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1.  Calcyon mRNA expression in the frontal-striatal circuitry and its relationship to vesicular processes and ADHD 
Calcyon is a single transmembrane protein predominantly expressed in the brain. Very recently, calcyon has been implicated in clathrin mediated endocytosis, a critical component of synaptic plasticity. At the genetic level, preliminary evidence supports an association between attention-deficit/hyperactivity disorder (ADHD) and polymorphisms in the calcyon gene. As little is known about the potential role of calcyon in ADHD, animal models may provide important insights into this issue.
We examined calcyon mRNA expression in the frontal-striatal circuitry of three-, five-, and ten-week-old Spontaneously Hypertensive Rats (SHR), the most commonly used animal model of ADHD, and Wistar-Kyoto (WKY; the strain from which SHR were derived). As a complement, we performed a co-expression network analysis using a database of mRNA gene expression profiles of multiple brain regions in order to explore potential functional links of calcyon to other genes.
In all age groups, SHR expressed significantly more calcyon mRNA in the medial prefrontal and orbital frontal cortices than WKY rats. In contrast, in the motor cortex, dorsal striatum and nucleus accumbens, calcyon mRNA expression was only significantly elevated in SHR in younger animals. In both strains, calcyon mRNA levels decreased significantly with age in all regions studied. In the co-expression network analysis, we found a cluster of genes (many of them poorly studied so far) strongly connected to calcyon, which may help elucidate its role in the brain. The pair-wise relations of calcyon with other genes support its involvement in clathrin mediated endocytosis and, potentially, some other membrane/vesicular processes. Interestingly, no link was found between calcyon and the dopamine D1 receptor, which was previously shown to interact with the C-terminal of calcyon.
The results indicate an alteration in calcyon expression within the frontal-striatal circuitry of SHR, especially in areas involved in cognitive processes. These findings extend our understanding of the molecular alterations in SHR, a heuristically useful model of ADHD.
PMCID: PMC1949817  PMID: 17623072
2.  Active or Passive Exposure to Tobacco Smoking and Allergic Rhinitis, Allergic Dermatitis, and Food Allergy in Adults and Children: A Systematic Review and Meta-Analysis 
PLoS Medicine  2014;11(3):e1001611.
In a systematic review and meta-analysis, Bahi Takkouche and colleagues examine the associations between exposure to tobacco smoke and allergic disorders in children and adults.
Please see later in the article for the Editors' Summary
Allergic rhinitis, allergic dermatitis, and food allergy are extremely common diseases, especially among children, and are frequently associated to each other and to asthma. Smoking is a potential risk factor for these conditions, but so far, results from individual studies have been conflicting. The objective of this study was to examine the evidence for an association between active smoking (AS) or passive exposure to secondhand smoke and allergic conditions.
Methods and Findings
We retrieved studies published in any language up to June 30th, 2013 by systematically searching Medline, Embase, the five regional bibliographic databases of the World Health Organization, and ISI-Proceedings databases, by manually examining the references of the original articles and reviews retrieved, and by establishing personal contact with clinical researchers. We included cohort, case-control, and cross-sectional studies reporting odds ratio (OR) or relative risk (RR) estimates and confidence intervals of smoking and allergic conditions, first among the general population and then among children.
We retrieved 97 studies on allergic rhinitis, 91 on allergic dermatitis, and eight on food allergy published in 139 different articles. When all studies were analyzed together (showing random effects model results and pooled ORs expressed as RR), allergic rhinitis was not associated with active smoking (pooled RR, 1.02 [95% CI 0.92–1.15]), but was associated with passive smoking (pooled RR 1.10 [95% CI 1.06–1.15]). Allergic dermatitis was associated with both active (pooled RR, 1.21 [95% CI 1.14–1.29]) and passive smoking (pooled RR, 1.07 [95% CI 1.03–1.12]). In children and adolescent, allergic rhinitis was associated with active (pooled RR, 1.40 (95% CI 1.24–1.59) and passive smoking (pooled RR, 1.09 [95% CI 1.04–1.14]). Allergic dermatitis was associated with active (pooled RR, 1.36 [95% CI 1.17–1.46]) and passive smoking (pooled RR, 1.06 [95% CI 1.01–1.11]). Food allergy was associated with SHS (1.43 [1.12–1.83]) when cohort studies only were examined, but not when all studies were combined.
The findings are limited by the potential for confounding and bias given that most of the individual studies used a cross-sectional design. Furthermore, the studies showed a high degree of heterogeneity and the exposure and outcome measures were assessed by self-report, which may increase the potential for misclassification.
We observed very modest associations between smoking and some allergic diseases among adults. Among children and adolescents, both active and passive exposure to SHS were associated with a modest increased risk for allergic diseases, and passive smoking was associated with an increased risk for food allergy. Additional studies with detailed measurement of exposure and better case definition are needed to further explore the role of smoking in allergic diseases.
Please see later in the article for the Editors' Summary
Editors' Summary
The immune system protects the human body from viruses, bacteria, and other pathogens. Whenever a pathogen enters the body, immune system cells called T lymphocytes recognize specific molecules on its surface and release chemical messengers that recruit and activate other types of immune cells, which then attack the pathogen. Sometimes, however, the immune system responds to harmless materials (for example, pollen; scientists call these materials allergens) and triggers an allergic disease such as allergic rhinitis (inflammation of the inside of the nose; hay fever is a type of allergic rhinitis), allergic dermatitis (also known as eczema, a disease characterized by dry, itchy patches on the skin), and food allergy. Recent studies suggest that all these allergic (atopic) diseases are part of a continuous state called the “atopic march” in which individuals develop allergic diseases in a specific sequence that starts with allergic dermatitis during infancy, and progresses to food allergy, allergic rhinitis, and finally asthma (inflammation of the airways).
Why Was This Study Done?
Allergic diseases are extremely common, particularly in children. Allergic rhinitis alone affects 10%–30% of the world's population and up to 40% of children in some countries. Moreover, allergic diseases are becoming increasingly common. Allergic diseases affect the quality of life of patients and are financially costly to both patients and health systems. It is important, therefore, to identify the factors that cause or potentiate their development. One potential risk factor for allergic diseases is active or passive exposure to tobacco smoke. In some countries up to 80% of children are exposed to second-hand smoke so, from a public health point of view, it would be useful to know whether exposure to tobacco smoke is associated with the development of allergic diseases. Here, the researchers undertake a systematic review (a study that uses predefined criteria to identify all the research on a given topic) and a meta-analysis (a statistical approach for combining the results of several studies) to investigate this issue.
What Did the Researchers Do and Find?
The researchers identified 196 observational studies (investigations that observe outcomes in populations without trying to affect these outcomes in any way) that examined the association between smoke exposure and allergic rhinitis, allergic dermatitis, or food allergy. When all studies were analyzed together, allergic rhinitis was not associated with active smoking but was slightly associated with exposure to second-hand smoke. Specifically, compared to people not exposed to second-hand smoke, the pooled relative risk (RR) of allergic rhinitis among people exposed to second-hand smoke was 1.10 (an RR of greater than 1 indicates an increased risk of disease development in an exposed population compared to an unexposed population). Allergic dermatitis was associated with both active smoking (RR = 1.21) and exposure to second-hand smoke (RR = 1.07). In the populations of children and adolescents included in the studies, allergic rhinitis was associated with both active smoking and exposure to second-hand smoke (RRs of 1.40 and 1.09, respectively), as was allergic dermatitis (RRs of 1.36 and 1.06, respectively). Finally food allergy was associated with exposure to second-hand smoke (RR = 1.43) when cohort studies (a specific type of observational study) only were examined but not when all the studies were combined.
What Do These Findings Mean?
