The implications of simultaneous smoking initiation for inferences about the genetics of smoking behavior from twin data

We examined early social influences across stages of smoking within the context of a twin study using an environmental exposure specific to smoking: whether twins started smoking at the same time (simultaneous smoking initiation: SSI). We expected that SSI would be a good index of shared social influences on smoking initiation. Rates of SSI were indeed significantly higher in MZ twins and in twins who shared peers and classes, as well as in male twins. With the exception of regular smoking in females, we found no significant difference in estimates of genetic and environmental parameters between SSI and non-SSI pairs for any of the smoking measures that we examined (DSM-IV and Fagerstrom HSI measures of nicotine dependence; DSM-IV nicotine withdrawal; heavy smoking; and in males, regular smoking). For regular smoking in females, allowing for additional shared environmental influences associated with SSI only modestly reduced our estimates of additive genetic variance (56% vs. 68%). These results indicate the important social influences that may occur for smoking initiation do not appear to seriously bias estimates of genetic effects on later stages of smoking.

Chronic smoking and alcoholism change expression of selective genes in the human prefrontal cortex

Background: Alcoholism is commonly associated with chronic smoking. A number of gene expression profiles of regions within the human mesocorticolimbic system have identified potential alcohol-sensitive genes; however, the influence of smoking on these changes was not taken into account. This study addressed the impact of alcohol and smoking on the expression of 4 genes, previously identified as alcoholism-sensitive. in the human prefrontal cortex (PFC). Methods: mRNA expression of apolipoprotein D, tissue inhibitor of the metalloproteinase 3, high-affinity glial glutamate transporter and midkine, was measured in the PFC of alcoholic Subjects and controls with and without smoking comorbidity using real-time polymerase chain reaction. Results: The results show that alcohol affects transcription of some of these genes. Additionally, smoking has a marked influence on gene expression. Conclusion: This study emphasizes the need for careful case selection in future gene expression studies to delineate the adaptive molecular process associated with smoking and alcohol.

Determinants of stages of smoking uptake among secondary school students

With the uptake of cigarette smoking hypothesised to occur through a series of contemplation and action stages, we sought to investigate what factors are associated with the contemplation of smoking among secondary school students in Queensland, Australia. A series of four cross-sectional surveys were conducted among secondary schools in Queensland in 1993, 1996, 1999 and 2002. Respondents (n = 9993) were asked about the stages of smoking. Nearly half (43%) of secondary school students reported some contemplation of smoking. Increased levels of smoking contemplation were observed among females, earlier survey years, Junior level students, students with average or below average scholastic ability, those prepared to go out with a smoker, those with recent alcohol experience, those who bad influenced other students to smoke or had not discouraged other students smoking. The results of this study provide further information about the factors relevant to stages of smoking uptake among secondary school students and the influence that students may have on their peers. (c) 2005 Elsevier Ltd. All rights reserved.

From partying to parenthood: young women's perceptions of cigarette smoking across life transitions

This study explored influences on adoption, maintenance and cessation of smoking among young women as they experienced life transitions: leaving home, gaining employment or attending college/university, marriage and parenthood. Standardized, open-ended telephone interviews were conducted with 80 women (including never smokers, continuing smokers, recent adopters and quitters) aged 24-29 years, recruited from participants in the Australian Longitudinal Study on Women's Health. The social context of smoking (socializing with other smokers, drinking alcohol and going to pubs and clubs) was perceived to be a predominant influence on smoking from the time young women left home until they settled into a committed relationship or started their own family. Stress was identified as an important factor as they experienced lifestyle changes. An increased sensitivity to the negative aspects of smoking after turning 21 was reported, and around the mid-20s the women became concerned about the addictive nature of cigarettes. Motherhood was seen to carry increased responsibilities to protect children from passive smoking and there was a perceived importance of positive role modelling to protect children from becoming smokers themselves. This study highlights the need for public health campaigns to address the social role that smoking plays in young women's lives, and the perceived use of cigarettes for stress relief. Life changes such as settling down with a partner and the contemplation of motherhood provide opportunities for targeted interventions to promote quitting.

