The need for a comprehensive framework

Conditioned enhancement of the nicotine reinforcer

This study was designed to assess whether nicotine can acquire additional reinforcing properties through associations with other rewards. To this end, rats self-administered nicotine-alone (0.01 mg/kg) or nicotine paired with access to sucrose during the conditioning phase. In the subsequent challenge phase, we tested the effect of nicotine-sucrose pairings on the reinforcing effects of nicotine using a progressive ratio schedule of reinforcement. Using this approach, we show that (a) rats in both paired and nicotine-alone conditions self-administered similar amounts of nicotine in the initial conditioning phase of the study when intake was limited to 10 infusions per session, (b) nicotine rapidly acquired control over goal-tracking behavior in the paired condition, (c) rats that had a history of nicotine and sucrose pairings worked harder and took more nicotine as measured on a progressive ratio using a distinct response form, and (d) conditioned goal-tracking evoked by nicotine did not show extinction when sucrose was no longer paired with nicotine over the 11 days of nicotine self-administration on a progressive ratio schedule of reinforcement. Overall, our results demonstrate that in addition to the multifaceted nature of nicotine stimulus that includes primary reinforcing effects, conditioned reinforcing effects, and reward enhancing effects, nicotine can also acquire additional reinforcing properties through associations with other rewards. This ability to acquire additional reinforcing properties through associative learning may contribute to the development and perpetuation of tobacco use disorder. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Trends in Tobacco Use Among Adolescents by Grade, Sex, and Race, 1991-2019

IMPORTANCE

Use of e-cigarettes increased among adolescents between 2011 and 2019. However, whether these changes are affecting patterns of use of other tobacco products, especially cigarettes, remains unclear.

OBJECTIVE

To examine the long-term and recent trends in cigarette smoking and smokeless tobacco product use among US adolescents by grade (8th, 10th, and 12th), sex (male and female), and race (White and Black).

DESIGN, SETTING, AND PARTICIPANTS

In this cross-sectional study, joinpoint regression analyses were performed to characterize trends in tobacco product use for key sociodemographic groups, identifying change of trend years (joinpoints). Students in the 8th, 10th, and 12th grades at US secondary schools and high schools who participated in the nationally representative Monitoring the Future survey from January 7, 1991, to June 3, 2019, were evaluated.

EXPOSURES

Cigarette smoking and smokeless tobacco product use during the past 30 days.

MAIN OUTCOMES AND MEASURES

Past 30-day and daily prevalence of cigarette smoking and smokeless tobacco product use by year, grade, sex, and race. The prevalence trend segments, change of trend years (joinpoints), and annual percentage change (APC) in prevalence within each trend segment were estimated using joinpoint regression.

RESULTS

Since 1991, 487 335 8th-grade, 447 310 10th-grade, and 424 236 12th-grade students have completed the Monitoring the Future survey (including 663 663 girls and 632 698 boys [those who did not respond to the sex question in the survey were excluded from the sex analyses]). Past 30-day and daily smoking prevalence increased in all groups analyzed from 1991 until 1996 and 1997 and has been decreasing ever since, with more rapid reductions in recent years. For example, daily smoking among 12th-grade boys increased at an APC of 4.9% (95% CI, 3.5%-6.3%) from 1991 to 1998, decreased at an APC of -8.0% (95% CI, -9.3% to -6.7%) from 1998 to 2006, decreased at an APC of -1.6% (95% CI, -4.6% to 1.5%) from 2006 to 2012, and decreased at an APC of -17.4% (95% CI, -19.4% to -15.4%) from 2012 to 2019. Similar results were observed for boys in the 8th grade (5.0% [95% CI, 0.1%-10.2%] for 1991-1996, -8.8% [95% CI, -10.0% to -7.6%] for 1996-2011, and -17.3% [95% CI, -22.2% to -12.0%] for 2011-2019) and 10th grade (7.1% [95% CI, 3.7%-10.7%] for 1991-1997, -11.1% [95% CI, -13.9% to -8.2%] for 1997-2005,-0.7% [95% CI, -5.9% to 4.9%] for 2005-2011, and -17.9 [95%, -21.7% to -13.9%] for 2011-2019), for girls in 8th grade (10.9% [95% CI, 5.0%-17.2%] for 1991-1996 and -10.8% [95% CI, -11.7% to -10.0% for 1996-2019), 10th grade (7.2% [95% CI, 3.9%-10.7%] for 1991-1997, -9.5% [95% CI, -10.5% to -8.6%] for 1997-2012, and -16.3% [95% CI, -21.8% to -10.4%] for 2012-2019), and 12th grade (6.5% [95% CI, 3.6%-9.5%] for 1991-1997, -7.2% [95% CI, -8.1% to -6.3%] for 1997-2012, and -17.5% [95% CI, -21.2% to -13.6%] for 2012-2019). Results were similar, too, for Black adolescents (2015-2019 average annual percentage change: -8.6% [95% CI, -10.3% to -6.8%] for 8th graders; -17.7% [95% CI, -26.3% to -8.2%] for 10th graders; and -18.3% [95% CI, -23.9% to -12.2%] for 12th graders) and White adolescents (2015-2019 average annual percentage change: -17.3% [95% CI, -20.6% to -13.7%] for 8th graders; -16.9% [95% CI, -20.5% to -13.2%] for 10th graders; and -17.0% [95% CI, -20.5% to -13.2%] for 12th graders). Smokeless tobacco was used more variably through 2012, followed by consistent decreases in the past 5 years. For instance, smokeless tobacco use in the past 30 days in 10th-grade boys decreased at an APC of -6.5% (95% CI, -7.5% to -5.4%) from 1991 to 2004, increased at an APC of 3.1% (95% CI, -0.8% to 7.1%) from 2004 to 2012, and decreased at an APC of -11.6% (95% CI, -15.7% to -7.4%) from 2012 to 2019. Similarly, daily smokeless tobacco use in 12th-grade boys decreased at an APC of -3.8% (95% CI, -5.4% to -2.1%) from 1992 to 2005, increased at an APC of 3.1% (95% CI, -0.2% to 6.5%) from 2005 to 2015, and decreased at an APC of -23.0% (95% CI, -33.3% to -11.0%) from 2015 to 2019.

