The genetic basis for smoking behavior: a systematic review and meta-analysis.

Considerable evidence indicates that smoking behavior is under a degree of genetic influence. We conducted a systematic review of candidate gene studies of smoking behavior and, where sufficient studies existed, combined reported data using meta-analytic techniques. A total of 41 studies were identified by the search strategy, of which 28 contributed to the meta-analysis. The meta-analysis included data on the DRD2, DAT, 5HTT, and CYP2A6 genes and smoking behavior. Categorical data were extracted on smoking status (never-smoker, ex-smoker, current smoker). Continuous data were extracted on number of cigarettes smoked per day. Evidence indicated effects of the DRD2 Taq1A polymorphism and smoking initiation, the 5HTT LPR and CYP2A6 reduced-activity polymorphisms and smoking cessation, and the DRD2 Taq1A and CYP2A6 reduced-activity polymorphisms and cigarette consumption. The evidence for an effect of specific genes was modest, however, and evidence indicated substantial between-study heterogeneity in most cases, with the exception of the effects of the 5HTT and CYP2A6 genes on smoking cessation. When a random-effects model was applied to analyses in which evidence indicated significant heterogeneity, the effects were in all cases no longer statistically significant. The evidence for a contribution of specific genes to smoking behavior remains modest. Implications for the design of future studies are discussed, such as the need for the development of more specific phenotypes to increase the genetic signal in candidate gene studies.     

The effectiveness of smoking cessation interventions prior to surgery: a systematic review.

The objective of this review was to evaluate the effectiveness of smoking cessation interventions prior to surgery and examine smoking cessation rates at 6 months follow-up. The Cochrane Library Database, PsycINFO, EMBASE, Medline, and Cinahl databases were searched using the terms: smok$, smoking cessation, tobacco, cigar$, preop$, operati$, surg$, randomi*ed control$ trial, intervention, program$, cessation, abstinen$, quit. Further articles were obtained from reference lists. The search was limited to articles on adults, written in English and published up to December 2006. Only randomized control trials (RCTs) that incorporated smoking cessation interventions to patients awaiting elective surgery were included. Seven studies met the inclusion criteria. Methodological quality was assessed by all the authors. The findings revealed that short-term quit rates (or a reduction by more than half of normal daily rate) ranged from 18% to 93% in patients receiving a smoking intervention (mean 55%), compared with a range of 2%-65% of controls (mean = 27.7%). Two studies examined smoking status at 6 months but these revealed no significant difference in abstinence rates between patients who had received an intervention and those that had not. Studies that incorporated counseling in addition to nicotine replacement therapy appeared to show greater benefits. It is concluded that smoking cessation interventions prior to surgery are effective in helping patients to quit smoking. However, such effects appear to be short-lived. Future research needs to examine intervention and patient factors to see whether tailoring the smoking cessation intervention specifically to the patient improves overall abstinence rates.     

Factors associated with smoking in Asian American adults: a systematic review

This review systematically examined the factors associated with smoking in Asian American adults (aged > or =17 years). A total of 21 quantitative studies published in peer-reviewed journals from 1997 to 2006 were reviewed and abstracted using the matrix method. Statistically significant factors reported by the studies were summarized. Methodological quality of the studies also was assessed (maximum possible score = 10). Acculturation and education were the most frequently reported factors (n = 10, 47.6%). Acculturation was negatively associated with men's smoking but was positively associated with women's smoking. Education was uniformly found to be negatively related to smoking. Age was reported to have either a positive or a negative relationship with smoking (n = 9, 42.9%). Men were more likely to smoke than women (n = 7, 33.3%). The mean methodological score of the reviewed studies was 4.14 (on a scale of 1-10 points; SD = 1.62; range = 2-8). Health promotion professionals need to consider the summarized factors associated with Asian American adults' smoking behavior when planning smoking prevention programs and when recruiting participants for smoking cessation programs. When addressing acculturation, program planners should design different health education materials and use different strategies for men and women. To identify, understand, and incorporate essential factors into effective interventions, future studies should aim at higher methodological quality by using longitudinal design and increasing the use of theory, the test of data validity and reliability, and the report of effect sizes.     

Spirometry as a motivational tool to improve smoking cessation rates: a systematic review of the literature.

