Salivary cotinine concentration versus self-reported cigarette smoking: Three patterns of inconsistency in adolescence.

The present study examined the extent and sources of discrepancies between self-reported cigarette smoking and salivary cotinine concentration among adolescents. The data are from household interviews with a cohort of 1,024 adolescents from an urban school system. Histories of tobacco use in the last 7 days and saliva samples were obtained. Logistic regressions identified correlates of three inconsistent patterns: (a) Pattern 1-self-reported nonsmoking among adolescents with cotinine concentration above the 11.4 ng/mg cutpoint (n = 176), (b) Pattern 2-low cotinine concentration (below cutpoint) among adolescents reporting having smoked within the last 3 days (n = 155), and (c) Pattern 3-high cotinine concentration (above cutpoint) among adolescents reporting not having smoked within the last 3 days (n = 869). Rates of inconsistency were high among smokers defined by cotinine levels or self-reports (Pattern 1 = 49.1%; Pattern 2 = 42.0%). Controlling for other covariates, we found that reports of nonsmoking among those with high cotinine (Pattern 1) were associated with younger age, having few friends smoking, little recent exposure to smokers, and being interviewed by the same interviewer as the parent and on the same day. Low cotinine concentration among self-reported smokers (Pattern 2) was negatively associated with older age, being African American, number of cigarettes smoked, depth of inhalation, and exposure to passive smoke but positively associated with less recent smoking and depressive symptoms. High cotinine concentrations among self-reported nonsmokers was positively associated with exposure to passive smoke (Pattern 3). The data are consonant with laboratory findings regarding ethnic differences in nicotine metabolism rate. The inverse relationship of cotinine concentration with depressive symptoms has not previously been reported. Depressed adolescent smokers may take in smaller doses of nicotine than nondepressed smokers; alternatively, depressed adolescents may metabolize nicotine more rapidly.     

Sex-related differences in serum cotinine concentrations in daily cigarette smokers

Self-reported use of cigarettes generally underestimates the true cigarette exposure of smokers. Serum cotinine is considered the best biomarker to evaluate tobacco exposure. This study determined whether or not there were any significant differences in serum cotinine concentrations between men and women when they reported smoking the same number of cigarettes per day. We analyzed cotinine and tobacco consumption data on 680 women and 840 men, aged 20 years or older, who smoked at least 100 cigarettes during their lifetime and were still actively smoking at the time of the National Health and Nutrition Examination Surveys (1999-2002). Overall, compared with men, women reported smoking fewer cigarettes per day (16.1 vs. 18.7, p<.001) and had lower serum cotinine concentrations (1163.3 nmol/L vs. 1343.9 nmol/L, p<.001). Women were more likely than men to smoke filtered (p = .018) and mentholated (p<.001) cigarettes. After adjustment for the number of cigarettes smoked per day, age, race, body mass index, poverty status, the use of either menthol or regular cigarettes, and the nicotine content in cigarettes, female compared with male smokers had lower serum cotinine concentrations (difference of 117.6 nmol/L; 95% CI = 42.6-192.6, p = .003). The difference was particularly notable in moderate to heavy smokers (i.e., those who smoked more than 15 cigarettes/day). These findings indicate that significant sex-related differences exist in serum cotinine levels among smokers, which suggests that self-reports may overestimate cigarette exposure in women compared with men.     

Secondhand smoke exposure and C-reactive protein levels in youth.

Using data from the National Health and Nutrition Examination Survey (NHANES, 1999-2002), we examined the association of secondhand tobacco exposure, estimated by serum cotinine, with serum C-reactive protein (CRP) concentrations in nonsmoking participants, aged 6-18 years. The association between serum cotinine and serum CRP was analyzed using multiple linear regression, with adjustment for other study variables. All analyses used weighted data and adjustments for design effects. Multiple regression analysis indicated that a change in serum cotinine of 0.5 ng/ml was associated with a 0.96 mg/dl change in CRP (95% CI=0.93-1.00), even after adjustment for age, white blood cell count, and body mass index percentile. We found a significant association between secondhand smoke exposure, assessed by serum cotinine, and elevated serum CRP among nonsmoking youth. Secondhand smoke exposure may pose an important long-term cardiovascular risk for children and adolescents.     