These findings provide limited evidence for a weak association between smoke exposure and allergic disease in adults but suggest that both active and passive smoking are associated with a modestly increased risk of allergic diseases in children and adolescents. The accuracy of these findings may be affected by the use of questionnaires to assess smoke exposure and allergic disease development in most of the studies in the meta-analysis and by the possibility that individuals exposed to smoke may have shared other characteristics that were actually responsible for their increased risk of allergic diseases. To shed more light on the role of smoking in allergic diseases, additional studies are needed that accurately measure exposure and outcomes. However, the present findings suggest that, in countries where many people smoke, 14% and 13% of allergic rhinitis and allergic dermatitis, respectively, among children may be attributable to active smoking. Thus, the elimination of active smoking among children and adolescents could prevent one in seven cases of allergic rhinitis and one in eight cases of allergic dermatitis in such countries.
Additional Information
Please access these websites via the online version of this summary at
The UK National Health Service Choices website provides information about allergic rhinitis, hay fever (including personal stories), allergic dermatitis (including personal stories), and food allergy (including personal stories)
The US National Institute of Allergy and Infectious Disease provides information about allergic diseases
The UK not-for-profit organization Allergy UK provides information about all aspects of allergic diseases and a description of the atopic march
MedlinePlus encyclopedia has pages on allergic rhinitis and allergic dermatitis (in English and Spanish)
MedlinePlus provides links to further resources about allergies, eczema, and food allergy (in English and Spanish)
PMCID: PMC3949681  PMID: 24618794
3.  Burden of Total and Cause-Specific Mortality Related to Tobacco Smoking among Adults Aged ≥45 Years in Asia: A Pooled Analysis of 21 Cohorts 
PLoS Medicine  2014;11(4):e1001631.
Wei Zheng and colleagues quantify the burden of tobacco-smoking-related deaths for adults in Asia.
Please see later in the article for the Editors' Summary
Tobacco smoking is a major risk factor for many diseases. We sought to quantify the burden of tobacco-smoking-related deaths in Asia, in parts of which men's smoking prevalence is among the world's highest.
Methods and Findings
We performed pooled analyses of data from 1,049,929 participants in 21 cohorts in Asia to quantify the risks of total and cause-specific mortality associated with tobacco smoking using adjusted hazard ratios and their 95% confidence intervals. We then estimated smoking-related deaths among adults aged ≥45 y in 2004 in Bangladesh, India, mainland China, Japan, Republic of Korea, Singapore, and Taiwan—accounting for ∼71% of Asia's total population. An approximately 1.44-fold (95% CI = 1.37–1.51) and 1.48-fold (1.38–1.58) elevated risk of death from any cause was found in male and female ever-smokers, respectively. In 2004, active tobacco smoking accounted for approximately 15.8% (95% CI = 14.3%–17.2%) and 3.3% (2.6%–4.0%) of deaths, respectively, in men and women aged ≥45 y in the seven countries/regions combined, with a total number of estimated deaths of ∼1,575,500 (95% CI = 1,398,000–1,744,700). Among men, approximately 11.4%, 30.5%, and 19.8% of deaths due to cardiovascular diseases, cancer, and respiratory diseases, respectively, were attributable to tobacco smoking. Corresponding proportions for East Asian women were 3.7%, 4.6%, and 1.7%, respectively. The strongest association with tobacco smoking was found for lung cancer: a 3- to 4-fold elevated risk, accounting for 60.5% and 16.7% of lung cancer deaths, respectively, in Asian men and East Asian women aged ≥45 y.
Tobacco smoking is associated with a substantially elevated risk of mortality, accounting for approximately 2 million deaths in adults aged ≥45 y throughout Asia in 2004. It is likely that smoking-related deaths in Asia will continue to rise over the next few decades if no effective smoking control programs are implemented.
Please see later in the article for the Editors' Summary
Editors' Summary
Every year, more than 5 million smokers die from tobacco-related diseases. Tobacco smoking is a major risk factor for cardiovascular disease (conditions that affect the heart and the circulation), respiratory disease (conditions that affect breathing), lung cancer, and several other types of cancer. All told, tobacco smoking kills up to half its users. The ongoing global “epidemic” of tobacco smoking and tobacco-related diseases initially affected people living in the US and other Western countries, where the prevalence of smoking (the proportion of the population that smokes) in men began to rise in the early 1900s, peaking in the 1960s. A similar epidemic occurred in women about 40 years later. Smoking-related deaths began to increase in the second half of the 20th century, and by the 1990s, tobacco smoking accounted for a third of all deaths and about half of cancer deaths among men in the US and other Western countries. More recently, increased awareness of the risks of smoking and the introduction of various tobacco control measures has led to a steady decline in tobacco use and in smoking-related diseases in many developed countries.
Why Was This Study Done?
Unfortunately, less well-developed tobacco control programs, inadequate public awareness of smoking risks, and tobacco company marketing have recently led to sharp increases in the prevalence of smoking in many low- and middle-income countries, particularly in Asia. More than 50% of men in many Asian countries are now smokers, about twice the prevalence in many Western countries, and more women in some Asian countries are smoking than previously. More than half of the world's billion smokers now live in Asia. However, little is known about the burden of tobacco-related mortality (deaths) in this region. In this study, the researchers quantify the risk of total and cause-specific mortality associated with tobacco use among adults aged 45 years or older by undertaking a pooled statistical analysis of data collected from 21 Asian cohorts (groups) about their smoking history and health.
What Did the Researchers Do and Find?
For their study, the researchers used data from more than 1 million participants enrolled in studies undertaken in Bangladesh, India, mainland China, Japan, the Republic of Korea, Singapore, and Taiwan (which together account for 71% of Asia's total population). Smoking prevalences among male and female participants were 65.1% and 7.1%, respectively. Compared with never-smokers, ever-smokers had a higher risk of death from any cause in pooled analyses of all the cohorts (adjusted hazard ratios [HRs] of 1.44 and 1.48 for men and women, respectively; an adjusted HR indicates how often an event occurs in one group compared to another group after adjustment for other characteristics that affect an individual's risk of the event). Compared with never smoking, ever smoking was associated with a higher risk of death due to cardiovascular disease, cancer (particularly lung cancer), and respiratory disease among Asian men and among East Asian women. Moreover, the researchers estimate that, in the countries included in this study, tobacco smoking accounted for 15.8% of all deaths among men and 3.3% of deaths among women in 2004—a total of about 1.5 million deaths, which scales up to 2 million deaths for the population of the whole of Asia. Notably, in 2004, tobacco smoking accounted for 60.5% of lung-cancer deaths among Asian men and 16.7% of lung-cancer deaths among East Asian women.
What Do These Findings Mean?
These findings provide strong evidence that tobacco smoking is associated with a substantially raised risk of death among adults aged 45 years or older throughout Asia. The association between smoking and mortality risk in Asia reported here is weaker than that previously reported for Western countries, possibly because widespread tobacco smoking started several decades later in most Asian countries than in Europe and North America and the deleterious effects of smoking take some years to become evident. The researchers note that certain limitations of their analysis are likely to affect the accuracy of its findings. For example, because no data were available to estimate the impact of secondhand smoke, the estimate of deaths attributable to smoking is likely to be an underestimate. However, the finding that nearly 45% of the global deaths from active tobacco smoking occur in Asia highlights the urgent need to implement comprehensive tobacco control programs in Asia to reduce the burden of tobacco-related disease.
Additional Information
Please access these websites via the online version of this summary at
The World Health Organization provides information about the dangers of tobacco (in several languages) and about the WHO Framework Convention on Tobacco Control, an international instrument for tobacco control that came into force in February 2005 and requires parties to implement a set of core tobacco control provisions including legislation to ban tobacco advertising and to increase tobacco taxes; its 2013 report on the global tobacco epidemic is available
The US Centers for Disease Control and Prevention provides detailed information about all aspects of smoking and tobacco use
The UK National Health Services Choices website provides information about the health risks associated with smoking
MedlinePlus has links to further information about the dangers of smoking (in English and Spanish)
SmokeFree, a website provided by the UK National Health Service, offers advice on quitting smoking and includes personal stories from people who have stopped smoking, from the US National Cancer Institute, offers online tools and resources to help people quit smoking
PMCID: PMC3995657  PMID: 24756146
4.  Evaluating Depressive Symptom Interactions on Adolescent Smoking Prevention Program Mediators: A Mediated Moderation Analysis 
Nicotine & Tobacco Research  2010;12(11):1099-1107.
