Effects of Social Media on Adolescents' Willingness and Intention to Use E-Cigarettes: An Experimental Investigation.

INTRODUCTION: This study examined the effects of experimentally manipulated social media exposure on adolescents' willingness and intention to use e-cigarettes. AIMS AND METHODS: Participants were 135 adolescents of age 13-18 (52.6% female, mean age = 15.3) in California. Participants viewed six social media posts online in a 2 (post source: peer or advertisement) × 2 (e-cigarette content exposure: heavy or light) between-subjects design. Analyses were weighted to population benchmarks. We examined adolescents' beliefs, willingness, and intention to use e-cigarettes in association with social media use intensity in daily life and with experimentally manipulated exposure to social media posts that varied by source (peer or advertisement) and content (e-cigarette heavy or light). RESULTS: Greater social media use in daily life was associated with greater willingness and intention to use e-cigarettes and more positive attitudes, greater perceived norms, and lower perceived danger of e-cigarette use (all p-values <.01). In tests of the experimental exposures, heavy (vs. light) e-cigarette content resulted in greater intention (p = .049) to use e-cigarettes and more positive attitudes (p = .019). Viewing advertisements (vs. peer-generated posts) resulted in greater willingness and intention (p-values <.01) to use e-cigarettes, more positive attitudes (p = .003), and greater norm perceptions (p = .009). The interaction effect of post source by post content was not significant for any of the outcomes (all p-values >.529). CONCLUSIONS: Greater social media use and heavier exposure to advertisements and e-cigarette content in social media posts are associated with a greater risk for e-cigarette use among adolescents. Regulatory action is needed to prohibit sponsored e-cigarette content on social media platforms used by youth. IMPLICATIONS: Adolescents who use social media intensely may be at higher risk for e-cigarette use. Even brief exposure to e-cigarette content on social media was associated with greater intention to use and more positive attitudes toward e-cigarettes. Regulatory action should be taken to prohibit sponsored e-cigarette content on social media used by young people, including posts by influencers who appeal to young people.

Neural Correlates of Smartphone Dependence in Adolescents.

Increases in depressive and suicide-related symptoms among United States adolescents have been recently linked to increased use of smartphones. Understanding of the brain mechanisms that underlie the potential smartphone dependence may help develop interventions to address this important problem. In this exploratory study, we investigated the neural mechanisms underlying potential smartphone dependence in a sample of 19 adolescent volunteers who completed self-assessments of their smartphone dependence, depressive symptoms, and sleep problems. All 19 adolescents underwent diffusion MRI that allowed for assessment of white matter structural connectivity within the framework of connectomics. Based on previous literature on the neurobiology of addiction, we hypothesized a disruption of network centrality of three nodes in the mesolimbic network: Nucleus Accumbens, anterior cingulate cortex, and amygdala. Our results showed positive correlations between the node centrality of the right amygdala and self-reported smartphone dependence, between smartphone dependence and sleep problems, and between sleep problems and depressive symptoms. A higher phone dependence was observed in females compared to males. Supported by these results, we propose a model of how smartphone dependence can be linked to aberrations in brain networks, sex, sleep disturbances, and depression in adolescents.

Abuse liability assessment of the JUUL system in four flavors relative to combustible cigarette, nicotine gum and a comparator electronic nicotine delivery system among adult smokers.

BACKGROUND: The abuse liability of the JUUL System (JS) in four flavors were evaluated compared to combustible cigarettes, nicotine gum, and a comparator electronic nicotine delivery system (ENDS) with pharmacokinetics (PK) and subjective effects. METHODS: Adult smokers (N = 66; 50.0 % female; mean age = 41.1; 63.6 % white) completed a 7-arm within-subjects cross-over product-use study while confined to a clinical laboratory. Participants used JS in four flavors (Virginia Tobacco, Mango, Mint, Creme, [5.0 % nicotine; 59 mg/mL]), their usual brand (UB) cigarette, a comparator ENDS (VUSE Solo; 4.8 % nicotine, tobacco-flavor), and mint nicotine gum (4 mg) under controlled use conditions. After each product use, nicotine PK and subjective effects were assessed. RESULTS: Maximum plasma nicotine levels (Cmax-BL), rate of plasma nicotine rise, overall nicotine exposure (AUC0-60-BL), and subjective liking and satisfaction of JS were significantly lower than UB cigarettes. These parameters were generally greater for JS than nicotine gum; the comparator ENDS was somewhat lower but within the range of JS. Nicotine PK did not differ among the Mint, Mango, and Virginia Tobacco JS flavors. Mint and Mango were rated as more satisfying than Virginia Tobacco and Creme. CONCLUSIONS: Controlled use of JS among adult smokers resulted in nicotine delivery, product liking, and satisfaction that were less than that of combustible cigarettes but generally greater than nicotine gum. These results support the conclusion that JS has lower abuse liability than combustible cigarettes, higher abuse liability than nicotine gum, and may provide sufficient nicotine delivery and satisfying effects to support substitution for combustible cigarettes among adult smokers.