Cotinine levels in relation to smoking behavior and addiction in young adolescent smokers.

The goal of this study was to identify associations among self-reported nicotine exposure, nicotine addiction, and actual nicotine intake as measured by salivary cotinine levels in adolescent smokers. A total of 170 adolescent smokers with a mean age of 15 years were recruited from seven northern Californian public high schools. Data were collected on smoking behaviors, addiction, craving, and withdrawal. Nicotine dependence was assessed using a modified teen Fagerstr?m Tolerance Questionnaire (mtFTQ), a modified Nicotine Dependence Syndrome Scale (mNDSS), and a simple self-rating. Withdrawal was assessed using the Minnesota Withdrawal Questionnaire, and craving was assessed using a survey created by the authors. Salivary cotinine levels were collected from and analysed in participants who self-identified as smokers; data from the 54 participants who smoked in the past 4 days and whose salivary cotinine levels were greater than 0.1 ng/ml were used in the analysis. Among this group of adolescent smokers, the mean number of cigarettes smoked per day was 3.51 (SD = 3.44) and the mean level of salivary cotinine was 44.1 ng/ml (Mdn = 24.2). Even at this low level of nicotine exposure, cotinine was highly correlated with measures of nicotine dependence such as the mtFTQ (r = 0.497, p = .001), NDSS (r = 0.439, p = .002), timing of craving in the morning (r = -0.601, p = .000), and self-rated addiction (r = 0.562, p = .000). Most interesting, cotinine levels reached a plateau at around 4-5 cigarettes/day.     

Determinants of salivary cotinine levels among current smokers in Mexico.

The present study describes salivary cotinine levels and their relationship to cigarettes smoked per day in Mexican smokers. Using a sampling strategy based on the number of cigarettes per day, we recruited 1,222 smokers from Mexico City and the state of Morelos in Mexico during 1999. Smoking behaviors and other factors known to affect nicotine intake and cotinine level were identified in an interview using a standardized questionnaire. Salivary cotinine was measured by capillary gas chromatography with nitrogen-phosphorus detection. We used generalized additive models to describe the relationship between salivary cotinine levels and variables of interest. The mean age of the population was 39.7 years (SD=15.6 years), with a mean cotinine level of 194.7 ng/ml (SD=134.8; range=10.1-767). Participants smoked a mean of 15.5 cigarettes per day (SD=11.3). Salivary cotinine and cigarettes smoked per day were positively related, although the association was not linear, flattening above 20 cigarettes per day. After adjusting for cigarettes per day, we found that significant predictors of cotinine levels included age, body mass index, cigarette producer, and smoking behavior variables. These results may have implications for dosing with nicotine medications to aid smoking cessation in Mexican smokers and suggest that whether the cigarette is labeled light or regular has no relationship to nicotine dose from smoking cigarettes.     

The influence of gender, race, and menthol content on tobacco exposure measures.

Research has suggested that race, gender, and menthol cigarette use influence tobacco-smoke exposure measures and smoking-related disease risk. For example, a high proportion of Black smokers prefer menthol cigarettes and, despite smoking fewer cigarettes per day (CPD) than do Whites, tend to have higher cotinine levels. Additionally, Black males are more at risk for smoking-related lung cancer. High cotinine levels and smoking menthol cigarettes may lead to higher toxin intake, which contributes to increased disease risk. We explored the relationship between tobacco exposure variables (i.e., cotinine, CPD, carbon monoxide [CO], nicotine content, and nicotine dependence) with respect to race, gender, and menthol content in a sample of 307 smokers recruited from the greater Boston area to participate in a smoking cessation treatment trial. The pattern of correlations between tobacco exposure measures and cotinine showed a consistently positive correlation between cotinine and CO in all smokers and a correlation between cotinine and CPD in those who smoked nonmenthol cigarettes. Cotinine and CPD correlations varied by gender and race among menthol cigarette smokers. Consistently, we found a significant gender x race x menthol interaction on salivary cotinine level as well as cotinine/CPD ratio. These findings suggest that the relationship between number of cigarettes consumed and salivary cotinine is more complex than previously believed. It is not sufficient to look at race alone; researchers and clinicians need to look at race and gender concurrently, as well as type of cigarette consumed.     