Gender differentials in the evolution of cigarette smoking habits in a general European adult population from 1993-2003

Background: Describe the recent evolution of cigarette smoking habits by gender in Geneva, where incidence rates of lung cancer have been declining in men but increasing in women. Methods: Continuous cross-sectional surveillance of the general adult ( 35 - 74 yrs) population of Geneva, Switzerland for 11 years ( 1993 - 2003) using a locally-validated smoking questionnaire, yielding a representative random sample of 12,271 individuals ( 6,164 men, 6,107 women). Results: In both genders, prevalence of current cigarette smoking was stable over the 11-year period, at about one third of men and one quarter of women, even though smoking began at an earlier age in more recent years. Older men were more likely to be former smokers than older women. Younger men, but not women, tended to quit smoking at an earlier age. Conclusion: This continuous ( 1993 - 2003) risk factor surveillance system, unique in Europe, shows stable prevalence of smoking in both genders. However, sharp contrasts in age-specific prevalence of never and former smoking and of ages at smoking initiation indicate that smoking continues a long-term decline in men but has still not reached its peak in women.

In utero and postnatal maternal smoking and asthma in adolescence

Background: Asthma in early childhood has been associated with maternal smoking during pregnancy and parental smoking soon after birth. However, less is known about these exposures and the development of asthma symptoms in adolescence. Methods: Data were taken from the Mater University Study, of Pregnancy, a large birth cohort study of mothers and children enrolled in Brisbane, Australia, beginning in 1981. Smoking was assessed at 2 stages during pregnancy and at the 6-month and 5-year follow-up visits. Asthma was assessed from maternal reports that were provided when the child was age 14 years. We conducted multivariable multinomial logistic regression analyses to assess the effect of maternal smoking on asthma symptoms. Results: There was a strong sex interaction such that girls whose mothers had smoked heavily (20 or more cigarettes per day) in pregnancy and at the 6-month follow up had increased odds of experiencing asthma symptoms at age 14 (odds ratio = 1.96; 95% confidence interval = 1.25-3.08). The contribution of heavy smoking during pregnancy appeared to be stronger than heavy smoking after the birth. No similar associations were seen for boys. Conclusion: Female adolescents whose mothers smoked heavily during the fetal period and the early months of life have increased risk of asthma symptoms in adolescence. In utero exposure to heavy smoking was found to have a stronger effect than postnatal environmental tobacco exposure.

Smoking and schizophrenia: is symptom profile related to smoking and which antipsychotic medication is of benefit in reducing cigarette use?

Smoking rate is disproportionately high among patients with schizophrenia, resulting in significant morbidity and mortality. However, cigarette smoking has been reported to have beneficial effects on negative symptoms, extrapyramidal symptoms, cognitive functioning and mood symptoms. Therefore, smoking cessation may worsen disability in schizophrenia. The association between smoking and these key clinical parameters was examined. Additionally, severity of smoking across four different antipsychotic treatment groups was explored. One hundred and forty-six patients with schizophrenia were assessed for smoking using expired carbon monoxide and smoking history. They were administered the Positive and Negative Symptom Scale, The Extrapyramidal Symptom Rating Scale, the Barnes Akathisia Rating Scale, Reitans Trail-making Test (A and B) and General Health Questionnaire-28. There was no difference in the chlorpromazine equivalent dose of any of the medications studied. Atypical agents were associated with significantly lower levels of smoking when compared with typical medications. There was no difference in smoking severity between the individual atypical medications examined. Similarly, there were no significant differences between smoking and non-smoking groups with regard to Positive and Negative Symptom Scale, Extrapyramidal Symptom Rating Scale, Trail-making Test and General Health Questionnaire-28. However, there was a significant difference between these groups with the smoking group demonstrating less akathisia. Smoking is not associated with positive, negative cognitive and mood symptoms in schizophrenia. Smoking is associated with lower levels of antipsychotic induced akathisia. Clinicians should not be discouraged from helping patients stop smoking for fear of worsening symptoms. However, akathisia may emerge upon cessation of smoking. Switching patients from typical to atypical antipsychotics may assist patients with schizophrenia to give up smoking.