Abuse liability assessment of the JUUL system in two nicotine concentrations compared to combustible cigarette, nicotine gum and comparator electronic nicotine delivery system.

BACKGROUND: To assess the abuse liability of the JUUL System (JS) in 5.0 % (59 mg/mL) and 3.0 % (35 mg/mL) nicotine concentrations. METHODS: Adult smokers (N = 146; 45.9 % female; mean age = 41.29 years) were randomized to one of four study flavor arms and then to a within-subjects cross-over sequence for five test product categories: (1) JS 5.0 % nicotine concentration; (2) JS 3.0 % nicotine; (3) usual brand (UB) cigarette; (4) 4 mg mint nicotine gum; (5) comparator ENDS (VUSE Alto 5.0 % nicotine). Products were tested by ad libitum use (5 min for ENDS and cigarette; 30 min for gum); nicotine pharmacokinetic (PK) parameters and subjective effects were assessed following use. RESULTS: Maximum plasma nicotine concentration (Cmax-BL), rate of plasma nicotine rise and total nicotine exposure (AUC0-60-BL) of UB cigarette were significantly greater than all other test products. The comparator ENDS was significantly greater than 5.0 % and 3.0 % JS and nicotine gum on Cmax-BL, rate of plasma nicotine rise, and AUC0-60-BL; Cmax-BL of JS 5.0 % was significantly greater than JS 3.0 % and nicotine gum. Product liking and satisfying effects were significantly highest for the UB cigarette; JS products and comparator ENDS did not significantly differ and were rated higher than nicotine gum on most subjective measures. CONCLUSIONS: These results suggest that the abuse liability of both 5.0 % and 3.0 % JS is: (1) substantially lower than UB cigarette; (2) somewhat lower than comparator ENDS; and (3) higher than nicotine gum. Additionally, the abuse liability of JS 5.0 % is somewhat higher than JS 3.0 %.

High-dose and low-dose varenicline for smoking cessation in adolescents: a randomised, placebo-controlled trial.

BACKGROUND: Although cigarette smoking typically begins in adolescence, evidence for successful pharmacological smoking cessation interventions for this population is scarce. In adult smokers, varenicline is the most effective single pharmacotherapy. The aim of this study was to assess the efficacy and tolerability of varenicline for smoking cessation in adolescents. METHODS: We did a randomised, placebo-controlled trial with adolescent smokers aged 12-19 years who were seeking treatment to quit at 57 outpatient centres (in the USA, Russia, South Korea, Taiwan, Canada, and Georgia). Participants were randomly assigned (1:1:1) to receive 12 weeks of high-dose varenicline (1 mg twice daily; 0·5 mg twice daily if bodyweight ≤55 kg), low-dose varenicline (0·5 mg twice daily; 0·5 mg once daily if bodyweight ≤55 kg), or placebo, then followed up for 40 additional weeks. At all visits, participants received brief, developmentally tailored smoking cessation counselling (<10 min per session) delivered by a trained counsellor. The primary efficacy outcome was continuous abstinence from weeks 9 to 12, measured via a Nicotine Use Inventory and confirmed by urine cotinine testing. The primary tolerability outcome was frequency of treatment-emergent adverse events, including neuropsychiatric adverse events, occurring after the first dose and within 30 days of the last dose of study medication. This trial is registered with ClinicalTrials.gov, NCT01312909. FINDINGS: Between April 26, 2011, and Jan 18, 2018, 312 participants were enrolled and completed participation in the study: 109 in the high-dose varenicline group, 103 in the low-dose varenicline group, and 100 in the placebo group. The continuous abstinence rates from week 9 to 12 were 20% (22 of 109) in the high-dose varenicline group, 27% (28 of 103) in the low-dose varenicline group, and 18% (18 of 100) in the placebo group. Abstinence rates between high-dose varenicline and placebo groups (odds ratio [OR] 1·18 [95% CI 0·59-2·37]; p=0·63) and between low-dose varenicline and placebo groups (1·73 [0·88-3·39]; p=0·11) did not differ significantly. Treatment-emergent adverse events occurred in 65 (60%) of 108 participants in the high-dose group, 53 (53%) of 100 in the low-dose group, and 52 (53%) of 99 in the placebo group, and most were rated as mild. Neuropsychiatric treatment-emergent adverse events occurred in 18 (17%) of 108 participants in the high-dose group, 11 (11%) of 100 in the low-dose group, and 12 (12%) of 99 in the placebo group, and none was rated as severe. INTERPRETATION: This trial did not show an advantage in abstinence with varenicline compared with placebo among adolescent smokers. The rates of treatment-emergent adverse events were similar to those in previous trials of adult smokers, raising no new tolerability signals. These findings do not support the use of varenicline as a first-line pharmacotherapy for smoking cessation in adolescents. FUNDING: Pfizer.