Smoke constituent exposure and smoking topography of adolescent daily cigarette smokers.

Adolescent smoking prevalence is a major health concern, with 24.4% reporting smoking in the past 30 days and 15.8% considered daily smokers. The purpose of this study was to characterize biobehavioral nicotine dependence, smoke constituent exposure and smoking topography in adolescent daily smokers. Relationships among biological markers of nicotine dependence (nicotine boost, carbon monoxide [CO] boost and cotinine levels) with existing self-report measures (modified Fagerstr?m Tolerance Questionnaire [mFTQ] and the motivations for smoking scale) were examined. Gender differences were characterized. Fifty adolescents 13-18 years old were recruited for the study, 50% female. CO, plasma nicotine levels pre- and postcigarette, cotinine, and smoking topography were measured during a smoking bout with participant's usual cigarette. Average CO boost, pre- to postcigarette was 7.2 + 3.6 ppm, baseline cotinine level averaged 224.0 +/- 169.6 ng/ml and nicotine boost averaged 23.4 +/- 21.7 ng/ml. Mean puffs per cigarette was 14.2 +/- 6.3. Males had significantly higher total puff volumes, but similar smoke constituent exposure to females, and higher handling of cigarettes as smoking motive. In regression analysis, 35% of variance in tobacco use, as indicated by baseline cotinine concentration, was explained by maximum puff duration, postcigarette CO level, and nicotine dependence, as measured by the mFTQ. Results indicated adolescents had considerable smoke constituent exposure and nicotine dependence suggesting the importance of appropriate smoking cessation treatment.     

Urinary tobacco-specific nitrosamines and 4-aminobiphenyl hemoglobin adducts measured in smokers of either regular or light cigarettes.

Cigarette brands may differ in their reported yields of "tar" as determined by the Federal Trade Commission smoking-machine method. Brands with relatively lower tar and nicotine yields often are described as light cigarettes. Smokers of light cigarettes generally maintain a nicotine intake comparable to that of smokers of regular cigarettes through compensatory smoking behaviors, but similar data have not been reported for carcinogen biomarkers. In the present study we measured serum cotinine concentrations (a marker of nicotine exposure), urinary levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, a tobacco-specific nitrosamine [TSNA]), and hemoglobin adducts of 4-aminobiphenyl (4-ABP) in 150 smokers of either regular or light cigarettes. The TSNA and aromatic amines are known carcinogens in tobacco smoke. Multiple regression models were developed for each of the analytes and used to calculate adjusted geometric means. We found no significant differences in the levels of these biomarkers between customary users of light and regular cigarettes. Thus the concentrations of the carcinogen biomarkers NNAL and 4-ABP in the smokers who regularly smoked light cigarettes were essentially the same as those in the smokers who chose regular cigarettes.     

Higher nicotine and carbon monoxide levels in menthol cigarette smokers with and without schizophrenia.

This study examined whether smoking menthol cigarettes was associated with increased biochemical measures of smoke intake. Expired carbon monoxide (CO) and serum nicotine and cotinine were measured in 89 smokers with schizophrenia and 53 control smokers immediately after smoking an afternoon cigarette. Serum nicotine levels (27 vs. 22 ng/ml, p = .010), serum cotinine levels (294 vs. 240 ng/ml, p = .041), and expired CO (25 vs. 21 ppm, p = .029) were higher in smokers of menthol compared with nonmenthol cigarettes, with no differences in 3-hydroxycotinine/cotinine ratios between groups when controlling for race. Backward stepwise linear regression models showed that, in addition to having a diagnosis of schizophrenia, smoking menthol cigarettes was a significant predictor of nicotine and cotinine levels. Individuals with schizophrenia or schizoaffective disorder smoked more generic or discount value brands (Basic, Doral, Monarch, USA, Wave, others) compared with control smokers (28% vs. 6%, p = .002) but did not smoke more brands with high nicotine delivery as estimated by the U.S. Federal Trade Commission method. Although rates of mentholated cigarette smoking were not higher in smokers with schizophrenia overall, they were significantly higher in non-Hispanic White people with schizophrenia compared with controls of the same ethnic/racial subgroup (51% vs. 28%, p<.0001). The higher exhaled CO in menthol smokers suggests that the higher nicotine levels are at least partly related to increased intake of smoke from menthol cigarettes, although menthol-mediated inhibition of nicotine metabolism also may be a factor. Menthol is an important cigarette additive that may help explain why some groups have lower quit rates and more smoking-caused disease.     