Smoking status of Australian general practice patients and their attempts to quit

This paper seeks to report on smoking rates, quit attempt methods and success rates among adult patients attending Australian general practice. A cluster cross-sectional survey was used to survey adult patients (18+), who attended Australian GPs in during 2002 and 2003. Over a quarter of patients (27.3%; 95% CI: 26.0-28.7) were former smokers and one in five (21.5%; 95% CI: 20.1-22.9) were current smokers. Ninety-two percent of former and 80% of current smokers used only one method in their last quit attempt with cold turkey the most common method used by both former (88%) and current (62%) smokers. Overall, success rates varied from 77% for cold turkey to 23% for bupropion. Success rates were re-analysed to consider quit attempts post-bupropion listing, with success rate for cold turkey reduced to 40% while bupropion remained reasonably constant at 21%. By tailoring smoking cessation interventions to a smokers' preparedness to quit, scope exists to increase the pool of smokers offered strategies that are more effective in achieving abstinence and avoiding relapse rather than relying on less effective self-quitting behaviours such as cold turkey. (c) 2005 Elsevier Ltd. All rights reserved.

Social inequalities in male mortality, and in male mortality from smoking: indirect estimation from national death rates in England and Wales, Poland, and North America

Background There are substantial social inequalities in adult male mortality in many countries. Smoking is often more prevalent among men of lower social class, education, or income. The contribution of smoking to these social inequalities in mortality remains uncertain. Methods The contribution of smoking to adult mortality in a population can be estimated indirectly from disease-specific death rates in that population (using absolute lung cancer rates to indicate proportions due to smoking of mortality from certain other diseases). We applied these methods to 1996 death rates at ages 35-69 years in men in three different social strata in four countries, based on a total of 0.6 million deaths. The highest and lowest social strata were based on social class (professional vs unskilled manual) in England and Wales, neighbourhood income (top vs bottom quintile) in urban Canada, and completed years of education (more than vs less than 12 years) in the USA and Poland. Results In each country, there was about a two-fold difference between the highest and the lowest social strata in overall risks of dying among men aged 35-69 years (England and Wales 21% vs 43%, USA 20% vs 37%, Canada 21% vs 34%, Poland 26% vs 50%: four-country mean 22% vs 41%, four-country mean absolute difference 19%). More than half of this difference in mortality between the top and bottom social strata involved differences in risks of being killed at age 35-69 years by smoking (England and Wales 4% vs 19%, USA 4% vs 15%, Canada 6% vs 13%, Poland 5% vs 22%: four-country mean 5% vs 17%, four-country mean absolute difference 12%). Smoking-attributed mortality accounted for nearly half of total male mortality in the lowest social stratum of each country. Conclusion In these populations, most, but not all, of the substantial social inequalities in adult male mortality during the 1990s were due to the effects of smoking. Widespread cessation of smoking could eventually halve the absolute differences between these social strata in the risk of premature death.

Does timing and sequencing of transitions to adulthood make a difference? Stress, smoking, and physical activity among young Australian women

The major changes of the transition to adulthood are argued to be stressful, and health-related behaviors such as smoking and physical activity may be adopted, consolidated, or abandoned at this time. On the other hand, research has suggested that the normative transitions of emerging adulthood, although involving considerable change, may be associated with low stress because they are perceived as both positive and normal at this life stage. This article examines relations between the timing and sequencing of life transitions and stress and health-related behaviors, focusing on the transition to young adulthood among Australian women. A total of 853 women aged 22 to 27 provided information about the timing and sequencing of 6 life transitions: moving out of home, stopping full-time education, starting full-time work, having the first live-in relationship, marriage, and motherhood-and stress, smoking, and physical activity. Most had moved out of home, stopped full-time education, and started full-time work, but only 14% had undertaken all 6 transitions. Overall, 70% of participants had made transitions in order Overall, the findings suggest that the relations between timing and sequencing of transitions, and indicators of health, are moderate for smoking, but small for stress and for physical activity. These effects remained after controlling for socioeconomic status of the participants' families of origin. Matching current social norms for the timing and sequencing of life changes may be of less importance for women's well-being than is commonly believed. Although the significant relations between early or out of order transitions and smoking are of concern, the smaller relations with stress and with sedentariness suggest that such transitions may have limited negative consequences, and support the view that individuals are active in choosing the life path that is appropriate for them and their circumstances.