Smoking prevention interventions have been shown to be effective in reducing smoking prevalence in the United States. Further work is needed to address smoking in China, where over one third of the world’s current smokers reside. China, with more than 60% of the male population being smokers, also presents a unique opportunity to test cognitive processes involved in depression, social influences, and smoking. Adolescents at-risk for developing depression may process social information differently from low-risk counterparts.
The Wuhan Smoking Prevention Trial was a school-based longitudinal randomized controlled trial aimed at preventing initiation and escalation of adolescent smoking behaviors. Thousand three hundred and ninety-one male seventh-grade students were assessed with a 200-item paper-and-pencil baseline survey, and it was readministered 1 year later following program implementation.
Friend prevalence estimates were significantly higher among 30-day smokers and among those at highest risk for depression symptoms. The program appeared to be successful in changing the perception of friend smoking prevalence only among adolescents with a comorbidity of high scores of depression symptoms and who have experimented previously with smoking. This Program × Comorbidity interaction on perceived friend smoking prevalence was significant in predicting 30-day smoking 1 year after program implementation.
This study provides evidence that those adolescents with high levels of depressive symptoms may be more sensitive to social influences associated with smoking prevalence. Individual Disposition × Social Environmental Influences may be important when developing future effective prevention programming.
PMCID: PMC2964921  PMID: 20861150
5.  Calcyon Up-regulation in Adolescence Impairs Response Inhibition and Working Memory in Adulthood 
Molecular psychiatry  2011;16(6):672-684.
Calcyon regulates activity dependent internalization of AMPA glutamate receptors and long term depression of excitatory synapses. Elevated levels of calcyon are consistently observed in brains from schizophrenic patients, and the calcyon gene is associated with attention deficit hyperactivity disorder. Executive function deficits are common to both disorders, and at least for schizophrenia, the etiology appears to involve both heritable and neurodevelopmental factors. Here, we show with calcyon overexpressing CalOE transgenic mice that lifelong calcyon upregulation impairs executive functions including response inhibition and working memory, without producing learning and memory deficits in general. As response inhibition and working memory, as well as the underlying neural circuitry continue to mature into early adulthood, we functionally silenced the transgene during postnatal days 28–49, a period corresponding to adolescence. Remarkably, the response inhibition and working memory deficits including perseverative behavior were absent in adult CalOE mice with the transgene silenced in adolescence. Suppressing the calcyon transgene in adulthood only partially rescued the deficits, suggesting calcyon upregulation in adolescence irreversibly alters development of neural circuits supporting mature response inhibition and working memory. Brain regional immunoblots revealed a prominent down-regulation of AMPA GluR1 subunits in hippocampus, and GluR2/3 subunits in hippocampus and prefrontal cortex of the CalOE mice. Silencing the transgene in adolescence prevented the decrease in hippocampal GluR1, further implicating altered frontohippocampal connectivity in the executive function deficits observed in the CalOE mice. Treatments that mitigate the effects of high levels of calcyon during adolescence could preempt adult deficits in executive functions in individuals at-risk for serious mental illness.
PMCID: PMC4076415  PMID: 21403673
schizophrenia; ADHD; mice; fear conditioning; watermaze; working memory; executive functions
6.  Perceived importance of being thin and smoking initiation among young girls 
Tobacco Control  2003;12(3):289-295.
Background: Smoking among adolescents remains unacceptably high and the difference in potential risk factors for smoking initiation between male and female adolescents has been explored. Although the association between smoking initiation and dieting behaviour has been observed among girls, the mechanism of the association is unknown.
Objective: To examine prospectively the association between perceived importance of being thin at baseline and smoking initiation among girls.
Design: A four year prospective cohort survey including perceived importance of being thin at baseline and smoking behaviour, conducted in 1993 and 1996.
Setting and participants: 273 Massachusetts female adolescents aged 12–15 years at baseline who reported having smoked no more than one cigarette by the time of the baseline survey, drawn from households sampled by random digit dialling.
Main outcome measure: Progression to established smoking, defined as having smoked 100 or more cigarettes in their lifetime.
Results: After adjusting for age, smoking status at baseline, and race/ethnicity, girls who valued thinness most strongly and somewhat strongly were both more likely to have become established smokers, compared to the girls who valued thinness least strongly. The odds ratios are 4.5 (95% confidence interval (CI), 1.4 to 16.7) and 3.4 (95% CI 1.04 to 10.9), respectively.
Conclusions: The level of perceived importance of being thin among young female adolescents predicts future smoking initiation. Smoking prevention programmes designed for female adolescents may therefore benefit from the inclusion of content related to importance of being thin.
PMCID: PMC1747738  PMID: 12958390
7.  Regular Smoking and Asthma Incidence in Adolescents 
Rationale: Although involuntary exposure to maternal smoking during the in utero period and to secondhand smoke are associated with occurrence of childhood asthma, few studies have investigated the role of active cigarette smoking on asthma onset during adolescence.
Objectives: To determine whether regular smoking is associated with the new onset of asthma during adolescence.
Methods: We conducted a prospective cohort study among 2,609 children with no lifetime history of asthma or wheezing who were recruited from fourth- and seventh-grade classrooms and followed annually in schools in 12 southern California communities. Regular smoking was defined as smoking at least seven cigarettes per day on average over the week before and 300 cigarettes in the year before each annual interview. Incident asthma was defined using new cases of physician-diagnosed asthma.
Measurements and Main Results: Regular smoking was associated with increased risk of new-onset asthma. Children who reported smoking 300 or more cigarettes per year had a relative risk (RR) of 3.9 (95% confidence interval [95% CI], 1.7–8.5) for new-onset asthma compared with nonsmokers. The increased risk from regular smoking was greater in nonallergic than in allergic children. Regular smokers who were exposed to maternal smoking during gestation had the largest risk from active smoking (RR, 8.8; 95% CI, 3.2–24.0).
Conclusions: Regular smoking increased risk for asthma among adolescents, especially for nonallergic adolescents and those exposed to maternal smoking during the in utero period.
PMCID: PMC2648110  PMID: 16973983
asthma; epidemiology; smoking
8.  Developmental Trajectories of Cigarette Use and Associations With Multilayered Risk Factors Among Chinese Adolescents 
Nicotine & Tobacco Research  2013;15(10):1673-1681.
We aimed to identify developmental trajectories of cigarette use and risk factors associated with the distinct developmental courses of smoking in Chinese early adolescents from age 12 to 16 years.
Analysis was conducted with secondary data from a longitudinal, prospective cohort of 3,521 Chinese adolescents randomly selected from 4 rural and 7 urban middle schools in Wuhan, China. A group-based growth mixture modeling approach was adopted to identify developmental trajectories of cigarette use. Multilayered intrapersonal (e.g., attitudes toward smoking) and interpersonal (e.g., parental smoking and perceived parental disapproval of smoking) risk factors selected from an ecological perspective were prospectively linked to the identified patterns of smoking trajectory.
Three trajectory patterns were identified from the whole cohort: nonsmokers (48.7%), stable light/occasional smokers (48.6%), and accelerating smokers (2.7%). After adjustments for gender, urban residence, and family socioeconomic status, adolescents with higher levels of problems in parent–child relationships and family disharmony, higher perceived norms of peer smoking, higher proportion of good friend smoking, having more troubles with teachers, poorer academic performance, and reporting more frequent depressive symptoms were significantly more likely to be in the trajectory group of either stable light/occasional smokers or accelerating smokers than in the group of nonsmokers. The probability of being in the accelerating smoking trajectory group was positively and significantly related to parental smoking and lack of school bonding.
Study findings help to advance knowledge of the distinct developmental courses of smoking behavior and their associations with multilayered risk factors among Chinese early adolescents.
PMCID: PMC3768331  PMID: 23525597
9.  Effect of the California Tobacco Control Program on Personal Health Care Expenditures 
PLoS Medicine  2008;5(8):e178.
Large state tobacco control programs have been shown to reduce smoking and would be expected to affect health care costs. We investigate the effect of California's large-scale tobacco control program on aggregate personal health care expenditures in the state.
