller effects were observed for the sensorimotor manipulation upon both cravings to smoke and cravings to vape. Contrary to the hypothesis, participants who vaped using the altered sensorimotor apparatus reported greater craving reduction compared to those who used normal e-cigarettes. Nicotine delivery also had moderate effects on psychological reward. Main effects were not moderated by gender, withdrawal, or dependence.

CONCLUSIONS

Findings support the role of nicotine in reducing cravings via vaping. They also suggest that sensorimotor similarities to smoking may be less important among experienced vapers or dual users. Indeed, in this sample, the altered sensorimotor apparatus may have reduced craving via distraction or other mechanisms.

Electronic nicotine delivery systems (ENDS) cue reactivity in dual users: A combined analysis

BACKGROUND

Cigarette smokers report increases in smoking urge in response to exposure to electronic nicotine delivery systems (ENDS) and dual users, i.e. smokers who also vape ENDS, may exhibit greater cue reactivity than exclusive smokers. The current investigation examined reactivity to a variety of ENDS cues across a large sample of cigarette smokers and dual ENDS users.

METHODS

Young adult smokers (N = 345; >5 cigarettes per day) were recruited between 2013-2019 for participation in a series of within-subjects laboratory-based studies. Participants completed surveys before and after exposure to a confederate-delivered control cue (water) and an active cue, including cigarette or ENDS cues ranging from first generation "cigalikes" to a fourth generation "pod-mod". Main outcomes were post-cue changes in desire for combustible cigarettes and e-cigarettes, and smoking behavior as determined by the smoking latency portion of the Smoking Lapse Paradigm after cue exposure.

RESULTS

Relative to smokers who do not use ENDS, dual users demonstrated higher baseline desire for ENDS and greater ENDS cue reactivity (across product types) in terms of post-cue increases in smoking urge and shorter latency to smoking choice. In contrast, reactivity to the cigarette cue was similar across groups.

CONCLUSIONS

Dual users show heightened ENDS cue reactivity on smoking urge and behavior relative to never users of ENDS, regardless of the type of ENDS cue. Given their reactivity to both cigarette and ENDS cues, it may be difficult for dual users to transition to exclusive vaping or quit tobacco product use altogether.

Effects of Visual Exposure to IQOS Use on Smoking Urge and Behavior

Objectives

In this study, we examined whether visual exposure to the heated tobacco product (HTP) IQOS, which was authorized for sale by the US Food and Drug Administration in 2019, acts as a cue to increase cigarette craving and smoking behavior among smokers.

Methods

Young adult smokers (N = 105) were randomly assigned to view a video depicting use of either IQOS or bottled water. Main outcomes were changes in cigarette and e-cigarette desire and latency to smoke between the groups. We also examined participants' attitudes about the actors using IQOS and drinking water in the videos.

Results

Exposure to the use of IQOS acutely increased observers' ratings of smoking urge and desire for a cigarette and an e-cigarette. The IQOS cue, compared with the water cue, also produced a marginally significant shorter latency to smoke. Participants perceived actors as less likeable and friendly when using IQOS than when drinking water.

Conclusions

Results showed that exposure to IQOS produced smoking urge and behavior in young adult smokers, implicating IQOS use as a smoking and vaping cue. As HTPs gain popularity, product impact on passive observers should be included in their risk-benefit profile.

E-cigarettes: How can they help smokers quit without addicting a new generation?

The dramatic increase in youth use of electronic nicotine delivery systems (ENDS; e.g., e-cigarettes) in the United States has focused regulatory efforts to address this concern while still encouraging smokers to switch completely to lower risk products or quit all tobacco product use. Increases in the minimum age for purchase of all tobacco products and changes in enforcement policy for ENDS have been recently enacted in an effort to address the youth vaping epidemic. Since all ENDS marketed after February 15, 2007 will be required to meet the "appropriate for the protection of public health" standard for marketing authorization of new products, ENDS manufacturers will have to demonstrate, in part, that their products help lessen the adverse impact on youth use. Some, such as disallowing flavors other than tobacco or menthol or limiting nicotine delivery, may help reduce youth use but could also inhibit smokers from quitting smoking. Other approaches, including reducing the high-tech appearance and discreteness of ENDS, discontinuing use of coupons and two-for-one type price incentives for ENDS, limiting retail sales of these products to adult-only facilities, and incorporating technological innovations such as biometrics or geofencing into ENDS, may help manufacturers demonstrate that marketing of their products would help reduce youth use of ENDS and lessen the epidemic, while still assuring adult smokers have access to products that encourage discontinuing combusted product use.