Genetic and Cultural Transmission of Smoking Initiation: An Extended Twin Kinship Model

Background Considerable evidence from twin and adoption studies indicates that genetic and shared environmental factors play a significant role in the initiation of smoking behavior. Although twin and adoption designs are powerful to detect genetic and environmental influences, they do not provide information on the processes of assortative mating and parent–offspring transmission and their contribution to the variability explained by genetic and/or environmental factors. Methods We examined the role of genetic and environmental factors for smoking initiation using an extended kinship design. This design allows the simultaneous testing of additive and non-additive genetic, shared and individual-specific environmental factors, as well as sex differences in the expression of genes and environment in the presence of assortative mating and combined genetic and cultural transmission. A dichotomous lifetime smoking measure was obtained from twins and relatives in the Virginia 30,000 sample. Results Results demonstrate that both genetic and environmental factors play a significant role in the liability to smoking initiation. Major influences on individual differences appeared to be additive genetic and unique environmental effects, with smaller contributions from assortative mating, shared sibling environment, twin environment, cultural transmission and resulting genotype–environment covariance. The finding of negative cultural transmission without dominance led us to investigate more closely two possible mechanisms for the lower parent–offspring correlations compared to the sibling and DZ twin correlations in subsets of the data: (i) age × gene interaction, and (ii) social homogamy. Neither mechanism provided a significantly better explanation of the data, although age regression was significant. Conclusions This study showed significant heritability, partly due to assortment, and significant effects of primarily non-parental shared environment on smoking initiation.

'Occasional' and 'social' smokers: Potential target groups for smoking cessation campaigns?

Objective: To describe the characteristics [of self-described 'occasional' and 'social' Australian smokers. Design: Analysis of a national cross-sectional survey of smoking patterns, conducted in Australia in 2004. Setting and participants: Australian adults in 2004 who responded to a survey question about self-described smoking status. Main outcome measures: Demographic characteristics, patterns of alcohol and tobacco use, smoking cessation attempts in the past year, and interest in cessation. Results: Smokers who described themselves as 'occasional' and 'social' smokers comprised 29% of all smokers. A significant proportion of occasional and social smokers had been daily smokers, but the majority either believed that they had 'already quit' or had no intention of quitting smoking. Conclusions: Self-ascribed occasional and social smokers potentially represent an important target group for cessation. These types of smokers may be more resistant to public health messages regarding cessation because they do not view their smoking behaviour as presenting a high risk.

The fraction of ischaemic heart disease and stroke attributable to smoking in the WHO Pacific and South-East Asian regions

Background: Tobacco will soon be the biggest cause of death worldwide, with the greatest burden being borne by low and middle-income countries where 8/10 smokers now live. Objective: This study aimed to quantify the direct burden of smoking for cardiovascular diseases (CVD) by calculating the population attributable fractions (PAF) for fatal ischaemic heart disease (IHD) and stroke (haemorrhagic and ischaemic) for all 38 countries in the World Health Organization Western Pacific and South East Asian regions. Design and subjects: Sex-specific prevalence of smoking was obtained from existing data. Estimates of the hazard ratio (HR) for IHD and stroke with smoking as an independent risk factor were obtained from the,600 000 adult subjects in the Asia Pacific Cohort Studies Collaboration (APCSC). HR estimates and prevalence were then used to calculate sex-specific PAF for IHD and stroke by country. Results: The prevalence of smoking in the 33 countries, for which relevant data could be obtained, ranged from 28-82% in males and from 1-65% in females. The fraction of IHD attributable to smoking ranged from 13-33% in males and from < 1-28% in females. The percentage of haemorrhagic stroke attributable to smoking ranged from 4-12% in males and from < 1-9% in females. Corresponding figures for ischaemic stroke were 11-27% in males and < 1-22% in females. Conclusions: Up to 30% of some cardiovascular fatalities can be attributed to smoking. This is likely an underestimate of the current burden of smoking on CVD, given that the smoking epidemic has developed further since many of the studies were conducted.