Online patient-provider cannabis consultations.

Cannabis has been legalized, decriminalized, or medicalized in over half the U.S. states. With restrictions on cannabis research, accepted standards to guide clinical practice are lacking. Analyzing online communications through a digital health platform, we characterized patient questions about cannabis use and provider responses. Coded for content were 4579 questions posted anonymously online between March 2011 through January 2017, and the responses from 1439 U.S. licensed clinicians. Provider responses to medical cannabis use questions were coded for sentiment: "negative", "positive", and "mixed." Responses could be "thanked" by patients and receive "agrees" from providers. The most frequent themes were detection of cannabis use (25.3%), health harms (19.9%), co-use with other substances (9.1%), and medical use (8.2%). The 425 medical cannabis use questions most frequently related to treatment of mental illness (20.3%), pain (20.0%), and cancer care (6.7%). The 762 provider responses regarding medical cannabis use were coded for sentiment as 59.6% negative, 28.6% mixed, and 11.8% positive. Provider sentiment was most positive regarding cannabis use for palliative care and most negative for treating respiratory conditions, poor appetite, and mental illness. The proportion of positive sentiment responses increased from 17.6% to 32.4%. Provider responses coded as negative sentiment received more provider "Agrees" (mean rank = 280) than those coded as positive (mean rank = 215), beta coefficient = 0.33; 95% CI: 0.05, 0.62; p = .02. Cannabis use is a health topic of public interest. Variability in provider responses reflects the need for more research and consensus building to inform evidence-based clinical guidelines for cannabis use in medicine.

Measuring e-cigarette addiction among adolescents.

BACKGROUND AND OBJECTIVES: With high rates of use and uncertain consequences, valid electronic cigarette (e-cigarette) use frequency and addiction measures for adolescents are needed. This cross-sectional study examined correlations for multiple measures of adolescent e-cigarette use with nicotine exposure quantified with salivary cotinine levels. METHODS: Adolescents (N=173, age 13-18) who reported past-month e-cigarette use were recruited from the San Francisco Bay Area. Participants self-reported: (1) days of e-cigarette use in a typical month, (2) number of e-cigarette sessions in a typical day (sessions per day; SPD) and the (3) E-Cigarette Addiction Severity Index (EASI). Participants also completed the 10-item Penn State Electronic Cigarette Dependence Index (ECDI), which we examined in full and as a 2-item Heaviness of Vaping Index (HVI; the sum of the ECDI items on use frequency and time to first vaping on wakening). Sessions per month (SPM) were calculated using days per month and SPD. Cotinine levels, SPD and SPM were log-transformed. RESULTS: Among frequency measures, SPM correlated most strongly with cotinine (r=0.59), followed closely by days per month (r=0.58) and SPD (r=0.57), p<0.001. Among dependence measures, the EASI correlated most strongly with cotinine (r=0.51), closely followed by the ECDI and HVI (r's=0.50), all p's<0.001. CONCLUSIONS: Adolescents' reports of frequency of e-cigarette use and degree of addiction correlated significantly with cotinine as a biomarker of nicotine exposure. We recommend the EASI and days per month as brief general measures. SPM and the ECDI are more extensive measures that may yield a more nuanced understanding of use.