Smoking behaviour and toxin exposure during six weeks use of a potential reduced exposure product: Omni

Objective: To determine smoking behaviour, acceptability, and toxin exposure when smokers switch to the potential reduced exposure product—Omni cigarette.

Design: 12 week randomised, crossover study of Omni versus own cigarettes.

Participants: 19 light/ultralight and 15 regular smokers.

Outcomes: Cigarettes/day, smoking topography, craving, withdrawal symptoms, urinary cotinine plus its glucuronide (total cotinine), nicotine plus its glucuronide (total nicotine), and carcinogen metabolites (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol plus its glucuronides and 1-hydroxypyrene).

Results: When switched to Omni, smokers smoked the same number of cigarettes/day, smoked Omni cigarettes less intensely (total puff volume = –11%) and had slightly lower total cotinine (–18%) levels than their own cigarettes, but had a slightly greater carbon monoxide boost/cig (+21%). Craving and withdrawal ratings were similar with Omni and own cigarettes. Carcinogen metabolite levels were somewhat but not significantly lower with Omni. About half of smokers rated Omni as better for their health and about two thirds stated it was weaker and worse tasting than their own cigarettes.

Conclusions: Although Omni may be an adequate behavioural and pharmacological substitute for traditional cigarettes, it may not decrease carcinogen exposure and may increase carbon monoxide. Replications with larger sample sizes and longer follow up are needed. These results indicate the need for regulation of reduced exposure and reduced risk claims.

     

Tobacco industry consumer research on socially acceptable cigarettes

Objective: To describe tobacco industry consumer research to inform the development of more "socially acceptable" cigarette products since the 1970s. Methods: Analysis of previously secret tobacco industry documents. Results: 28 projects to develop more socially acceptable cigarettes were identified from Philip Morris, RJ Reynolds, British American Tobacco, and Lorillard tobacco companies. Consumer research and concept testing consistently demonstrated that many smokers feel strong social pressure not to smoke, and this pressure increased with exposure to smoking restrictions. Tobacco companies attempted to develop more socially acceptable cigarettes with less visible sidestream smoke or less odour. When presented in theory, these product concepts were very attractive to important segments of the smoking population. However, almost every product developed was unacceptable in actual product tests or test markets. Smokers reported the complete elimination of secondhand smoke was necessary to satisfy non-smokers. Smokers have also been generally unwilling to sacrifice their own smoking satisfaction for the benefit of others. Many smokers prefer smoke-free environments to cigarettes that produce less secondhand smoke. Conclusions: Concerns about secondhand smoke and clean indoor air policies have a powerful effect on the social acceptability of smoking. Historically, the tobacco industry has been unable to counter these effects by developing more socially acceptable cigarettes. These data suggest that educating smokers about the health dangers of secondhand smoke and promoting clean indoor air policies has been difficult for the tobacco industry to counter with new products, and that every effort should be made to pursue these strategies.     

Digital image analysis of cigarette filter staining to estimate smoke exposure.

