Introduction: Electronic cigarettes (e-cigs) are becoming increasingly popular, but little is known about their dependence potential. This study aimed to assess ratings of dependence on electronic cigarettes and retrospectively compare them with rated dependence on tobacco cigarettes among a large sample of ex-smokers who switched to e-cigs. Methods: A total of 3,609 current users of e-cigs who were ex-cigarette smokers completed a 158-item online survey about their e-cig use, including 10 items designed to assess their previous dependence on cigarettes and 10 almost identical items, worded to assess their current dependence on e-cigs (range 0-20). Results: Scores on the 10-item Penn State (PS) Cigarette Dependence Index were significantly higher than on the comparable PS Electronic Cigarette Dependence Index (14.5 vs. 8.1, p < .0001). In multivariate analysis, those who had used e-cigs longer had higher e-cig dependence scores, as did those using more advanced e-cigs that were larger than a cigarette and had a manual button. Those using zero nicotine liquid had significantly lower e-cig dependence scores than those using 1-12 mg/ml, who scored significantly lower than those using 13 or greater mg/ml nicotine liquid (p < .003). Conclusions: Current e-cigarette users reported being less dependent on e-cigarettes than they retrospectively reported having been dependent on cigarettes prior to switching. E-cig dependence appears to vary by product characteristics and liquid nicotine concentration, and it may increase over time.

Introduction: Electronic cigarettes (e-cigs) are becoming increasingly popular but little is known about how e-cig users' transition between the different device types and what device characteristics and preferences may influence the transition. Methods: Four thousand four hundred twenty-one experienced e-cig users completed an online survey about their e-cig use, devices, and preferences. Participants included in analysis were ever cigarette smokers who used an e-cig at least 30 days in their lifetime and who reported the type of their first and current e-cig device and the nicotine concentration of their liquid. Analyses focused on transitions between "first generation" devices (same size as a cigarette with no button) and "advanced generation" devices (larger than a cigarette with a manual button) and differences between current users of each device type. Results: Most e-cig users (n = 2603, 58.9%) began use with a first generation device, and of these users, 63.7% subsequently transitioned to current use of an advanced generation device. Among users who began use with an advanced generation device (n = 1818, 41.1%), only 5.7% transitioned to a first generation device. Seventy-seven percent of current advanced generation e-cig users switched to their current device in order to obtain a "more satisfying hit. " Battery capabilities and liquid flavor choices also influenced device choice. Conclusion: E-cig users commonly begin use with a device shaped like a cigarette and transition to a larger device with a more powerful battery, a button for manual activation and a wider choice of liquid flavors.

Background Awareness and use of electronic cigarettes (e-cigs) has increased significantly in the last five years, but little is known about the experiences, satisfaction, opinions and preferences of e-cigs users. Method 1177 participants completed an online survey about their electronic cigarette preferences, of which 200 were randomly selected for analysis. The data was analyzed using both qualitative and quantitative methods. Results Participants found the design, the ability to customize, and the quality of vapor to be the most important characteristics of the device. Participants thought the most positive aspects of e-cig use were help to quit smoking, improved overall health, and reduced cost. The negative aspects associated with use were mainly related to side effects, such as dry mouth. When asked to explain how e-cigs were used differently than cigarettes, participants reported puffing more regularly, but taking fewer puffs per session. Conclusions Experienced e-cig users stated that initiating e-cig use helped them to quit or reduce their conventional smoking, which they believe reduced their health risks. In comparison to cigarette smoking, e-cig users reported using their e-cig more times per day, but with fewer puffs at each use time. Users acknowledged that more research is needed to understand the safety and long-term effects of use. They mentioned dry mouth as a common side effect and common problems with reliability of e-cigs. Understanding these views may help health professionals to assess and assist e-cig users, and in the future, may help regulators to improve quality and reduce risks.

Background The capability of electronic cigarette devices (e-cigs) to deliver nicotine is key to their potential to replace combustible cigarettes. We compared nicotine delivery and subjective effects associated with the use of two classes of e-cigarettes and cigarettes. Methods 14 e-cigarette users were instructed to vape their own e-cigarette device every 20 seconds for 10 minutes while blood was drawn at 1, 2, 4, 6, 8, 10,12, and 15 minutes after initiating vaping. Users rated withdrawal symptoms and side effects before and after vaping. E-cigarette devices were classified as first-generation (same size as cigarette, no activation button) or advanced (larger than cigarette with an activation button). Separately, 10 cigarette smokers completed a similar protocol. Fisher’s Exact Test and two-sided t-tests were used as appropriate to determine differences in outcomes between first-generation e-cigarette users, advanced e-cigarette users, and smokers. Results Compared to first-generation devices, advanced devices were associated with greater serum nicotine C max (ng/ml) (11.5 v. 2.8, p = 0.0231) and greater nicotine boost (ng/ml) (10.8 v. 1.8, p = 0.0177). Overall, e-cigarettes users experienced a significant reduction in withdrawal and craving, although there were no significant differences between users of first-generation and advanced devices. Comparing e-cigarettes overall to cigarettes, cigarettes were associated with greater C max (25.9 v. 9.0, p = 0.0043) and greater nicotine boost (21.0 v. 8.2, p = 0.0128). Conclusions Advanced e-cigarettes delivered significantly more nicotine than first-generation devices but less than combustible cigarettes. Overall, e-cigarette use was associated with a reduction in withdrawal and craving with no reported side effects. The wide variation in nicotine absorption from different e-cigarette devices should be considered in studies of e-cigarettes for smoking cessation.

As a group, cigarette smokers exhibit blunted subjective, behavioral, and neurobiological responses to nondrug incentives and rewards relative to nonsmokers. Findings from recent studies suggest, however, that there are large individual differences in the devaluation of nondrug rewards among smokers. Moreover, this variability appears to have significant clinical implications, as reduced sensitivity to nondrug rewards is associated with poorer smoking cessation outcomes. Currently, little is known about the neurobiological mechanisms that underlie these individual differences in the responsiveness to nondrug rewards. Here, we tested the hypothesis that individual variability in reward devaluation among smokers is linked to the functioning of the striatum. Specifically, functional magnetic resonance imaging was used to examine variability in the neural response to monetary outcomes in nicotine-deprived smokers anticipating an opportunity to smoke – circumstances found to heighten the devaluation of nondrug rewards by smokers in prior work. We also investigated whether individual differences in reward-related brain activity in those expecting to have access to cigarettes were associated with the degree to which the same individuals subsequently were willing to resist smoking in order to earn additional money. Our key finding was that deprived smokers who exhibited the weakest response to rewards (i.e., monetary gains) in the ventral striatum were least willing to refrain from smoking for monetary reinforcement. These results provide evidence that outcome-related signals in the ventral striatum serve as a marker for clinically meaningful individual differences in reward-motivated behavior among nicotine-deprived smokers.