Nicotine metabolism variability and nicotine addiction

State-of-the-art methods and devices for the generation, exposure, and collection of aerosols from heat-not-burn tobacco products

Tobacco harm reduction is increasingly recognized as a promising approach to accelerate the decline in smoking prevalence and smoking-related population harm. Potential modified risk tobacco products (MRTPs) must undergo a rigorous premarket toxicological risk assessment. The ability to reproducibly generate, collect, and use aerosols is critical for the characterization, and preclinical assessment of aerosol-based candidate MRTPs (cMRTPs), such as noncombusted cigarettes, also referred to as heated tobacco products, tobacco heating products, or heat-not-burn (HNB) tobacco products. HNB tobacco products generate a nicotine-containing aerosol by heating tobacco instead of burning it. The aerosols generated by HNB products are qualitatively and quantitatively highly different from cigarette smoke (CS). This constitutes technical and experimental challenges comparing the toxicity of HNB aerosols with CS. The methods and experimental setups that have been developed for the study of CS cannot be directly transposed to the study of HNB aerosols. Significant research efforts are dedicated to the development, characterization, and validation of experimental setups and methods suitable for HNB aerosols. They are described in this review, with a particular focus on the Tobacco Heating System version 2.2. This is intended to support further studies, the objective evaluation and verification of existing evidence, and the development of scientifically substantiated HNB MRTPs.

Nicotinic modulation of salience network connectivity and centrality in schizophrenia

Although functional abnormalities of the salience network are associated with schizophrenia, the acute effects of nicotine on its function and network dynamics during the resting state in patients are poorly understood. In this study, the effects of a 7 mg nicotine patch (vs. placebo) on salience network connectivity were examined in 17 patients with schizophrenia and 19 healthy subjects. We hypothesized abnormal connectivity between the salience network and other major networks (e.g. executive network) in patients under placebo administration and amelioration of this difference after nicotine. We also examined effects of nicotine on betweenness centrality (a measure of the influence of a region on information transfer throughout the brain) and local efficiency (a measure of local information transfer) of the network. A hybrid independent component analysis (ICA)/seed-based connectivity approach was implemented in which the salience network was extracted by ICA and cortical network peaks (anterior cingulate cortex (ACC), left and right insula) were used as seeds for whole-brain seed-to-voxel connectivity analysis. Significant drug X diagnosis interactions were observed between the ACC seed and superior parietal lobule and ventrolateral prefrontal cortex. A significant interaction effect was also observed between the left insula seed and middle cingulate cortex. During placebo conditions, abnormal connectivity predicted negative symptom severity and lower global functioning in patients. A significant drug X diagnosis interaction was also observed for betweenness centrality of the ACC. These results suggest that nicotine may target abnormalities in functional connectivity between salience and executive network areas in schizophrenia as well as affect the ability of the salience network to act as an integrator of global signaling in the disorder.

Examining the Effects of Parental Influence on Adolescent Smoking Behaviors: A Multilevel Analysis of the Global School-Based Student Health Survey (2003-2011)

INTRODUCTION

Based on a large cross-national dataset, we investigated the role of parental smoking (a risk factor) and parental supervision (a protective factor) on the frequency of smoking by youths in resource-poor countries. In addition, we tested for cross-level interactions between these two predictors and national wealth on the outcome variable.

METHODS

Pooled cross-sectional data from the Global School-based Student Health Survey (2003-2011) were analyzed, which consists of 58956 students in 31 countries. Hierarchical linear models were estimated to examine the associations between the two parental influence variables and adolescent smoking.

RESULTS

Among the control variables, age, gender (male), the experience of being bullied, frequency of getting into physical fights, truancy, and anxiety were significantly related to higher frequency of smoking. With respect to the main predictors, both at the individual level, parental supervision was negatively associated with adolescent smoking, while parental smoking was positively related to it. Two cross-level interaction terms were also observed. National wealth (GDP per capita) significantly moderated, that is, increased, these effects of parental influence on how often the adolescents smoked.

CONCLUSIONS

We provided new evidence on the factors related to adolescent smoking in low-income countries, a topic that has received very little attention. We showed that the associations between parental influences and adolescent smoking behaviors are not constant but vary according to the level of economic development. Future research should incorporate this comparative dimension in elaborating and specifying the conditions under which parental influences and other predictors differentially affect adolescent smoking.

IMPLICATIONS

Prior research on adolescent smoking focused on developed countries. Based on the secondary analysis of the Global School-based Student Health Survey (2003-2011), this study examines the associations between parental influence (parental smoking and parental supervision) on the frequency of youth smoking behaviors in resource-poor countries. We show that parental smoking is positively related to adolescent smoking, while parental supervision is negatively related to it. We also find that these two associations vary according to national wealth: both effects are stronger in a country with higher per capita GDP.