Sufficient variation exists in how people smoke each cigarette that the number of cigarettes smoked daily and the years of smoking represent only crude measures of exposure to the toxins in tobacco smoke. Previous research has shown that spent cigarette filters can provide information about how individuals smoke cigarettes. Digital image analysis has been used to identify filter vent blocking and may also provide an inexpensive, unobtrusive index of overall smoke exposure. A total of 1,124 cigarette butts smoked by 53 participants in a smoking topography study were imaged and analyzed. Imaging showed test-retest reliability of more than 95% among those smoking their own brand. Mean color scores (CIELAB system) showed acceptable stability (>.60) across days, paralleling the basic stability of smoking topography measures across waves. A principal components scoring showed that center tar staining, edge tar staining, and their interaction were significantly related to total smoke volume, accounting for 73% of the variation. Estimated smoke volume was a significant predictor of salivary cotinine when accounting for cigarettes smoked per day. These data suggest that digital image analysis of spent cigarette butts can serve as a reliable proxy measure of total smoke volume.     

Passive smoking in the home: plasma cotinine concentrations in non-smokers with smoking partners

BACKGROUND: Risks of lung cancer and of heart disease attributable to passive smoking have been evaluated mainly in non-smokers married to smokers, but there has been little quantitative assessment of the extent of exposure in marriage partners as indicated by markers of inhaled smoke dose. OBJECTIVE: To relate plasma cotinine concentrations in non-smoking English adults to the smoking behaviour of their partners and to demographic and other factors. DATA: Population survey. Data from two years (1994 and 1996) of the Health Survey for England. MAIN OUTCOME MEASURES: Plasma cotinine concentrations in non-smoking adults married to or cohabiting with a partner. RESULTS: There was a strong dose-response relation between cotinine concentrations in non-smoking adults and the smoking behaviour of their partners, rising from a geometric mean of 0.31 ng/ml in those with non-smoking partners to 1.99 ng/ml in those whose partners smoked 30 or more cigarettes per day. In addition, exposure was greater in men, in the autumn and winter, and in those living in more disadvantaged circumstances, and there was an increasing gradient of exposure from the south to the north of the country. On average, cotinine concentrations in non-smokers with a smoking partner were 0.6-0.7% of those in cigarette smokers. CONCLUSIONS: If cotinine is taken as a measure of risk relevant dose, the implied increase in risk of lung cancer in non-smokers with smoking partners is consistent with the risk observed in epidemiological studies. Smoking by partners in the home is a major source of non-smoking adults' exposure to passive smoking.     

Measuring environmental tobacco smoke exposure in infants and young children through urine cotinine and memory-based parental reports: empirical findings and discussion

OBJECTIVE: This study examined the reliability and potential biases of two urine collection methods from which cotinine measures were obtained and the validity of memory-based parental reports of their children's exposure to environmental tobacco smoke (ETS). DESIGN: Structured interviews were conducted with mothers of infants and young children to obtain memory-based estimates of recent ETS exposure. Urine samples were collected through standard and cotton roll collection methods for cotinine analysis. SETTING: All interviews took place at an off-campus research facility. Urine samples were collected at the study office or the subjects' homes. PARTICIPANTS: Mothers were recruited from San Diego county sites of the Women, Infants, and Children (WIC) Supplemental Food and Nutrition Program. Sample 1 (infants) consisted of eight boys and eight girls aged 1-44 months (mean = 12.6 months). Sample 2 (children) included 10 boys and 10 girls aged 3-8 years (mean = 61.2 months). MAIN OUTCOME MEASURES: Urine cotinine and memory-based parent reports of ETS exposure from structured interviews. RESULTS: There was overall high reliability for urine cotinine measures and no effect of collection method on urine cotinine levels. Memory-based reports obtained from smoking mothers showed moderately strong and consistent linear relationships with urine cotinine measures of their infants and children (r = 0.50 to r = 0.63), but not for reports obtained from non-smoking mothers. CONCLUSIONS: Memory-based parental reports of short-term ETS exposure can play an important role in quantifying ETS exposure in infants and children.     

The effect of a novel smoking system--Accord--on ongoing smoking and toxin exposure.