Methods and Findings
Cointegrating regressions were used to predict (1) the difference in per capita cigarette consumption between California and 38 control states as a function of the difference in cumulative expenditures of the California and control state tobacco control programs, and (2) the relationship between the difference in cigarette consumption and the difference in per capita personal health expenditures between the control states and California between 1980 and 2004. Between 1989 (when it started) and 2004, the California program was associated with $86 billion (2004 US dollars) (95% confidence interval [CI] $28 billion to $151 billion) lower health care expenditures than would have been expected without the program. This reduction grew over time, reaching 7.3% (95% CI 2.7%–12.1%) of total health care expenditures in 2004.
A strong tobacco control program is not only associated with reduced smoking, but also with reductions in health care expenditures.
Stanton Glantz and colleagues find that the California state tobacco control program is associated not only with reduced smoking, but with reductions in health care costs as well.
Editors' Summary
According to the World Health Organization (WHO), tobacco causes 1 in 10 adult deaths worldwide and is the leading preventable cause of death in the world. In 2005, tobacco caused 5.4 million deaths, which amounts to one death every 6 seconds. It is estimated that by 2030, annual deaths from tobacco use will be 8 million worldwide. Eighty percent of these deaths will occur in the developing world.
Exposure to secondhand tobacco smoke is also a major health concern, as it can cause cancer, heart disease, and respiratory illness. An estimated 200,000 workers die annually from exposure to smoke at work, according to the International Labour Organization.
In 2008, the WHO released a report on the global tobacco epidemic, which provided a comprehensive analysis of tobacco use and control efforts. It revealed that not a single country fully implements all key tobacco control measures. The report also stated that governments around the world collect 500 times more money in tobacco taxes each year than they spend on anti-tobacco efforts.
The California Tobacco Control Program (CTCP) is a state-funded public policy intervention established in 1989. Its goal is to decrease tobacco-related diseases and deaths in California by reducing tobacco use across the state. The program is focused on adults and social norm change rather than on adolescent tobacco use prevention, on the premise that the “next generation cannot be saved without changing the generations who have already reached adulthood.”
Why Was This Study Done?
The success of large public health programs, especially those that counter the tactics of powerful industries such as the tobacco industry, require funding. The justification of public spending on these initiatives should be evidence driven. While the success of the CTCP in reducing smoking was known, it was not yet clear whether the program had reduced health care costs. The researchers investigated the effect of the CTCP on personal health care expenditures in the state. Their findings can provide useful information for the development of other tobacco control initiatives.
What Did the Researchers Do and Find?
Using the statistical approach of cointegrating regressions, the researchers modeled the relationships between per capita tobacco control expenditures, per capita cigarette consumption, and health care expenditures. They analyzed data from 1980 and 2004 on smoking, health care expenditures, and exposure to a tobacco control educational program in California and compared them to a group of 38 control states. Control states were those without comprehensive tobacco control programs prior to 2000 or cigarette tax increases of $0.50 or more per pack over the study period. This comparison allowed the researchers to assess the effect of the CTCP on total personal health care spending.
The researchers found that US$86 billion (95% CI $28 billion to $151 billion) were saved in personal health care expenditure between 1989, the start of the program, and 2004. This generally grew over time, reaching 7.3% of the total in 2003–2004. The personal health care expenditure savings represented about a 50-fold return on the $1.8 billion spent on the program during the same period (all 2004 US dollars).
The researchers report that 3.6 billion (95% CI 1.5 billion to 5.9 billion) fewer packs of cigarettes were sold between 1989–1990 and 2003–2004. This represents a loss of $9.2 billion (95% CI $3.8 billion to $14.7 billion) to the tobacco industry in pre-tax cigarette sales.
These cost savings occurred despite the substantial diversion of funding and decreased purchasing power experienced by the CTCP, particularly in the mid-1990s. (The program was funded with a constant tax of $0.05 per pack, despite inflation). The researchers estimated that if the funding, and thus purchasing power, had been maintained, total savings in personal health expenditures would have increased to $156 billion with an additional $70 billion in health cost savings. Cigarette consumption would have dropped to an estimated 6.6 billion packs.
What Do These Findings Mean?
The CTCP has been successful in reducing smoking in California in comparison to other states, and has reduced personal health care expenditures. These cost reductions were substantial, rapid, and grew over time. The researchers contend that the CTCP's focus on social norm change among adults, not primarily on youth prevention, is responsible for such rapid and large reductions in disease and the associated health care costs. They state that a program focused on primary prevention of smoking among adolescents would take decades to have any impact on tobacco-induced diseases, which rarely manifest among adolescents or even young adults. These researcher's findings support the establishment of strong tobacco control programs in other settings: they not only reduce smoking, prevent disease, and save lives, but also represent an important way to curb rapidly increasing health care expenditures in the short term.
Additional Information.
Please access these Web sites via the online version of this summary at
The California Tobacco Control Program provides information about its social change approach
The WHO MPOWER strategy, detailed in the 2008 Report on the Global Tobacco Epidemic, outlines the six most effective policies to help curb the epidemic
Resources to help people quit smoking can be obtained through the US Centers for Disease Control and the UK National Health Service
PMCID: PMC2522256  PMID: 18752344
10.  A Candidate Gene Approach Identifies the CHRNA5-A3-B4 Region as a Risk Factor for Age-Dependent Nicotine Addiction 
PLoS Genetics  2008;4(7):e1000125.
People who begin daily smoking at an early age are at greater risk of long-term nicotine addiction. We tested the hypothesis that associations between nicotinic acetylcholine receptor (nAChR) genetic variants and nicotine dependence assessed in adulthood will be stronger among smokers who began daily nicotine exposure during adolescence. We compared nicotine addiction—measured by the Fagerstrom Test of Nicotine Dependence—in three cohorts of long-term smokers recruited in Utah, Wisconsin, and by the NHLBI Lung Health Study, using a candidate-gene approach with the neuronal nAChR subunit genes. This SNP panel included common coding variants and haplotypes detected in eight α and three β nAChR subunit genes found in European American populations. In the 2,827 long-term smokers examined, common susceptibility and protective haplotypes at the CHRNA5-A3-B4 locus were associated with nicotine dependence severity (p = 2.0×10−5; odds ratio = 1.82; 95% confidence interval 1.39–2.39) in subjects who began daily smoking at or before the age of 16, an exposure period that results in a more severe form of adult nicotine dependence. A substantial shift in susceptibility versus protective diplotype frequency (AA versus BC = 17%, AA versus CC = 27%) was observed in the group that began smoking by age 16. This genetic effect was not observed in subjects who began daily nicotine use after the age of 16. These results establish a strong mechanistic link among early nicotine exposure, common CHRNA5-A3-B4 haplotypes, and adult nicotine addiction in three independent populations of European origins. The identification of an age-dependent susceptibility haplotype reinforces the importance of preventing early exposure to tobacco through public health policies.
Author Summary
Tobacco use is a global health care problem, and persistent smoking takes an enormous toll on individual health. The onset of daily smoking in adolescence is related to chronic use and severe nicotine dependence in adulthood. Since nicotine is the key addictive chemical in tobacco, we tested the hypothesis that genetic variants within nicotinic acetylcholine receptors will influence the severity of addiction measured in adulthood. Using genomic resequencing to define the patterns of variation found in these candidate genes, we observed that common haplotypes in the CHRNA5-A3-B4 gene cluster are associated with adult nicotine addiction, specifically among those who began daily smoking before age 17. We show that in populations of European origins, one haplotype is a risk factor for dependence, one is protective, and one is neutral. These observations suggest that genetic determinants expressed during human adolescence contribute to the risk of lifetime addiction severity produced from early onset of cigarette use. Because disease risk from the adverse health effects of tobacco smoke is related to lifetime tobacco exposure, the finding that an age-dependent effect of these haplotypes has a strong influence on lifetime smoking behavior reinforces the public health significance of delaying smoking onset.