Obtaining spirometric testing and providing those results to individuals who smoke has been advocated as a motivational tool to improve smoking cessation. However, its effectiveness is not known. We conducted a systematic review to determine if this approach improves rates of smoking cessation. Data sources included MEDLINE (1966 to October 2005), the Cochrane Library, and experts in the field. Eligible randomized controlled trials (RCTs) enrolled at least 25 smokers per arm, evaluated spirometry with associated counseling or in combination with other treatments, followed subjects at least 6 months, and provided smoking abstinence rates. Results from nonrandomized studies also were summarized. The primary outcome was patient-reported long-term (at least 6 months) sustained abstinence with biological validation. Additional outcomes included self-reported abstinence and point-prevalence abstinence. Seven RCTs (N = 6,052 subjects) met eligibility criteria. Follow-up duration ranged from 9 to 36 months. In six trials, the intervention group received concomitant treatments previously demonstrated to increase cessation independently. The range of abstinence was 3%-14% for control subjects and 7%-39% among intervention groups, statistically significantly in favor of intervention in four studies. The only RCT that assessed the independent contribution of spirometry in combination with counseling demonstrated a nonsignificant 1% improvement in patient-reported point-prevalence abstinence at 12 months in the group that received spirometry plus counseling versus counseling alone (6.5% versus 5.5%). Findings from observational studies were mixed, and the lack of controls makes interpretation problematic. Available evidence is insufficient to determine whether obtaining spirometric values and providing that information to patients improves smoking cessation compared with other smoking cessation methods. Spirometric values are of limited benefit as a predictor of smoking cessation or as a tool to "customize" smoking cessation strategies.     

Nortriptyline for smoking cessation: a review.

This article reviews the efficacy of nortriptyline for smoking cessation based on a meta-analysis of the Cochrane Library. Six placebo-controlled trials have shown nortriptyline (75-100 mg) doubles quit rates (OR = 2.1). Between 4% and 12% of smokers dropped out because of adverse events, but no serious adverse events occurred. The efficacy of nortriptyline did not appear to be related to its antidepressant actions. Nortriptyline is an efficacious aid to smoking cessation with a magnitude of effect similar to that for bupropion and nicotine replacement therapies. Whether nortriptyline produces serious side effects at these doses in healthy, nondepressed smokers remains unclear because it has been tested in only 500 smokers. The finding that nortriptyline and bupropion are effective for smoking cessation but that selective serotonin-reuptake inhibitors are not suggests that dopaminergic or adrenergic, but not serotonergic, activity is important for cessation efficacy. Until further studies can verify a low incidence of significant adverse events, nortriptyline should be a second-line treatment for smoking cessation.     

Ad lib smoking in post-traumatic stress disorder: an electronic diary study

Using ambulatory methods for 1 week of monitoring, this study investigated the association between smoking and situational cues in 22 smokers with post-traumatic stress disorder (PTSD) and 23 smokers without PTSD. Generalized estimating equations contrasted 1,759 smoking and 1,088 nonsmoking situations by group status controlling for multiple covariates. PTSD smokers reported higher stress and PTSD symptoms across daily activities. For all smokers, higher nicotine dependence, craving, food and caffeine consumption, and being outside were related to smoking. PTSD smokers were more likely to smoke when experiencing PTSD symptoms, anxiety, and stress. Following smoking, smokers with PTSD reported a significant reduction in negative affect. These results are consistent with previous ambulatory findings regarding mood in smokers, and underscore that in smokers with PTSD, PTSD symptom variables as well as stress and anxiety are significantly associated with ad lib smoking.     

Effectiveness of biomedical risk assessment as an aid for smoking cessation: a systematic review

Objective

To determine the efficacy of biomedical risk assessment (eg, exhaled carbon monoxide (CO), or genetic susceptibility to lung cancer) as an aid for smoking cessation.

Data sources

Cochrane Tobacco Addiction Group Specialized Register, Cochrane Central Register of Controlled Trials, Medline (1966–2004) and EMBASE (1980–2004).

Study selection

Randomised controlled smoking cessation interventions using biomedical tests with at least 6 months follow‐up.

Data extraction

Two reviewers independently screened all search results (titles and abstracts) for possible inclusion. Each reviewer then extracted data from the selected studies, and assessed their methodological quality based on the CONSORT (Consolidated Standards of Reporting Trials) statement criteria.