Emergence of sex differences in the development of substance use and abuse during adolescence

Substance use and abuse begin during adolescence. Male and female adolescent humans initiate use at comparable rates, but males increase use faster. In adulthood, more men than women use and abuse addictive drugs. However, some women progress more rapidly from initiation of use to entry into treatment. In animal models, adolescent males and females consume addictive drugs similarly. However, reproductively mature females acquire self-administration faster, and in some models, escalate use more. Sex/gender differences exist in neurobiologic factors mediating both reinforcement (dopamine, opioids) and aversiveness (CRF, dynorphin), as well as intrinsic factors (personality, psychiatric co-morbidities) and extrinsic factors (history of abuse, environment especially peers and family) which influence the progression from initial use to abuse. Many of these important differences emerge during adolescence, and are moderated by sexual differentiation of the brain. Estradiol effects which enhance both dopaminergic and CRF-mediated processes contribute to the female vulnerability to substance use and abuse. Testosterone enhances impulsivity and sensation seeking in both males and females. Several protective factors in females also influence initiation and progression of substance use including hormonal changes of pregnancy as well as greater capacity for self-regulation and lower peak levels of impulsivity/sensation seeking. Same sex peers represent a risk factor more for males than females during adolescence, while romantic partners increase risk for women during this developmental epoch. In summary, biologic factors, psychiatric co-morbidities as well as personality and environment present sex/gender-specific risks as adolescents begin to initiate substance use.

Tobacco control environment in the United States and individual consumer characteristics in relation to continued smoking: differential responses among menthol smokers?

OBJECTIVE

We used a consumer panel augmented with state-specific measures of tobacco control activities to examine the main effects and interactions among consumer behaviors, particularly menthol cigarette smoking, and tobacco control environment on cessation over a six-year period.

METHODS

We used the Nielson Homescan Panel, which tracks consumer purchasing behaviors, and tobacco control information matched to panelist zip code. We focused on 1582 households purchasing ≥20 packs from 2004 to 2009. Our analysis included demographics; purchasing behavior including menthol versus nonmenthol use (≥80% of cigarettes purchased being menthol), quality preferences (average price/pack), purchase recency, and nicotine intake (nicotine levels of cigarettes purchased); and tobacco control metrics (taxation, anti-tobacco advertising, smoke-free policies).

RESULTS

Menthol smoking (Hazard Ratio [HR]=0.79, 95% Confidence Interval [CI] 0.64, 0.99), being African American (HR=0.67, CI 0.46, 0.98), being male (HR=0.46, CI 0.28, 0.74), higher quality premium preferences (HR=0.80, CI 0.77, 0.91), lower recency (HR=1.04, CI 1.02, 1.05), and higher nicotine intake rates (HR=0.99, CI 0.99, 0.99) were related to continued smoking. No significant interactions were found.

CONCLUSION

While there were no interactions between menthol use and effects of tobacco control activities, we did find additional support for the decreased cessation rates among menthol cigarette smokers, particularly in the African American population.

Intent to quit among daily and non-daily college student smokers

Given the high prevalence of young adult smoking, we examined (i) psychosocial factors and substance use among college students representing five smoking patterns and histories [non-smokers, quitters, native non-daily smokers (i.e. never daily smokers), converted non-daily smokers (i.e. former daily smokers) and daily smokers] and (ii) smoking category as it relates to readiness to quit among current smokers. Of the 4438 students at six Southeast colleges who completed an online survey, 69.7% (n = 3094) were non-smokers, 6.6% (n = 293) were quitters, 7.1% (n = 317) were native non-daily smokers, 6.4% (n = 283) were converted non-daily smokers and 10.2% (n = 451) were daily smokers. There were differences in sociodemographics, substance use (alcohol, marijuana, other tobacco products) in the past 30 days and psychosocial factors among these subgroups of students (P < 0.001). Among current smokers, there were differences in cigarettes smoked per day, recent quit attempts, self-identification as a smoker, self-efficacy and motivation to quit (P < 0.001). After controlling for important factors, converted non-daily smokers were more likely to be ready to quit in the next month versus native non-daily smokers (OR = 2.15, CI 1.32-3.49, P = 0.002). Understanding differences among young adults with different smoking patterns and histories is critical in developing interventions targeting psychosocial factors impacting cessation among this population.

Environmental tobacco smoke avoidance among pregnant African-American nonsmokers

BACKGROUND

Environmental tobacco smoke (ETS) exposure during pregnancy contributes to adverse infant health outcomes. Limited previous research has focused on identifying correlates of ETS avoidance. This study sought to identify proximal and more distal correlates of ETS avoidance early in pregnancy among African-American women.

METHODS

From a sample of low-income, black women (n=1044) recruited in six urban, prenatal care clinics (July 2001-October 2003), cotinine-confirmed nonsmokers with partners, household/family members, or friends who smoked (n=450) were identified and divided into two groups: any past-7-day ETS exposure and cotinine-confirmed ETS avoidance. Bivariate and multivariate logistic regression analyses identified factors associated with ETS avoidance. Data were initially analyzed in 2004. Final models were reviewed and revised in 2007 and 2008.