PMCID: PMC2442220  PMID: 18618000
11.  One-year predictors of smoking initiation and of continued smoking among elementary schoolchildren in multiethnic, low-income, inner-city neighbourhoods 
Tobacco Control  1998;7(3):268-275.
OBJECTIVE—To identify one-year predictors of smoking initiation among never-smokers, and of continued smoking among ever-smokers.
DESIGN—Two sequential cohorts of grade 4 and 5 children. Data were collected as part of Coeur en sante St Louis du Parc, a non-randomised controlled trial to evaluate the impact of a school-based heart health promotion programme.
SETTING—24 inner-city elementary schools located in multiethnic, low-income neighbourhoods in Montreal.
SUBJECT—1824 schoolchildren aged 9-12 years with baseline and one-year follow-up data.
MAIN OUTCOME MEASURES—Changes in smoking behaviour over a year; the ability of baseline data to predict smoking initiation and continued smoking a year later was investigated in logistic regression analyses.
RESULTS—The prevalence of ever-smoking was 21.1% at baseline and 30.2% at one-year follow up. One in six never-smokers initiated smoking; one in three ever-smokers continued smoking. Predictors of initiation included age (odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.3 to 2.0), male gender (OR = 1.5 (95% CI = 1.1 to 2.0)), friends who smoke (OR = 2.3 (95% CI = 1.7 to 3.3)), sibling(s) who smoke (OR = 1.9 (95% CI = 1.2 to 3.1)), father/mother who smokes (OR = 2.2 (95% CI = 1.6 to 3.0)), and frequent high fat/"junk food" consumption (OR = 1.6 (95% CI = 1.1 to 2.1)). Age and friends who smoke were also independent predictors of continued smoking in both genders. In addition, in boys, current smokers at baseline were 2.6 times (95% CI = 1.4 to 5.0) more likely to continue smoking than past smokers. In girls, being overweight was associated with continued smoking (OR = 3.5 (95% CI = 1.6 to 7.6)).
CONCLUSIONS—Smoking prevention programmes should address parental and sibling influences on smoking, in addition to refusal skills training. Among girls, weight-related issues may also be important.

Keywords: children; smoking initiation predictors
PMCID: PMC1763870  PMID: 9825422
12.  Application of the Protection Motivation Theory in Predicting Cigarette Smoking Among Adolescents in China 
Addictive behaviors  2013;39(1):181-188.
Reducing tobacco use among adolescents in China represents a significant challenge for global tobacco control. Existing behavioral theories developed in the West – such as the Protection Motivation Theory (PMT) – may be useful tools to help tackle this challenge. We examined the relationships between PMT factors and self-reported cigarette smoking behavior and intention among a random sample of vocational high school students (N = 553) in Wuhan, China. Tobacco-related perceptions were assessed using the PMT Scale for Adolescent Smoking. Among the total sample, 45% had initiated cigarette smoking, and 25% smoked in the past month. Among those who never smoked, 15% indicated being likely or very likely to smoke in a year. Multiple regression modeling analysis indicated the significance of the seven PMT constructs, the four PMT perceptions and the two PMT pathways in predicting intention to smoke and actual smoking behavior. Overall, perceived rewards of smoking, especially intrinsic rewards, were consistently positively related to smoking intentions and behavior, and self-efficacy to avoid smoking was negatively related to smoking. The current study suggests the utility of PMT for further research examining adolescent smoking. PMT-based smoking prevention and clinical smoking cessation intervention programs should focus more on adolescents’ perceived rewards from smoking and perceived efficacy of not smoking to reduce their intention to and actual use of tobacco.
PMCID: PMC3966196  PMID: 24157424
Protection Motivation Theory; Adolescents; Cigarette smoking; China
13.  Perceptions of Second-hand Smoke Risks Predict Future Adolescent Smoking Initiation 
To directly test whether perceptions of second-hand smoke risks deter adolescent smoking initiation.
A longitudinal survey design was utilized in this study. Baseline surveys measuring perceptions of tobacco-related risks and smoking behaviors were administered to 395 high school students, with three follow-up assessments every 6 months.
Perceptions of personal second-hand smoke risks and parental second-hand smoke risks significantly deterred adolescent smoking initiation. Perceptions of personal second-hand smoke risks reduced the odds of smoking by a factor of 0.63 (95% confidence interval [CI] = 0.42–0.94) for each quartile increase in perceptions of personal second-hand smoke risks. Adolescents who provided the highest estimates of risks for personal second-hand smoke were 0.25 as likely to smoke as adolescents who provided the lowest estimates of risk. Perceptions of parental second-hand smoke risks reduced the odds of smoking by a factor of 0.64 (95% CI = 0.43–0.93) for each quartile increase. Adolescents who perceived the highest estimates of risks associated with parental second-hand smoke were 0.26 as likely to smoke in the future compared to adolescents who provided the lowest estimates of risk. These effects are over three times as large as a smoking peer’s influence on a nonsmoking adolescents’ risk for smoking initiation, odds ratio [OR] = 1.18 (95% CI = 1.02–1.35).
Adolescent perceptions of risks of second-hand smoke are strongly associated with smoking initiation. Encouraging adolescents to express their objections to second-hand smoke, as well as encouraging parents to create smoke-free homes, may be powerful tobacco control strategies against adolescent smoking.
PMCID: PMC2814413  PMID: 19931835
Adolescent smoking; Second-hand smoke; Risk perception; Attitudes; Psychosocial risk factors; Decision making; Longitudinal study
14.  Smoking and high-risk mammographic parenchymal patterns: a case-control study 
Breast Cancer Research  1999;2(1):59-63.
Current smoking was strongly and inversely associated with high-risk patterns, after adjustment for concomitant risk factors. Relative to never smokers, current smokers were significantly less likely to have a high-risk pattern. Similar results were obtained when the analysis was confined to postmenopausal women. Past smoking was not related to the mammographic parenchymal patterns. The overall effect in postmenopausal women lost its significance when adjusted for other risk factors for P2/DY patterns that were found to be significant in the present study, although the results are still strongly suggestive. The present data indicate that adjustment for current smoking status is important when evaluating the relationship between mammographic parenchymal pattern and breast cancer risk. They also indicate that smoking is a prominent potential confounder when analyzing effects of other risk factors such as obesity-related variables. It appears that parenchymal patterns may act as an informative biomarker of the effect of cigarette smoking on breast cancer risk.
Overall, epidemiological studies [1,2,3,4] have reported no substantial association between cigarette smoking and the risk of breast cancer. Some studies [5,6,7] reported a significant increase of breast cancer risk among smokers. In recent studies that addressed the association between breast cancer and cigarette smoking, however, there was some suggestion of a decreased risk [8,9,10], especially among current smokers, ranging from approximately 10 to 30% [9,10]. Brunet et al [11] reported that smoking might reduce the risk of breast cancer by 44% in carriers of BRCA1 or BRCA2 gene mutations. Wolfe [12] described four different mammographic patterns created by variations in the relative amounts of fat, epithelial and connective tissue in the breast, designated N1, P1, P2 and DY. Women with either P2 or DY pattern are considered at greater risk for breast cancer than those with N1 or P1 pattern [12,13,14,15]. There are no published studies that assessed the relationship between smoking and mammographic parenchymal patterns.
To evaluate whether mammographic parenchymal patterns as classified by Wolfe, which have been positively associated with breast cancer risk, are affected by smoking. In this case-control study, nested within the European Prospective Investigation on Cancer in Norfolk (EPIC-Norfolk) cohort [16], the association between smoking habits and mammographic parenchymal patterns are examined. The full results will be published elsewhere.
Study subjects were members of the EPIC cohort in Norwich who also attended the prevalence screening round at the Norwich Breast Screening Centre between November 1989 and December 1997, and were free of breast cancer at that screening. Cases were defined as women with a P2/DY Wolfe's mammographic parenchymal pattern on the prevalence screen mammograms. A total of 203 women with P2/DY patterns were identified as cases and were individually matched by date of birth (within 1 year) and date of prevalence screening (within 3 months) with 203 women with N1/P1 patterns who served as control individuals.