Data synthesis

Of 4049 retrieved references, eight trials were retained for data extraction and analysis. Three trials isolated the effect of exhaled CO on smoking cessation rates resulting in the following ORs and 95% CIs: 0.73 (0.38 to 1.39), 0.93 (0.62 to 1.41) and 1.18 (0.84 to 1.64). Measurement of exhaled CO and spirometry were used together in three trials, resulting in the following ORs (95% CI): 0.60 (0.25 to 1.46), 2.45 (0.73 to 8.25) and 3.50 (0.88 to 13.92). Spirometry results alone were used in one other trial with an OR (95% CI) of 1.21 (0.60 to 2.42). Ultrasonography of carotid and femoral arteries performed on light smokers gave an OR (95% CI) of 3.15 (1.06 to 9.31).

Conclusions

Scarcity and limited quality of the current evidence does not support the hypothesis that biomedical risk assessment increases smoking cessation as compared with the standard treatment.Despite increasing scientific knowledge about health hazards due to cigarette consumption, there is, in many countries, an increase in the prevalence of smoking among young people.^1,2 The gap between knowledge and smoking cessation has been attributed, partly, to smokers'' underestimation of their personal risks of smoking‐related illness.^3,4A possible strategy for increasing quit rates might be to provide a personalised feedback on the physical effects of smoking by physiological measurements. We can distinguish three different types of feedback: the first one explores biomarkers of smoking exposure (cotinine and carbon monoxide (CO)); the second one gives information on smoking‐related disease risk (eg, lung cancer susceptibility according to CYP2D6 genotyping)⁵; and the third one depicts smoking‐related harm (eg, atherosclerotic plaque and impaired lung functions).⁶ The rationale for such interventions is to promote risk awareness and motivation to accelerate changes in smoking‐behaviour.^7,8Individual studies have provided conflicting data on the effect of physiological feedback.^{9,10,11,12,13,14,15,16,17} We aimed to review the data on smoking cessation rates from controlled trials using feedback on the physiological effects of smoking or on the genetic susceptibility to smoking‐related diseases. This article is a shortened version of our Cochrane review.¹⁸     

Attention-deficit/hyperactivity disorder (ADHD) and obesity: a systematic review of the literature

Recent studies suggest a possible comorbidity between Attention-Deficit/Hyperactivity Disorder (ADHD) and obesity. To gain insight into this potential association, we performed a systematic review of the literature excluding case reports, non-empirical studies, and studies not using ADHD diagnostic criteria. Empirically based evidence suggests that obese patients referred to obesity clinics may present with higher than expected prevalence of ADHD. Moreover, all reviewed studies indicate that subjects with ADHD are heavier than expected. However, data on the prevalence of obesity in subjects with ADHD are still limited. As for the mechanisms underlying the potential association between ADHD and obesity, ADHD might lead to obesity via abnormal eating behaviors, impulsivity associated with binge eating might contribute to ADHD in obese patients, or, alternatively, both obesity and ADHD might be the expression of common underlying neurobiological dysfunctions, at least in a subset of subjects. In patients with obesity and ADHD, both conditions might benefit from common therapeutic strategies. Further empirically based studies are needed to understand the potential comorbidity between obesity and ADHD, as well as the possible mechanisms underlying this association. This might allow a more appropriate clinical management and, ultimately, a better quality of life for patients with both obesity and ADHD.     

Effects of nicotine and smoking on event-related potentials: a review.

Event-related potentials can serve as an adjunct to reaction time in elucidating the effects of nicotine on rapid human information processing. We review the literature related to nicotine and event-related potentials. Although evidence indicates that, in the visual modality, nicotine enhances early perceptual processing and in certain instances speeding stimulus evaluation, the bulk of nicotine's effects seem to be on enhancing response preparation and response execution.     

Waterpipe smoking and nicotine exposure: a review of the current evidence.

The waterpipe, also known as shisha, hookah, narghile, goza, and hubble bubble, has long been used for tobacco consumption in the Middle East, India, and parts of Asia, and more recently has been introduced into the smokeless tobacco market in western nations. We reviewed the published literature on waterpipe use to estimate daily nicotine exposure among adult waterpipe smokers. We identified six recent studies that measured the nicotine or cotinine levels associated with waterpipe smoking in four countries (Lebanon, Jordan, Kuwait, and India). Four of these studies directly measured nicotine or cotinine levels in human subjects. The remaining two studies used smoking machines to measure the nicotine yield in smoking condensate produced by the waterpipe. Meta-analysis of the human data indicated that daily use of the waterpipe produced a 24-hr urinary cotinine level of 0.785 microg/ml (95% CI = 0.578-0.991 microg/ml), a nicotine absorption rate equivalent to smoking 10 cigarettes/day (95% CI = 7-13 cigarettes/day). Even among subjects who were not daily waterpipe smokers, a single session of waterpipe use produced a urinary cotinine level that was equivalent to smoking two cigarettes in one day. Estimates of the nicotine produced by waterpipe use can vary because of burn temperature, type of tobacco, waterpipe design, individual smoking pattern, and duration of the waterpipe smoking habit. Our quantitative synthesis of the limited human data from four nations indicates that daily use of waterpipes produces nicotine absorption of a magnitude similar to that produced by daily cigarette use.     