RESULTS

Twenty-seven percent of pregnant nonsmokers were confirmed as ETS avoiders. In multivariate logistic regression analysis, the odds of ETS avoidance were increased among women who reported household smoking bans (OR=2.96; 95% CI=1.83, 4.77; p<0.0001), that the father wanted the baby (OR=2.70; CI=1.26, 5.76; p=0.01), and that no/few family members/friends smoked (OR=3.15; 95% CI=1.58, 6.29; p<0.001). The odds were decreased among women who had a current partner (OR=0.42; 95% CI=0.23, 0.76; p<0.01), reported any intimate partner violence during pregnancy (OR=0.43; 95% CI=0.19, 0.95; p<0.05), and reported little social support to prevent ETS exposure (OR=0.50; 95% CI=0.30, 0.85; p=0.01). Parity, emotional coping strategies, substance use during pregnancy, partner/household member smoking status, and self-confidence in avoiding ETS were significant in bivariate, but not multivariate analyses.

CONCLUSIONS

Social contextual factors were the strongest determinants of ETS avoidance during pregnancy. Results highlight the importance of prenatal screening to identify pregnant nonsmokers at risk, encouraging household smoking bans, gaining support from significant others, and fully understanding the interpersonal context of a woman's pregnancy before providing behavioral counseling and advice to prevent ETS exposure.

Emergent cigarette smoking, correlations with depression and interest in cessation among Aboriginal adolescents in British Columbia

OBJECTIVES

To describe smoking rates, age of initiation, and smoking cessation efforts among Aboriginal adolescent girls and boys in British Columbia, and examine the relationships between cigarette smoking and socio-demographic characteristics, depression and domains of life satisfaction.

METHODS

A secondary analysis was conducted of data collected from the British Columbia Youth Survey on Smoking and Health II measuring demographic and social factors, previous smoking experience, life satisfaction and depression. Data were analyzed from respondents who self-identified as Aboriginal, and by gender. Logistic regression models were used to identify risk factors for current cigarette smoking.

RESULTS

The average age of respondents was 15 years (SD=1.7) and 51% were female. Current cigarette smoking was 31%, with a mean age of initiation to smoking of 11 years (SD=3). On average, smokers consumed 3.8 cigarettes each day (SD=5.7), with most smokers (78%) reporting that they had seriously thought about quitting. More girls smoked than boys but girls smoked fewer cigarettes. As depression scores (CESD) increased, so did smoking among respondents; and as life satisfaction decreased, smoking increased. Having a best friend who smokes was the most powerful predictor of current smoking, increasing the odds of being a smoker by a factor of 5.9.

DISCUSSION

Although rates of tobacco smoking among respondents are high, there is considerable interest in cessation among current smokers. Recognizing that these youth are motivated to quit smoking, cessation programs may increase success by addressing peer smoking in prevention and cessation initiatives and including culturally appropriate strategies to promote mental health.

Racially classified social group tobacco-related health disparities: what is the role of genetics?

Certain racially classified social groups suffer disproportionately from tobacco-caused morbidity and mortality. Recent advances in genetics are leading researchers to examine variables that may account for this. However, it is critical that investigators proceed with caution and utilize transdisciplinary approaches. A number of fundamental questions might be used to stimulate consensus building in this area of science. What is race and how should its complexity be operationalized? Is it possible/likely that pharmacogenetics will allow us to match smokers with cessation strategies based on a gene-psychological profile? What are the most important conceptual and methodological issues for a research agenda in this area?

KLOTHO allele status and the risk of early-onset occult coronary artery disease

We previously identified a functional variant of KLOTHO (termed "KL-VS"), which harbors two amino acid substitutions in complete linkage disequilibrium and is associated with reduced human longevity when in homozygosity. Klotho-deficient mice display extensive arteriosclerosis when fed a normal diet, suggesting a potent genetic predisposition. To determine whether klotho influences atherosclerotic risk in humans, we performed cross-sectional studies to assess the association between the KL-VS allele and occult coronary artery disease (CAD) in two independent samples of apparently healthy siblings of individuals with early-onset (age <60 years) CAD (SIBS-I [N=520] and SIBS-II [N=436]). Occult CAD was defined as the occurrence of a reversible perfusion defect during exercise thallium scintigraphy and/or as an abnormal result of an exercise electrocardiogram (SIBS-I, n=97; SIBS-II, n=56). In SIBS-I, the KL-VS allele conferred a relative odds of 1.90 (95% confidence interval 1.21-2.98) for occult CAD, after adjusting for familial intraclass correlations (P<.005). Logistic regression modeling, incorporating known CAD risk factors, demonstrated that the KL-VS allele is an independent risk factor (P<.019) and that the imposed risk of KL-VS allele status is influenced by modifiable risk factors. Hypertension (P<.022) and increasing high-density lipoprotein cholesterol (HDL-C) levels (P<.022) mask or reduce the risk conferred by the KL-VS allele, respectively, whereas current smoking (P<.004) increases the risk. Remarkably concordant effects of the KL-VS allele and modifying factors on the risk of occult CAD were seen in SIBS-II. These results demonstrate that the KL-VS allele is an independent risk factor for occult CAD in two independent high-risk samples. Modifiable risk factors, including hypertension, smoking status, and HDL-C level, appear to influence the risk imposed by this allele.