Two views, the mediolateral and craniocaudal mammograms, of both breasts were independently reviewed by two of the authors (ES and RW) to determine the Wolfe mammographic parenchymal pattern.
Considerable information on health and lifestyle factors was available from the EPIC Health and Lifestyle Questionnaire [16]. In the present study we examined the subjects' personal history of benign breast diseases, menstrual and reproductive factors, oral contraception and hormone replacement therapy, smoking, and anthropometric information such as body mass index and waist:hip ratio.
Odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated by conditional logistic regression [17], and were adjusted for possible confounding factors.
The characteristics of the cases and controls are presented in Table 1. Cases were leaner than controls. A larger percentage of cases were nulliparous, premenopausal, current hormone replacement therapy users, had a personal history of benign breast diseases, and had had a hysterectomy. A larger proportion of controls had more than three births and were current smokers.
Table 2 shows the unadjusted and adjusted OR estimates for Wolfe's high-risk mammographic parenchymal patterns and smoking in the total study population and in postmenopausal women separately. Current smoking was strongly and inversely associated with high-risk patterns, after adjustment for concomitant risk factors. Relative to never smokers, current smokers were significantly less likely to have a high-risk pattern (OR 0.37, 95% CI 0.14-0.94). Similar results were obtained when the analysis was confined to postmenopausal women. Past smoking was not related to mammographic parenchymal patterns. The overall effect in postmenopausal women lost its significance when adjusted for other risk factors for P2/DY patterns that were found to be significant in the present study, although the results were still strongly suggestive. There was no interaction between cigarette smoking and body mass index.
In the present study we found a strong inverse relationship between current smoking and high-risk mammographic parenchymal patterns of breast tissue as classified by Wolfe [12]. These findings are not completely unprecedented; Greendale et al [18] found a reduced risk of breast density in association with smoking, although the magnitude of the reduction was unclear. The present findings suggest that this reduction is large.
Recent studies [9,10] have suggested that breast cancer risk may be reduced among current smokers. In a multicentre Italian case-control study, Braga et al [10] found that, relative to nonsmokers, current smokers had a reduced risk of breast cancer (OR 0.84, 95% CI 0.7-1.0). These findings were recently supported by Gammon et al [9], who reported that breast cancer risk in younger women (younger than 45 years) may be reduced among current smokers who began smoking at an early age (OR 0.59, 95% CI 0.41-0.85 for age 15 years or younger) and among long-term smokers (OR 0.70, 95% CI 0.52-0.94 for those who had smoked for 21 years or more).
The possible protective effect of smoking might be due to its anti-oestrogenic effect [1,2,19]. Recently there has been renewed interest in the potential effect of smoking on breast cancer risk, and whether individuals may respond differently on the basis of differences in metabolism of bioproducts of smoking [20,21]. Different relationships between smoking and breast cancer risk have been suggested that are dependent on the rapid or slow status of acetylators of aromatic amines [20,21]. More recent studies [22,23], however, do not support these findings.
The present study design minimized the opportunity for bias to influence the findings. Because subjects were unaware of their own case-control status, the possibility of recall bias in reporting smoking status was minimized. Systematic error in the assessment of mammograms was avoided because reading was done without knowledge of the risk factor data. Furthermore, the associations observed are unlikely to be explained by the confounding effect of other known breast cancer risk factors, because we adjusted for these in the analysis. We did not have information on passive smoking status, however, which has recently been reported to be a possible confounder [5,6,21,24].
The present data indicate that adjustment for current smoking status is important when evaluating the relationship between mammographic parenchymal pattern and breast cancer risk. They also indicate smoking as a prominent potential confounder when analyzing effects of other risk factors such as obesity-related variables. It seems that parenchymal patterns may act as an informative biomarker of the effect of cigarette smoking on breast cancer risk.
PMCID: PMC13911  PMID: 11056684
mammography; screening; smoking; Wolfe's parenchymal patterns
15.  Respiratory symptoms in relation to residential coal burning and environmental tobacco smoke among early adolescents in Wuhan, China: a cross-sectional study 
Environmental Health  2004;3:14.
Cigarette smoking and coal burning are the primary sources of indoor air pollution in Chinese households. However, effects of these exposures on Chinese children's respiratory health are not well characterized.
Seventh grade students (N = 5051) from 22 randomly selected schools in the greater metropolitan area of Wuhan, China, completed an in-class self-administered questionnaire on their respiratory health and home environment.
Coal burning for cooking and/or heating increased odds of wheezing with colds [odds ratio (OR) = 1.57, 95% confidence interval (CI): 1.07–2.29] and without colds (OR = 1.44, 95% CI: 1.05–1.97). For smoking in the home, the strongest associations were seen for cough (OR = 1.74, 95% CI: 1.17–2.60) and phlegm production (OR = 2.25, 95% CI: 1.36–3.72) without colds among children who lived with two or more smokers.
Chinese children living with smokers or in coal-burning homes are at increased risk for respiratory impairment. While economic development in China may decrease coal burning by providing cleaner fuels for household energy use, the increasing prevalence of cigarette smoking is a growing public health concern due to its effects on children. Adverse effects of tobacco smoke exposure were seen despite the low rates of maternal smoking (3.6%) in this population.
PMCID: PMC543575  PMID: 15585063
16.  Effect of seeing tobacco use in films on trying smoking among adolescents: cross sectional study 
BMJ : British Medical Journal  2001;323(7326):1394.
To test the hypothesis that greater exposure to smoking in films is associated with trying smoking among adolescents.
Cross sectional survey of 4919 schoolchildren aged 9-15 years, and assessment of occurrence of smoking in 601 films.
Randomly selected middle schools in Vermont and New Hampshire, USA.
Main outcome measure
Number of schoolchildren who had ever tried smoking a cigarette.
The films contained a median of 5 (interquartile range 1-12) occurrences of smoking. The typical adolescent had seen 17 of 50 films listed. Exposure to smoking in films varied widely: median 91 (49-152) occurrences. The prevalence of ever trying smoking increased with higher categories of exposure: 4.9% among students who saw 0-50 occurrences of smoking, 13.7% for 51-100 occurrences, 22.1% for 101-150, and 31.3% for >150. The association remained significant after adjustment for age; sex; school performance; school; parents' education; smoking by friend, sibling, or parent; and receptivity to tobacco promotions. The adjusted odds ratios of ever trying smoking for students in the higher categories of exposure, compared with students exposed to 0-50 occurrences of smoking in films, were 1.7 (95% confidence interval 1.2 to 2.4), 2.4 (1.7 to 3.4), and 2.7 (2.0 to 3.8). These odds ratios were not substantially affected by adjustment for parenting style or for personality traits of the adolescent.
In this sample of adolescents there was a strong, direct, and independent association between seeing tobacco use in films and trying cigarettes, a finding that supports the hypothesis that smoking in films has a role in the initiation of smoking in adolescents.
What is already known on this topicSmoking is often depicted in films, and watching films is a favourite activity of adolescentsAdolescents whose favourite actors smoke in films are more likely to have tried smokingWhat this study addsAdolescents' exposure to smoking in films varies widelyAdolescents with higher exposure are significantly more likely to have tried smoking, even when other factors linked with adolescent smoking have been taken into accountThis study supports the hypothesis that depictions of smoking in films influence adolescents to smoke
PMCID: PMC60983  PMID: 11744562
17.  Validation of a self-report questionnaire version of the Child Activity Limitations Interview (CALI): The CALI-21 
Pain  2008;139(3):644-652.
The Child Activity Limitations Interview (CALI) is a measure designed to assess functional impairment due to chronic pain in school-age children. In this study, we present a self-report questionnaire version of the CALI (the CALI-21) that extends the original interview measure. The purpose of the current study was to provide internal consistency, cross-informant reliability and construct validity of the CALI-21 on a clinical sample of children and adolescents with chronic pain conditions. One hundred fifty-five children and adolescents (65 males, 90 females; ages 8–18 years, M = 14.31, SD =2.45) with chronic pain completed questionnaires as part of their clinic intake procedures at their consultation visit in a pediatric pain management clinic. An exploratory factor analysis was conducted to measure latent constructs within the broader domain of functional impairment. Results of the exploratory factor analysis yielded two factors representing limitation in Active and Routine activities on both parent and child report. Parent and child total CALI scores correlated with measures of pain intensity, however, different patterns of correlations emerged between age, pain intensity, depressive symptoms, and the Active and Routine factors. The CALI-21 showed good internal consistency, high cross-informant reliability, and demonstrated construct validity. The CALI-21 provides increased flexibility via the questionnaire format in the assessment of pain-related activity limitations in children. Factor analysis extends information about specific types of activity limitations experienced by children.