Invited review: Lethal heat stress: The putative pathophysiology of a deadly disorder in dairy cattle

Heat stress (HS) reduces production and efficiency in almost every metric of the dairy operation, and it thus compromises profitability and sustainability. If the magnitude of HS progresses, it can become lethal. Death can occur acutely or days following the heat load, even if environmental conditions have become nonstressful. Consequently, lethal heat stress (LHS) is often difficult to identify and almost always misdiagnosed. The precise mechanisms of death when dairy cows succumb to LHS has not been fully elucidated or documented, but the pathophysiology of LHS appears to be conserved among several species. The unique digestive physiology of ruminants adds additional layers of complexity that contribute to failure of multiple systems involved with LHS. Consequently, the ostensible etiology and pathogenesis of LHS described herein is extended from the physiological adaptations cows use to survive HS and pertinent pathology extrapolated from other species. The multifactorial causes of death likely involve dysfunction and imbalance of several interdependent systems as follows: (1) electrolyte dyshomeostasis, (2) unstable blood pH, (3) gastrointestinal tract hyperpermeability, (4) sepsis, (5) severe immune activation-induced inflammation, (6) disseminated intravascular hypercoagulation, (7) systemic endothelial permeability, (8) multiple organ failure, and (9) circulatory failure. Having a better understanding of the mechanisms of LHS will improve diagnosis, enable a more accurate prognosis, and provide insight into strategies aimed at preventing dairy cow mortality and morbidity.     

Reconsidering stress and smoking: a qualitative study among college students

Background

Although it is widely acknowledged among adult smokers that increases in smoking are often precipitated by stressful events, far less attention has been given to smoking during times of stress among youth.

Aims

To address this gap by drawing attention to the social utility of smoking in contexts associated with stress among college students.

Design

Face‐to‐face semistructured interviews with college freshmen at a large midwestern university in the US.

Participants

Male and female low‐level smokers (n = 24), defined as those who reported regular weekday smoking (typically 3–4 cigarettes a day) and smoking at parties on weekends, were interviewed once in person. In addition, 40 brief interviews with smokers were conducted during final examination.

Measurements

Interviews focused on a range of issues including current smoking behaviour and reasons for smoking. As part of the interview, students were given a deck of cards that listed a range of reasons for smoking. Participants were asked to select cards that described their smoking experience in the past 2 weeks. Those who selected cards that indicated smoking when stressed were asked to explain the reasons why they did so.

Results

A review of qualitative responses reveals that smoking served multiple functions during times of stress for college students. Cigarettes are a consumption event that facilitates a brief social interaction during study times when students feel isolated from their friends. Cigarettes also serve as an idiom of distress, signalling non‐verbally to others that they were stressed. Students described smoking to manage their own stress and also to help manage “second‐hand stress” from their friends and classmates.

Conclusions

Moving away from an individual‐focused analysis of stress to a broader assessment of the social contexts of smoking provides a more nuanced account of the multifunctionalilty of cigarettes in students'' lives. Qualitative research draws attention to issues including the need for smoking and socialising during examination time, smoking as a way to take a break and refocus, notions of second‐hand stress and smoking to manage social relationships.In the past decade, several US‐based studies have reported significant levels of smoking among college students, with approximately 30% of college students reporting having smoked in the past 30 days, and 40% reporting having smoked in the past year.^1,2 Studies have found that a majority of college students who smoke are social smokers, meaning that they smoke more often with others than when alone, particularly when drinking, and that they smoke at low levels.^3,4 To understand better the patterns of low‐level tobacco use, qualitative research was conducted to examine closely the contexts in which students smoked. It has been suggested that a better understanding of the social context of smoking may help enhance tobacco control research and practice.⁵ Two broad contexts that begged consideration were positive social contexts in which tobacco use occurred (such as parties where alcohol was consumed), and contexts associated with stress, be this stressful life events (such as the taking of exams) or stressful events related to the management of social relationships and shifts in identity at this time of transition in life.This article highlights major findings of qualitative research on smoking in contexts associated with stress among college students. It is well established in the general population that increases in smoking are often precipitated by stressful events.^6,7 We draw attention to the social utility of smoking in contexts associated with stress, acknowledging that tobacco use also has psychological and physiological effects when used as a form of stress management and self‐medication.Three major issues guided the research: (1) to explore the extent to which students use smoking as a multifunctional tool for stress management; (2) to determine whether students use smoking as an idiom of distress and a means of showing empathy when a friend is under stress; and (3) to provide details on the complex of motivations that lead students to smoke during examination time.     