CONCLUSIONS AND RELEVANCE

This cross-sectional study suggests that, despite the increase in the prevalence of e-cigarette use among adolescents between 2011 and 2019, the prevalence of cigarette and smokeless tobacco use has decreased more rapidly during the same period compared with earlier years.

Transitions between cigarette, ENDS and dual use in adults in the PATH study (waves 1-4): multistate transition modelling accounting for complex survey design

INTRODUCTION

Even prior to 2018, electronic nicotine delivery systems (ENDS) began to dramatically change the landscape of tobacco products and product use patterns in the USA.

METHODS

Using a Markov multistate transition model accounting for complex survey design, transition rates between never, non-current, cigarette, ENDS and dual use states were estimated for 23 253 adult participants in waves 1-4 (approximately 2013-2017) of the Population Assessment of Tobacco and Health study. We made short-term transition projections and estimated HRs for age, sex, race/ethnicity, education and income.

RESULTS

Cigarette use was persistent among adults, with 89.7% (95% CI 89.1% to 90.3%) of exclusive cigarette users and 86.1% (95% CI 84.4% to 87.9%) of dual users remaining cigarette users (either exclusive or dual) after one wave. In contrast, ENDS use was less persistent, with 72.1% (95% CI 69.6% to 74.6%) of exclusive ENDS users and 50.5% (95% CI 47.8% to 53.3%) of dual users remaining ENDS users (with or without cigarettes) after one wave. Exclusive ENDS users were more likely to start cigarette use after one wave than either never users (HR 25.2; 95% CI 20.9 to 30.5) or non-current users (HR 5.0; 95% CI 4.3 to 5.8). Dual users of ENDS and cigarettes were more likely to stop using cigarettes than exclusive cigarette users (HR 1.9; 95% CI 1.6 to 2.3). Transition rates varied among sociodemographic groups.

CONCLUSIONS

Multistate transition models are an effective tool for uncovering and characterising longitudinal patterns and determinants of tobacco use from complex survey data. ENDS use among US adults was less persistent than cigarette use prior to 2018.

Are e-cigarettes reviving the popularity of conventional smoking among Taiwanese male adolescents? A time-trend population-based analysis for 2004-2017

INTRODUCTION

In Taiwan, national tobacco use surveys show that e-cigarette use has increased since 2014 among youth, while, at the same time, conventional cigarette smoking has continuously decreased. The purpose of this study is to examine whether the increased popularity of e-cigarettes has undermined this favourable declining trend for cigarette smoking.

METHODS

We examined conventional cigarette and e-cigarette prevalence among male high school students (aged 16-18 years) and adults from 2004 to 2017, using data from cross-sectional nationally representative surveys. Applying interrupted time series analysis, we assessed whether there was a change in trend in 2014, when e-cigarette use started to gain popularity from long-term trends in prior years (2004-2013).

RESULTS

E-cigarette use prevalence increased from 2.5% in 2014 to 6.4% in 2017 among male high school students but was negligible among male adults, declining from 1.4% in 2015 to 0.8% in 2017. The annual relative decline in the cigarette smoking rate after e-cigarettes started to gain popularity was greater (-10%) than the long-term trend (-2%) among high school students. Among adults, the change in trend over time after e-cigarettes started to gain popularity was not significant (ie, not significantly different from 0).

CONCLUSIONS

The increased popularity of e-cigarettes since 2014 is associated with a greater decline in youth smoking, compared with previous years. On the contrary, e-cigarette use has remained very low among Taiwanese male adults and no additional impact on the conventional smoking trend is found.