PMCID: PMC3166250  PMID: 18692316
18.  Predictors of smoking among Swedish adolescents 
BMC Public Health  2014;14(1):1296.
Smoking most often starts in adolescence, implying that understanding of predicting factors for smoking initiation during this time period is essential for successful smoking prevention. The aim of this study was to examine predicting factors in early adolescence for smoking in late adolescence.
Longitudinal cohort study, involving 649 Swedish adolescents from lower secondary school (12–13 years old) to upper secondary school (17–18 years old). Tobacco habits, behavioural, intra- and interpersonal factors and socio-demographic variables were assessed through questionnaires. Descriptive statistics, univariable and multivariable logistic regression were used to identify predicting factors.
Smoking prevalence increased from 3.3% among 12–13 year olds to 25.1% among 17–18 year olds. Possible predictors of smoking were: female sex, lower parental education, poorer family mood, poorer self-rated health, poorer self-esteem, less negative attitude towards smoking, binge drinking, snus use and smoking. In a multivariable logistic regression analysis, female sex (OR 1.64, CI 1.08-2.49), medium and low self-esteem (medium: OR 1.57, CI 1.03-2.38, low: 2.79, CI 1.46-5.33), less negative attitude towards smoking (OR 2.81, CI 1.70-4.66) and ever using snus (OR 3.43, CI 1.78-6.62) remained significant independent predicting factors.
The study stresses the importance of strengthening adolescents’ self-esteem, promoting anti-smoking attitudes in early adolescence, as well as avoidance of early initiation of snus. Such measures should be joint efforts involving parents, schools, youth associations, and legislating authorities.
PMCID: PMC4300986  PMID: 25518992
Smoking; Adolescence; Smokeless tobacco; Snus; Self-esteem; Attitudes; Longitudinal study
19.  Exposure to Smoking in Popular Contemporary Movies and Youth Smoking in Germany 
Studies have linked exposure to movie smoking and smoking initiation among U.S. adolescents, but there has been only one published study of adolescents outside the U.S.
Cross sectional survey of 5586 schoolchildren aged 10–17 with a mean of 12.8 (SD=1.2) years from randomly selected secondary schools in Schleswig-Holstein, Germany, in October/November 2005. In August 2006, using previously validated methods, exposure to movie smoking was estimated from 398 internationally distributed films (98% produced and distributed by U.S. studios) released in Germany, and examined its relation with ever and current (30 day) smoking.
Overall, 40.7% of the sample had tried smoking, and 12.3% were current smokers. The sample quartile (Q) of movie smoking exposure was significantly associated with the prevalence of smoking initiation: 0.17 of adolescents in Q1 had tried smoking; 0.35 in Q2; 0.47 in Q3; and 0.64 in Q4. Movie smoking exposure was significantly associated with the prevalence of current smoking: 0.03 for adolescents in Q1; 0.08 in Q2; 0.14 in Q3; and 0.25 in Q4. After controlling for sociodemographics, parent/friend/sibling smoking, school performance, personality characteristics, TV consumption, receptivity to tobacco marketing and parenting style, the adjusted odds ratios for having tried smoking were 1.7 (95% confidence interval [CI]: 1.4, 2.1) for Q2, 1.8 (95% CI: 1.5, 2.3) for Q3, and 2.2 (95% CI: 1.8, 2.8) for Q4 compared with adolescents in Q1. The adjusted odds ratios for current smoking were 1.4 (95% CI: 0.9, 2.2) for Q2, 1.7 (95% CI: 1.1, 2.6) for Q3, and 2.0 (95% CI: 1.3, 3.1) for Q4 compared with adolescents in Q1.
Smoking in internationally distributed movies is associated with ever and current smoking among German adolescents. This suggests the need for prospective studies of this association in countries other than the U.S. and research into the potential impact of countrywide policies that would limit exposure of young adolescents to movie smoking.
PMCID: PMC1963468  PMID: 17533061
20.  The Role of Cognitive Attributions for Smoking in Subsequent Smoking Progression and Regression among Adolescents in China 
Addictive behaviors  2012;38(1):1493-1498.
Previous studies have documented that cognitive attributions are correlated with adolescent smoking. The present study further explored whether cognitive attributions for smoking influenced adolescents’ future smoking behaviors, especially transitions to more advanced stages of smoking.
Participants were 12,382 middle and high school students (48.5% males and 51.5% females) in seven large cities in China. They completed two waves of surveys one year apart. Cognitive attributions for smoking and three smoking behavior outcomes (lifetime smoking, past 30-day smoking, and daily smoking) were assessed. Changes in smoking, including progression from lower stages to higher stages and regression from higher stages to lower stages, over a one-year period, were defined longitudinally. Polychotomous logistic regression was used to examine associations between cognitive attributions for smoking and changes in smoking status over one year, adjusting for demographic characteristics and other plausible confounders.
Seven out of eight cognitive attributions for smoking were associated with subsequent smoking behaviors (p<0.05). Curiosity, autonomy, social image, social belonging, and coping influenced earlier stages of smoking, whereas mental enhancement and engagement influenced later stages of smoking. Curiosity, autonomy, social image, and mental enhancement preceded smoking progression; social belonging prevented smoking regression; and coping and engagement both preceded smoking progression and prevented smoking regression.
This study demonstrates that different cognitive attributions influence smoking at different stages in different ways. These findings could inform smoking prevention and cessation programs targeting Chinese adolescents.
PMCID: PMC3493682  PMID: 23017586
Attributions; Smoking; Attribution Theory; Adolescents; China
21.  Clustering of substance use and sexual risk behaviour in adolescence: analysis of two cohort studies 
BMJ Open  2012;2(1):e000661.
The authors aimed to examine whether changes in health risk behaviour rates alter the relationships between behaviours during adolescence, by comparing clustering of risk behaviours at different time points.
Comparison of two cohort studies, the Twenty-07 Study (‘earlier cohort’, surveyed in 1987 and 1990) and the 11-16/16+ Study (‘later cohort’, surveyed 1999 and 2003).
Central Clydeside Conurbation around Glasgow City.
Young people who participated in the Twenty-07 and 11-16/16+ studies at ages 15 and 18–19.
Primary and secondary outcomes measures
The authors analysed data on risk behaviours in both early adolescence (started smoking prior to age 14, monthly drinking and ever used illicit drugs at age 15 and sexual intercourse prior to age 16) and late adolescence (age 18–19, current smoking, excessive drinking, ever used illicit drugs and multiple sexual partners) by gender and social class.
Drinking, illicit drug use and risky sexual behaviour (but not smoking) increased between the earlier and later cohort, especially among girls. The authors found strong associations between substance use and sexual risk behaviour during early and late adolescence, with few differences between cohorts, or by gender or social class. Adjusted ORs for associations between each substance and sexual risk behaviour were around 2.00. The only significant between-cohort difference was a stronger association between female early adolescent smoking and early sexual initiation in the later cohort. Also, relationships between illicit drug use and both early sexual initiation and multiple sexual partners in late adolescence were significantly stronger among girls than boys in the later cohort.
Despite changes in rates, relationships between adolescent risk behaviours remain strong, irrespective of gender and social class. This indicates a need for improved risk behaviour prevention in young people, perhaps through a holistic approach, that addresses the broad shared determinants of various risk behaviours.
Article summary
Article focus
Previous studies have reported clustering of risk behaviours during adolescence.
Prior studies have not examined whether changes in risk behaviour rates affects relationships between these risk behaviours.