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.

Associations between marijuana use and tobacco cessation outcomes in young adults.

Marijuana and tobacco co-use is common among young adults, and findings are mixed regarding the association between marijuana use and smoking cessation outcomes. This study examined the longitudinal relationships between marijuana use and smoking cessation outcomes among young adults (aged 18-25 years; N = 500) enrolled in a 3-month smoking cessation intervention on Facebook. At baseline and 3, 6, and 12 months, participants reported their marijuana use and their smoking behaviors (seven-day point prevalence abstinence from smoking, cigarettes per day, quit attempts) and readiness to quit. Longitudinal analyses controlled for experimental condition and adjusted for baseline stage of change, baseline average cigarettes per day, sex, alcohol use, and age participants began smoking regularly. Use of marijuana by young adult smokers was associated with a lower likelihood of reduced smoking (OR = 0.71, 95% CI [0.51, 0.98], p = .036) and a lower likelihood of abstaining from smoking (OR = 0.56, 95% CI [0.35, 0.90], p = .017) in the past seven days, as assessed over 12 months of follow-up. Use of marijuana was not significantly associated with perceptions of or engagement in the smoking cessation intervention, stage of change for quitting smoking, or tobacco quit attempts (all p's > 0.08). Study findings indicate that while marijuana use is unrelated to motivation to quit tobacco and engage in cessation interventions, marijuana use is associated with less success in reducing and abstaining from tobacco. Additional support and targeted tobacco cessation strategies to address challenges associated with marijuana co-use may be needed.

Prevalence and correlates of adolescents' e-cigarette use frequency and dependence.

BACKGROUND: Understanding predictors of e-cigarette use among adolescents in the context of wide availability and extreme popularity of these products is important for prevention and treatment. This study identifies correlates of e-cigarette use frequency and dependence among adolescent users. METHODS: Adolescent e-cigarette users (N = 173) were recruited from the San Francisco Bay Area. Participants reported demographic and psychosocial characteristics, e-cigarette use behaviors, and cigarette use. Bivariate relationships between potential correlates were examined, and correlates significant at p < .10 were included in full models predicting frequency and dependence. RESULTS: In the full models, frequent use was associated with receiving one's first e-cigarette from a family member rather than a friend (r = -0.23, p < .001) or a store ( = -0.13, p = .037), using nicotine in all e-cigarettes versus some e-cigarettes (r = -0.17, p = .007) or unknown nicotine use (r = -0.15, p = .014), using a customizable device versus a Juul (r = -0.22, p < .001), vape pen (r = -0.20, p = .002), or other/unknown device (r = -0.16, p = .009), and friends' e-cigarette use (r = 0.20, p = .002). Dependence was associated with younger age of first use (r = -0.18, p = .012), friends' use (r = 0.18, p = .01), and recent cigarette use (r = 0.17, p = .019). CONCLUSIONS: When assessing problematic e-cigarette use among adolescents, it is important to consider social factors (e.g., friends' and family members' e-cigarette use), device type, and dual use with cigarettes.

Adolescent Exposure to Toxic Volatile Organic Chemicals From E-Cigarettes.

BACKGROUND: There is an urgent need to understand the safety of e-cigarettes with adolescents. We sought to identify the presence of chemical toxicants associated with e-cigarette use among adolescents. METHODS: Adolescent e-cigarette users (≥1 use within the past 30 days, ≥10 lifetime e-cigarette use episodes) were divided into e-cigarette-only users (no cigarettes in the past 30 days, urine 4-[methylnitrosamino]-1-[3-pyridyl]-1-butanol [NNAL] level <1 pg/mL of creatinine; n = 67), dual users (use of cigarettes in the past 30 days in addition to e-cigarettes, NNAL level >30 pg/mL; n = 16), and never-using controls (N = 20). Saliva was collected within 24 hours of the last e-cigarette use for analysis of cotinine and urine for analysis of NNAL and levels of 8 volatile organic chemical compounds. Bivariate analyses compared e-cigarette-only users with dual users, and regression analyses compared e-cigarette-only users with dual users and controls on levels of toxicants. RESULTS: The participants were 16.4 years old on average. Urine excretion of metabolites of benzene, ethylene oxide, acrylonitrile, acrolein, and acrylamide was significantly higher in dual users versus e-cigarette-only users (all P < .05). Excretion of metabolites of acrylonitrile, acrolein, propylene oxide, acrylamide, and crotonaldehyde were significantly higher in e-cigarette-only users compared with controls (all P < .05). CONCLUSIONS: Although e-cigarette vapor may be less hazardous than tobacco smoke, our findings can be used to challenge the idea that e-cigarette vapor is safe, because many of the volatile organic compounds we identified are carcinogenic. Messaging to teenagers should include warnings about the potential risk from toxic exposure to carcinogenic compounds generated by these products.