Multiple potentially reduced exposure products (PREPs) are being introduced to the market, yet little is known about how they will be used and what their public health impact might be. To determine the impact of one such PREP--Accord--on ongoing smoking and toxin exposure, 11 smokers of light cigarettes were required to use increasing amounts of Accord (5, 10, and 15 per day) with the option of using their traditional cigarettes. Accord suppressed ongoing cigarettes per day and carbon monoxide (CO), but not cotinine, in a dose-dependent manner. Smoking 15 Accord per day decreased the number of traditional cigarettes smoked by 32% (-8.6 cigarettes per day) and CO levels by 27% (-5.9 ppm). However, Accord did not function as a perfect (i.e., one to one) substitute for cigarettes because the total number of nicotine products (Accord plus usual brand) per day increased by 24%. Participants believed that Accord was safer than traditional cigarettes but rated Accord as ineffective at suppressing cravings for cigarettes. These findings suggest that use of Accord results in significant decreases in cigarettes smoked and CO exposure. Whether these reductions will translate into health benefits or endure beyond 2 weeks is unknown. Because most PREPs will probably be used along with traditional cigarettes, their net health impact is a function of not only their toxicological profile but also their effect on ongoing smoking.     

Secondhand smoke exposure in Mexican discotheques.

This study describes the impact of exposure to secondhand smoke for subjects who spend time in a discotheque, by comparing within-subject baseline and postexposure urinary cotinine levels. A total of 100 nonsmoking volunteers from a central region of Mexico provided a urine sample before entering a discotheque and another sample an average of 6 hr after the end of exposure. Concentrations of cotinine and its metabolite, trans-3'-hydroxycotinine, were measured in the urine by liquid chromatography-mass spectrometry. In females the average preexposure level of urinary cotinine was 2.2 ng/ml, and the average postexposure level was significantly higher, at 15.7 ng/ml. In males the average preexposure level of cotinine was 3.7 ng/ml, compared with 49.1 ng/ml in the postexposure assessment. The highest postexposure values were found in men younger than 22 years old with a value of 469.5 ng/ml. Exposure to secondhand smoke is a serious health risk. Our findings are important given that many of our subjects were exposed to substantial amounts of secondhand smoke in discotheques, as evidenced by the high urinary cotinine and 3'-hydroxycotinine concentrations. These findings support the need to prohibit smoking in discotheques to protect nonsmokers' health.     

The dog as a passive smoker: effects of exposure to environmental cigarette smoke on domestic dogs.

Of the few studies available regarding the effects of smoking on animals, most of them involve animals actively smoking through the use of a mask or tracheostomy. The present study investigated the effects of passive smoke exposure on domestic dogs. The sample comprised 30 Yorkshire terriers (18 males) ranging in age from 27 to 106 months (M = 38.6+/-15.8) and weighing 1.9-4.0 kg (M = 3.04+/-0.48). Half of the dogs came from homes where residents smoked at least 20 cigarettes/day for a minimum of 24 months, and the other half were from homes without smokers. All animals were subjected to bronchoalveolar lavage to determine cell populations and the presence of anthracosis in macrophage cytoplasm; in addition, a carinal biopsy was obtained. To characterize environmental cigarette smoke exposure, urinary cotinine was determined by an immunochromatographic assay. Cotinine was not detected in the urine of dogs not exposed to cigarette smoke, whereas exposed dogs tested positive. In dogs exposed to cigarette smoke, macrophage and lymphocyte populations were significantly increased (p<.05) and anthracosis was present in the cytoplasm of macrophages. The measurement of urinary cotinine by an immunochromatographic assay is an effective method that can be used to confirm environmental tobacco exposure. Cytological analysis of bronchoalveolar lavage fluid demonstrated airway alterations triggered by passive exposure to tobacco smoke in domestic animals.     

Tobacco specific nitrosamines and potential reduced exposure products for smokers: a preliminary evaluation of Advance

Objective: To develop a method for evaluating the carcinogen delivery of potential reduced exposure products (PREPs) like Advance^TM, a PREP marketed to reduce smokers' exposure to one tobacco specific nitrosamine (TSN), NNK, a potent lung carcinogen.

Design, setting, and participants: Latin square ordered, three condition, outpatient, crossover design with 12 smokers of light or ultra-light cigarettes (15 or more cigarettes/day). In each five day condition, participants either smoked own brand, Advance^TM, or no cigarettes. Also, on the first and last day of each condition, participants smoked one cigarette in the laboratory.