We examined clustering in early and later adolescent risk behaviours to determine if clustering differed at two different time points, by gender and by socioeconomic status, the latter of which has also tended not to be addressed in previous studies.
Key messages
Despite changes in health risk behaviour rates, relationships between adolescent risk behaviours remain strong.
Relationships generally did not vary by gender or social class.
There is a need for improved risk behaviour prevention in young people, perhaps through a holistic approach that addresses the broad shared determinants of various risk behaviours.
Strengths and limitations of this study
We compared cohorts of young people from the same geographic area and life stage, surveyed using (near) identical questions, 13 years apart. To our knowledge, this is the first study to examine time trends in associations between substance use and sexual behaviour.
We examined these associations in both early and late adolescence and by gender and social class, the latter of which has not been previously investigated.
Although we accounted for loss to follow-up in the 1999/2003 study via weighted analyses, we may not have fully compensated for differential loss to follow-up of adolescents with more ‘risky’ patterns of behaviour.
Questions on alcohol intake included a more detailed drinking grid in the 1999/2003 study, which possibly encouraging increased reporting in this later cohort, while use of interviewer-administered questionnaires may have led to under-reporting of behaviours.
PMCID: PMC3330258  PMID: 22318665
22.  Cigarette smoking among school-going adolescents in Lithuania: Results from the 2005 Global Youth Tobacco Survey 
BMC Research Notes  2010;3:130.
The majority of people who suffer morbidity due to smoking may have initiated smoking during adolescent period. The aim of this study is to determine the prevalence and associated factors for cigarette smoking among school-going adolescents in Lithuania.
Data from the Global Youth Tobacco Survey (GYTS) 2005 were used to conduct this study. Data were analyzed using SUDAAN software 9.03. Comparisons for categorical variables were done using the Pearson's Chi-square test. The cut of point for statistical significance was set at 5% level. Logistic regression analyses were conducted to determine factors associated with the outcome. Unadjusted odds ratios (OR) and adjusted odds ratios (AOR) together with their 95% confidence intervals (CI) are reported.
Of the 1822 respondents, 35.8% males and 27.1% females reported being current cigarette smokers (p < 0.001). Having friends who smoke cigarettes was associated with smoking after controlling for age, gender, parental smoking status, and perception of risks of smoking (AOR = 3.76; 95% CI [2.33, 6.90] for some friends using tobacco; and AOR = 17.18; 95% CI [10.46, 28.21] for most or all friends using tobacco). Male gender and having one or both parents who smoke cigarettes were associated with smoking (AOR = 1.31; 95% CI [1.03, 1.66]) and AOR = 1.76; 95% CI [1.37, 2.27]) respectively).
There is a high prevalence of cigarette smoking among Lithuanian adolescents. Male adolescents and adolescents who have friends or parents who smoke should be the main target for tobacco control in Lithuania.
PMCID: PMC2873352  PMID: 20459649
23.  Polygenic risk accelerates the developmental progression to heavy, persistent smoking and nicotine dependence: Evidence from a 4-Decade Longitudinal Study 
JAMA psychiatry (Chicago, Ill.)  2013;70(5):534-542.
To test how genomic loci identified in genome-wide association studies (GWAS) influence the developmental progression of smoking behavior.
A 38-year prospective longitudinal study of a representative birth-cohort.
The Dunedin Multidisciplinary Health and Development Study, New Zealand.
N=1037 male and female study members.
We assessed genetic risk with a multi-locus genetic risk score (GRS). The GRS was composed of single-nucleotide polymorphisms identified in three meta-analyses of GWAS of smoking quantity phenotypes.
Smoking initiation, conversion to daily smoking, progression to heavy smoking, nicotine dependence (Fagerstrom Test of Nicotine Dependence), and cessation difficulties were evaluated at eight assessments spanning ages 11-38 years.
Genetic risk score was unrelated to smoking initiation. However, individuals at higher genetic risk were more likely to convert to daily smoking as teenagers, progressed more rapidly from smoking initiation to heavy smoking, persisted longer in smoking heavily, developed nicotine dependence more frequently, were more reliant on smoking to cope with stress, and were more likely to fail in their cessation attempts. Further analysis revealed that two adolescent developmental phenotypes—early conversion to daily smoking and rapid progression to heavy smoking--mediated associations between the genetic risk score and mature phenotypes of persistent heavy smoking, nicotine dependence, and cessation failure. The genetic risk score predicted smoking risk over and above family history.
Initiatives that disrupt the developmental progression of smoking behavior among adolescents may mitigate genetic risks for developing adult smoking problems. Future genetic research may maximize discovery potential by focusing on smoking behavior soon after smoking initiation and by studying young smokers.
PMCID: PMC3644004  PMID: 23536134
24.  Multilevel Predictors of Smoking Initiation among Adolescents: Findings from the Minnesota Adolescent Community Cohort (MACC) Study 
Preventive Medicine  2012;54(3-4):242-246.
To understand how factors at multiple levels of influence impact adolescent smoking initiation.
Data from the Minnesota Adolescent Community Cohort, a population-based cohort, were analyzed. Adolescents were recruited from randomly selected geopolitical units (GPUs) in Minnesota at ages 12 to 13 (n=1,953), and were surveyed every six months (2000–2006) until 18. The association between baseline social factors and smoking initiation was analyzed using logistic regression. Linear regression was used to analyze predictors and age of initiation among smokers (n=603).
Higher proportion of 15–16 year-olds who smoke at the area-level (GPU) was associated with younger initiation (15.47 vs 15.87, p<.05). Higher proportion of the population employed and higher median household income were associated with older initiation (15.90 vs. 15.56 p<.05). Parent education, living with parents or siblings who smoke, living in homes that allow smoking, and having friends who smoke at baseline were associated with smoking initiation or younger initiation (p<.05). Participants whose parents had less than a high school education were 1.6 times more likely than those with college educated parents to have smoked more than a whole cigarette (CI=1.06, 2.26).
Factors at multiple levels of influence affect adolescent smoking initiation. Smoking by older age peers and lower SES predicts earlier smoking.
PMCID: PMC3319284  PMID: 22245269
25.  Child Abuse and Smoking Among Young Women: The Importance of Severity, Accumulation, and Timing 
We examined the association between severity, accumulation, and timing of abuse in childhood and adolescence and smoking status among young women.
Retrospective self-reported childhood abuse was ascertained with the modified Conflict Tactics Scale from 91,286 Nurses Health Study II participants in 2001 (68,505 returned; 75.0% response rate). Childhood abuse was categorized by severity (mile/moderate/severe), type (physical/sexual), and timing (childhood/adolescence). Smoking status during adolescence was reported at baseline (1989). Logistic regression was used to predict smoking initiation by age 14 and smoking status between the ages of 15 and 19.
A graded association between severity of abuse and early initiation of smoking (by age 14 years) was demonstrated (odds ratio [OR] = 1.9, 95% confidence interval [CI] = 1.7–2.1 for severe physical violence). Young women with both physical and sexual abuse were two times more likely to start smoking by age 14 than were those reporting no abuse (OR = 2.0, 95% CI = 1.8–2.3). Although abuse during childhood increased risk for adolescent smoking (OR = 1.7, 95% CI = 1.8–2.1) for those with childhood physical and sexual abuse, inclusion of adolescent physical and sexual abuse (OR = 2.2, 95% CI 2.1–2.4) diminished the impact of childhood abuse (OR = 1.1, 95% CI 1.1–1.2). The degree of familial emotional support was protective against smoking, and reduced the impact of abuse by 40% among those with high emotional support versus those without (p < .0001).
A strong and graded association was observed between both severity and accumulation of abuse and the risk of early initiation of smoking among girls. Smoking status during late adolescence was more strongly associated with adolescent abuse than childhood abuse. Early smoking onset is associated with both heightened risk for disease in adolescence but also increased morbidity and mortality in adulthood. Identifying and intervening in potentially modifiable risk factors for smoking onset in young women, such as early-life physical and sexual abuse, and building familial strengths, such as emotional support, may have significant public health implications.
PMCID: PMC3932335  PMID: 18565438
Smoking initiation; Childhood abuse; Young women

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