Effects of preoperative smoking cessation on the incidence and risk of intraoperative and postoperative complications in adult smokers: a systematic review

Objectives

To establish the effect of preoperative smoking cessation on the risk of postoperative complications, and to identify the effect of the timing of preoperative cessation.

Data sources

The Cochrane Library Database, PsycINFO, EMBASE, Medline, and CINAHL databases were searched, using the terms: “smoking”, “smoking‐cessation”, “tobacco‐use”, “tobacco‐abstinence”, “cigarett$”, “complication$”, “postoperative‐complication$”, “preoperative”, “perioperative” and “surg$”. Further articles were obtained from reference lists. The search was limited to articles on adults, written in English and published up to November 2005.

Study selection

Prospective cohort designs exploring the effects of preoperative smoking cessation on postoperative complications were included. Two reviewers independently scanned abstracts of relevant articles to determine eligibility. Lack of agreement was resolved through discussion and consensus. Twelve studies met the inclusion criteria.

Data extraction

Methodological quality was assessed by both reviewers, exploring validation of smoking status, clear definition of the period of smoking cessation, control for confounding variables and length of follow‐up.

Data synthesis

Only four of the studies specified the exact period of smoking cessation, with six studies specifying the length of the follow‐up period. Five studies revealed a lower risk or incidence of postoperative complications in past smokers than current smokers or reported that there was no significant difference between past smokers and non‐smokers.

Conclusions

Longer periods of smoking cessation appear to be more effective in reducing the incidence/risk of postoperative complications; there was no increased risk in postoperative complications from short term cessation. An optimal period of preoperative smoking cessation could not be identified from the available evidence.     

Food security governance: a systematic literature review

The role of governance has been receiving increasing attention from food security scholars in recent years. However, in spite of the recognition that governance matters, current knowledge of food security governance is rather fragmented. To provide some clarity in the debate about the role of governance in addressing food (in)security, this paper reports the results of a systematic review of the literature. The synthesis revolves around seven recurring themes: i) the view of governance as both a challenge and solution to food security; ii) a governability that is characterized by high degrees of complexity; iii) failures of the current institutional architectures; iv) the arrival of new players at the forefront; v) calls for coherency and coordination across multiple scales; vi) variation and conflict of ideas; and vii) calls for the allocation of sufficient resources and the integration of democratic values in food security governance. Two lines of discussion of this synthesis are raised. First, the researcher argues that a large proportion of the food security governance literature is characterized by an optimist governance perspective, i.e., a view of governance as a problem-solving mechanism. Complementing this body of literature with alternative governance perspectives in future research may strengthen current understandings of food security governance. Approaching food security as a ‘wicked problem’ could provide valuable insights in this respect. Second, food security governance as a research field could make headway by engaging in further empirical investigation of current governance arrangements, particularly at sub-national levels.     

Personality and smoking status: a meta-analysis.

We used meta-analytic techniques in an attempt to clarify the strength and direction of the association between smoking status and personality, which narrative reviews have indicated remains a largely inconsistent literature. Included were cross-sectional studies that reported personality data for healthy, adult smokers and nonsmokers using measures of personality traits derived from Eysenck's tripartite taxonomy of human personality. Of the 25 studies that contributed to the meta-analysis, 22 reported data on smoking status and extraversion and 22 reported data on smoking status and neuroticism. Meta-analysis using a fixed-effects framework indicated a significant difference between smokers and nonsmokers on both extraversion (p<.001) and neuroticism (p<.001) traits, which remained significant when a random-effects framework was used to accommodate significant between-study heterogeneity. These data from cross-sectional observational studies published between 1972 and 2001 indicate that both increased extraversion and increased neuroticism are associated with an increased likelihood of being a smoker rather than a nonsmoker, although in both cases the effect sizes indicated by the meta-analysis were small. We found no evidence that the strength of these associations varied with year of publication.