Main outcome measures: Subject rated measures of tobacco/nicotine withdrawal, expired air carbon monoxide, urine concentrations of cotinine and NNAL (one TSN biomarker), puff volume, duration, number, and interpuff interval.

Results: Relative to own brand, Advance^TM produced similar withdrawal suppression, slightly lower carbon monoxide, equivalent cotinine, and 51% lower NNAL concentrations. The lowest cotinine and NNAL concentrations were observed in the no cigarette condition. Participants took fewer puffs when smoking Advance^TM.

Conclusions: Past experience with PREPs that failed to reduce smoking's harm demonstrates the need for clinical methods in PREP evaluation. This study shows how assessing PREP induced changes in withdrawal and exposure to carbon monoxide, nicotine, and carcinogens may help predict PREP harm reduction potential. Adequate withdrawal suppression, slightly lower concentrations of carbon monoxide, and reduction of one TSN biomarker were observed for Advance^TM. In the future, clinical methods like those described here may be valuable for evaluating PREPs before they are marketed publicly.

     

Effects of short-term nicotine deprivation on decision-making: delay, uncertainty and effort discounting.

Experimental evidence suggests that when opioid-dependent drug users are deprived of heroin, they become more likely to behave impulsively on a computer task. The current study examined whether nicotine deprivation has similar effects in cigarette smokers, causing an increase in impulsive decision-making. Simultaneously, the impact of deprivation on several other related decision-making tasks was assessed. Eleven smokers (> or = 15 cigarettes/day) participated in two experimental sessions. For one session, they smoked as usual until the session began. For the other, participants did not smoke for 24 hr. Abstinence was verified using levels of breath carbon monoxide and urinary cotinine. During each session, they completed computer tasks that assessed impulsivity by measuring the tendency to choose small, immediate rewards (cigarettes or money) over US dollar 10 available following a delay, as well as tasks in which smokers chose between small, certain, easily obtained rewards and US dollar 10 whose availability was uncertain or required high levels of effort to obtain. Deprivation increased preference for immediate cigarettes over delayed money, but did not alter preference for immediate money over delayed money. These findings indicate that short-term nicotine abstinence does increase impulsive decision-making, but only when the impulsive choice is drug-related. Increases were not related to a general increase in the value of immediate rewards per se or a general increase in aversion to delayed rewards. Decision-making in the other tasks followed a similar pattern: Deprivation increased preference for the cigarette alternative but did not alter the decision-making processes for nondrug rewards.     

Validity of self reports in a cohort of Swedish adolescent smokers and smokeless tobacco (snus) users

Objective: To validate self reports of cigarette and smokeless tobacco (snus) use in a prospective cohort of adolescents. Design: A cross sectional analysis of a cohort sub-sample. Setting: County of Stockholm, Sweden. Subjects: 520 adolescents in the final grade of junior high school (mean age 15.0 years). Main outcome measure: Concordance between self reported tobacco use and saliva cotinine concentration. Results: Using a cut point of 5 ng/ml saliva cotinine to discriminate active tobacco use, there was a 98% concordance between self reported non-use in the past month and cotinine concentration. The sensitivity of the questionnaire compared to the saliva cotinine test, used as the gold standard, was 90% and the specificity 93%. One hundred and fifteen out of 520 subjects (22%) reported monthly tobacco use. Among these, 67% (46/69) of the exclusive cigarette smokers, 82% (23/28) of exclusive snus users, and 94% (15/16) of mixed users (cigarettes + snus) had cotinine concentrations above 5 ng/ml. Among subjects reporting daily use 96% (64/67) had saliva cotinine concentrations above the cut point. Exclusive current cigarette users were more likely to be classified discordantly by questionnaire and cotinine test compared to snus users (odds ratio 3.2, 95% confidence interval 1.2 to 8.6). Conclusion: This study confirms the reliability of adolescents'' self reported tobacco use. In a context of low exposure to environmental tobacco smoke a cut off for saliva cotinine of 5 ng/ml reliably discriminated tobacco users from non-users. Irregular use of tobacco in this age group probably explains the discrepancy between self reported use and cotinine concentrations.