Polydrug use among urban adolescent cigarette smokers.

PURPOSE: Adolescent smokers are at increased risk for polydrug use, which is associated with more consequences than use of a single drug. Here we classified subgroups of polydrug use among urban adolescent cigarette-smokers; described the sociodemographic, smoking, and depression correlates; and identified three-year outcomes associated with subgroup membership. METHODS: Adolescent cigarette smokers (N=176; Mage=16.1; 35% male; 27% white) completed surveys assessing drug use, smoking characteristics, demographics, and depressive symptoms at baseline and 12, 24, and 36months follow-up. RESULTS: Almost all participants (96%) reported using, on average, two (SD=0.97) substances (including other tobacco products) in addition to cigarettes. Latent class analysis revealed two distinct classes of polydrug users. "Limited Range Use" (84%) class members reported current use of other tobacco, alcohol, and marijuana, as did "Extended Range Use" class members (16%) who also reported current use of "harder drugs" (i.e., cocaine/crack, hallucinogens, ecstasy, and misused prescriptions). The classes did not differ on demographics or baseline likelihood of marijuana (χ2=0.25; p<0.62) or alcohol use (χ2=3.3; p<0.07). At baseline, a larger proportion of Extended Range Use class members reported both smoking the entire cigarette and symptoms of clinical depression. Extended Range Use class membership at baseline predicted higher mean depression scores at 24 and 36months. CONCLUSION: Adolescent cigarette-smokers who reported extended range use (18%) also reported symptoms of clinical depression at baseline and follow-up. These findings indicate a need for early monitoring of depression symptoms and prevention and cessation interventions targeting this high-risk group.

Reporting of cigar use among adolescent tobacco smokers.

INTRODUCTION: With the changing landscape of tobacco products, the divide between cigarettes and cigars is obscured, so understanding adolescent reporting of cigar use is needed to improve best practices for surveillance, screening, and prevention/intervention. This study examined adolescents' reported cigar use and correlates of use. METHODS: Participants (N=186) were 13-17year old tobacco users participating in a prospective study of adolescent smoking behaviors. Measurement occurred at baseline and 24-months, and included demographics, nicotine dependence, tobacco use, and quit attempts. Cigar use was assessed as, "have you smoked a cigar in the last 30days" and by brand specific use in the past 30days. FINDINGS: Cigar use was reported by 51 adolescents (27%), and increased to 76 (41%) when identifying by brand name. African Americans (32%) were more likely to smoke cigars than whites (10%, p<.01), Asian/Pacific Islanders (3%, p=.04), and multiracial participants (24%, p=.05). Cigarette-only users smoked more per day (p=.04) and had higher cotinine levels (p=.05) than cigar users. Number of prior quit attempts (p=.84) did not differ by group. Group differences in addiction were found between cigar users and cigarette only users (p<.01). At 24months, more baseline cigar users were tobacco abstinent than cigarette only users (16% versus 7%, p<0.01, respectively). CONCLUSIONS: Assessment of brand-specific cigars nearly doubled the reporting among adolescent users. Cigar users differed from cigarette-only users in consumption and likelihood of abstinence at 24-months. For more accurate surveillance and to inform treatment considerations, surveys of adolescent tobacco use should include cigars, including brand names, in the assessment strategy.

Recruitment of adolescents for a smoking study: use of traditional strategies and social media.

Engaging and retaining adolescents in research studies is challenging. Social media offers utility for expanding the sphere of research recruitment. This study examined and compared traditional and Facebook-based recruitment strategies on reach, enrollment, cost, and retention. Substance users aged 13-17 years were recruited through several methods, including social media, a study website, fliers, talks in schools, bus ads, and referrals. Study involvement included a one-time visit and semiannual follow-up surveys. 1265 individuals contacted study personnel; 629 were ineligible; 129 declined; and 200 participants enrolled. Facebook drew the greatest volume but had a high rate of ineligibles. Referrals were the most successful and cost-effective ($7 per enrolled participant); school talks were the least. Recruitment source was unrelated to retention success. Facebook may expand recruitment reach, but had greater financial costs and more ineligible contacts, resulting in fewer enrollees relative to traditional interpersonal recruitment methods. Referrals, though useful for study engagement, did not provide a differential benefit in terms of long-term retention.