Exposure to JUUL use: cue reactivity effects in young adult current and former smokers

BACKGROUND

Exposure to the use of first, second and third generations of electronic cigarettes (e-cigarettes) elicits the desire to vape and smoke among observers, as well as facilitates smoking behaviour. Given the rapid rise in the popularity of the pod mod JUUL, we examined whether observing the use of this device would elicit similar responses in smokers. Exploratory analyses were also conducted to determine whether JUUL can act as a smoking cue for former smokers.

METHODS

The sample consisted of 82 young adult participants (62 current smokers and 20 former smokers approximately 1 year smoke free). The study examined their response to observing use of bottled water (control cue) and JUUL (active cue) in a controlled laboratory paradigm. Both cues were delivered by a trained study confederate under the guise of a social interaction task, and participants completed mood and desire and urge surveys precue and postcue exposures.

RESULTS

In current smokers, exposure to the JUUL cue increased smoking urge and desire for a cigarette, mod/vape pen and JUUL, and two-thirds chose to smoke in the behavioural analogue task. In former smokers, the JUUL cue evoked modest and transient increases in desire for a cigarette and JUUL.

CONCLUSIONS

The use of JUUL affects the user and elicits responses in observers; this study is the first to demonstrate that exposure to JUUL use may act as a smoking cue and exposure to JUUL use may affect tobacco control efforts.

[E-cigarette use among cannabis users and multi-users of psychoactive products: A cohort study]

INTRODUCTION

There is no evidence in the literature relating to the evolution of e-cigarette use among cannabis users and multi-users (of alcohol, tobacco or cannabis).

OBJECTIVE

To describe the evolution over 12 months of e-cigarette use in cannabis users and multi-users.

METHODS

A prospective observational cohort study in general practice, between 2015 and 2016.

RESULTS

A total of 4.8% of monitored cannabis users remained or became current users of e-cigarettes by the end of the monitoring period versus 4.5% among non-users of cannabis, with no statistically significant difference. A total of 5.1% of monitored multi-users remained or became current users of e-cigarettes by the end of the monitoring period versus 2.4% among the non-multi-users, with no statistically significant difference. Cannabis users and multi-users reported more e-cigarette experimentation through curiosity and following someone's suggestion, compared to non-cannabis users or non multi-users. No statistically significant association was found between cannabis or multi-drug use and staying or becoming a current e-cigarette user over 12 months.

CONCLUSION

Cannabis users and multi-users would tend to experiment with e-cigarettes more than other patients but this use would not be sustained.

Cue salience of the use of an electronic nicotine delivery system (ENDS) device marketed to women

INTRODUCTION

Passive exposure to the use of electronic nicotine delivery systems (ENDS or e-cigarettes) has been shown to generalize as a smoking cue. As young adult women in particular are increasingly targeted by ENDS distributors, the present study examined whether passive exposure to the use of a female-marketed ENDS product selectively enhanced smoking urge, cigarette and e-cigarette desire, and smoking behavior among women (vs men) smokers.

METHODS

Using a mixed design, young adult smokers (n = 64; mean age 28.2 yrs.; ≥5 cigarettes/day) observed a study confederate drink bottled water (control cue) and then vape a female-marketed tank-based ENDS (active cue). Main measures were the Brief Questionnaire of Smoking Urges (BQSU) and visual analog scales (VAS) for cigarette and e-cigarette desire pre- and post-cue exposure, followed by a smoking latency task.

RESULTS

Compared to the control cue, the female-marketed ENDS cue increased smoking urge and desire for cigarettes and e-cigarettes to a similar extent in women and men. It also affected subsequent smoking behavior similarly between the sexes, with 68% of men and 58% of women opting to smoke (vs. obtaining monetary reinforcers).

CONCLUSIONS

Both women and men were sensitive to the use of the female-marketed ENDS as a smoking cue. Consistent with prior work by our group, findings demonstrate the cue salience of ENDS, which may be attributable to the aspects of vaping that resemble traditional smoking (e.g. hand-to-mouth and inhalation and exhalation behaviors).