Exploration of the Effect of Tobacco Smoking on Metabolic Measures in Young People Living with HIV.

We conducted cross-sectional, multicenter studies in HIV-positive young women and men to assess metabolic and morphologic complications from tobacco smoking in 372 behaviorally infected HIV-positive youth, aged 14-25 years. Measurements included self-reported tobacco use, fasting lipids, glucose, fat distribution, and bone mineral density (BMD; dual-energy X-ray absorptiometry scans). Overall, 144 (38.7%) self-reported smoking tobacco and 69 (47.9%) of these reported smoking greater than five cigarettes per day. Smokers versus nonsmokers had lower mean total cholesterol (146.0 versus 156.1 mg/dL; P < 0.01) and lower mean total body fat percent (24.1% versus 27.2%, P = 0.03). There was no difference between smokers and nonsmokers in fasting glucose or BMD. There appear to be only minimal effects from tobacco smoking on markers of cardiac risk and bone health in this population of HIV-positive youth. While these smokers may not have had sufficient exposure to tobacco to detect changes in the outcome measures, given the long-term risks associated with smoking and HIV, it is critical that we encourage HIV-positive youth smokers to quit before the deleterious effects become apparent.

Frequent marijuana use is associated with greater nicotine addiction in adolescent smokers.

BACKGROUND: Marijuana and tobacco are the substances used most commonly by adolescents and co-occurring use is common. Use of one substance may potentiate the addictive properties of the other. The current study examined the severity of nicotine addiction among teen smokers as a function of co-occurring marijuana use. METHODS: Participants were 165 adolescents (13-17 years old) who reported smoking at least 1 cigarette per day (CPD) in the past 30 days. General linear models examined the association of marijuana use with multiple measures of nicotine addiction including the Modified Fagerström Tolerance Questionnaire (mFTQ), Hooked on Nicotine Checklist (HONC), ICD-10, and the Nicotine Dependence Syndrome Scale (NDSS). RESULTS: The adolescent sample (mean age=16.1 years, SD=0.95) averaged 3.0 CPD (SD=3.0) for 1.98 years (SD=1.5). Most (79.5%) also smoked marijuana in the past 30 days. In models controlling for age, daily smoking status, and years of tobacco smoking, frequency of marijuana use accounted for 25-44% of the variance for all four measures of adolescent nicotine dependence. CONCLUSIONS: Marijuana use was associated with greater reported nicotine addiction among adolescent smokers. The findings suggest a role of marijuana in potentiating nicotine addiction and underscore the need for treatments that address both smoked substances.

Characteristics of adolescent intermittent and daily smokers.

INTRODUCTION: Intermittent smoking is common among adolescent smokers, but little is known about adolescent intermittent smokers (ITS). This study describes a cohort of adolescent ITS and compares them to adolescent daily smokers (DS) for the purpose of providing a more detailed characterization of adolescent ITS, specifically patterns of smoking, level of self-reported addiction, and experience with cessation METHODS: Participants were 124 ITS and 55 DS. ITS were defined as smoking at least monthly but <30 days per month; and DS as smoking daily. Participants completed demographic, smoking and addiction surveys including the HONC and mFTQ. RESULTS: ITS started smoking at an older age, smoked fewer cigarettes per day and scored significantly lower on addiction scales, but had similar difficulty to DS in quitting smoking with similar numbers of reported quit attempts. These differences remained after adjusting for years of smoking. ITS were more likely to smoke in social situations, while DS were more likely to smoke when angry. Both groups were equally likely to report smoking when drinking alcohol. CONCLUSIONS: We documented significant differences in smoking related behaviors between adolescent ITS and DS. Importantly, we also found that, despite low level infrequent smoking, ITS reported difficulty in quitting smoking. Given the risks from light and intermittent smoking, it is essential that we develop a greater understanding of adolescent ITS, including their difficulty in quitting and the contextual factors influencing their smoking, so that we may develop new targeted interventions.