***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Adolescent cigarette smokers from r and omly selected classrooms from 24 California and Illinois high schools were assessed regarding their interest in cessation , reasons for quitting , and smoking temptation circumstances .  These data were analyzed by gender . Males and females were not found to differ in quit stage or perceived likelihood of ever quitting smoking , although males reported being somewhat more likely to have ever tried to quit in the past . The associations of reasons for quitting were not found to vary by gender in most comparisons . On the other h and , the associations of smoking temptation circumstances with gender showed that a greater percentage of females than males reported more circumstances that would make them tempted to smoke . Smoking cigarettes to regulate one 's affective states , and to avoid nicotine withdrawal , may be functions of smoking that impede efforts at quitting , particularly among adolescent females OBJECTIVE To examine the prevalence and persistence of cigarette smoking along with health outcomes in a clinical sample of substance-abusing adolescents . DESIGN This is a 2-year prospect i ve case series study . SETTING Subjects were recruited from two private , hospital-based inpatient adolescent substance abuse treatment facilities . PARTICIPANTS A consecutive sample of 166 adolescents , ages 12 to 18 , meeting Diagnostic and Statistical Manual of Mental Disorders ( 3rd ed , revised ) criteria for substance abuse participated in the present investigation . Of the original sample , 154 and 144 were interviewed 12 and 24 months after discharge , respectively . MEASUREMENT AND RESULTS Information regarding cigarette smoking , drug and alcohol use , and respiratory problems was based on self-report by the adolescents and was corroborated by parent interview . The prevalence of smoking in this sample of teens immediately before treatment was 85 % . Sixty-one percent of the sample smoked 1/2 pack or more/day and 75 % were daily smokers . Although prevalence ( 74 and 77 % ) and average daily cigarette consumption ( 11.1 and 10.7 cigarettes daily ) decreased at 12 and 24 months after treatment , rates remained very high . Teens reporting posttreatment respiratory problems smoked more , and heavier smokers at the time of treatment were more likely to report respiratory problems at follow-up than lighter smokers . CONCLUSIONS Substance-abusing teens  smoke at rates far and above those of the general adolescent population . Further , these teens appear at increased risk for negative health consequences regardless of posttreatment drug and alcohol use . These findings highlight the importance of preventing adolescent cigarette smoking by substance abuse treatment programs The Global Youth Tobacco Survey ( GYTS ) project was developed by the World Health Organization and the US Centers for Disease Control and Prevention to track tobacco use among youth in countries across the world , using a common methodology and core question naire . The GYTS is school based and employs a two-stage sample design to produce representative data on smoking among students aged 13 - 15 years . The first stage consists of a probabilistic selection of schools , and the second consists of a r and om selection of classes from the participating schools . All students in the selected classes are eligible for the survey . In 1999 , the GYTS was conducted in 13 countries and is currently in progress in over 30 countries . This report describes data from 12 countries : Barbados , China , Costa Rica , Fiji , Jordan , Pol and , the Russian Federation ( Moscow ) , South Africa , Sri Lanka , Ukraine ( Kiev ) , Venezuela , and Zimbabwe . The findings show that tobacco use in the surveyed age group ranged from a high of 33 % to a low of 10 % . While the majority of current smokers wanted to stop smoking , very few were able to attend a cessation programme . In most countries the majority of young people reported seeing advertisements for cigarettes in media outlets , but anti-tobacco advertising was rare . The majority of young people reported being taught in school about the dangers of smoking . Environmental tobacco smoke exposure was very high in all countries . These results show that the GYTS surveillance system is enhancing the capacity of countries to design , implement , and evaluate tobacco prevention and control programmes Objective : To describe short term patterns of smoking acquisition exhibited by adolescent smokers . Design : Interview records from the prospect i ve development and assessment of nicotine dependence in youth study were examined retrospectively . Interviews were conducted three times per year over 30 months . Subjects : 164 students in grade s 7–9 ( ages 12–15 years , 86 girls , 78 boys ) who had used cigarettes at least twice . Main outcome measures : A continuous timeline of smoking activity , beginning with the subject ’s first use of tobacco and continuing through follow up , was translated into six patterns — abstinent , sporadic , occasional , daily , escalating , and intermittent . Outcome measures were the proportion of subjects starting/ending in each pattern , and the number of transitions per subject between patterns . Results : There was a general but discontinuous progression from infrequent to more frequent use , with many interspersed periods of not smoking . Escalation to daily smoking was common after the development of dependence symptoms , but was rare among those who did not have symptoms . After the appearance of symptoms , both transitions to heavier daily smoking and attempts at cessation increased . Conclusions : Movement to heavier , more frequent smoking is generally unidirectional , although many youths attempt to quit one or more times . The appearance of any symptom of dependence altered the subsequent pattern of smoking behaviour . Future investigators might consider using more frequent data points and a continuous timeline to track smoking behaviour OBJECTIVE To examine factors associated with cessation of smoking in adolescents 12 to 18 years of age who smoke cigarettes . DESIGN AND SETTING Prospect i ve school-based cohort study of 1384 New Hampshire high school students surveyed at baseline and annually up to 3 subsequent years regarding their substance abuse behaviors , including adolescents who smoked 1 or more cigarettes within the past 30 days at baseline . OUTCOME MEASURES Cessation behavior was defined by a subsequent response indicating nonsmoking status . We examined associations between smoking cessation and baseline measurements of the level of addiction ( cigarette consumption pattern ) , experience with quitting , intent to quit now and in the future , opinion of adults smoking more than 1 pack of cigarettes per day , social influences to smoke , sex , and psychological attributes . RESULTS Of 276 adolescents who qualified as cigarette smokers at baseline , 123 ( 44.6 % ) were occasional smokers , 65 ( 23.6 % ) were daily smokers of 1 to 9 cigarettes , and 88 ( 31.9 % ) were daily smokers of 10 or more cigarettes . While 39 ( 14.1 % ) had smoked for 1 year or less , 62 ( 22.5 % ) had smoked for 6 or more years . Seventy-five ( 27.2 % ) reported failed past attempts to quit smoking , 71 ( 25.7 % ) reported wanting to quit now , and 50 ( 18.1 % ) reported definitely intending to be a nonsmoker in the future . Seventy-nine smokers ( 28.6 % ) described themselves as nonsmokers in follow-up surveys . The smoking cessation rate was 46.3 % among occasional smokers , 12.3 % among daily smokers of 1 to 9 cigarettes , and 6.8 % among daily smokers of 10 or more cigarettes . Smoking cessation was associated with occasional smoking status ( adjusted odds ratio 6.67 compared with daily smokers of 10 or more cigarettes [ 95 % confidence intervals , 2.26 - 19.69 ] ) , and definite intentions to quit in the future ( 2.67 [ 95 % confidence intervals , 1.2 - 5.7 ] ) . Most of those with definite intentions to quit in the future were occasional smokers ( 92.0 % ) . CONCLUSIONS This study documents cessation of smoking in nearly one third of the adolescent smokers . The cessation rate among daily smokers of 10 or more cigarettes per day is comparable with adult cessation rates . Adolescents who are less addicted , measured by low frequency of cigarette use , are more likely than daily users to quit . In addition , definite intent to quit in the future predicts cessation , but only among occasional smokers . In contrast with adults , experience with quitting was not associated with a higher likelihood of cessation . Pediatricians should focus on keeping occasional smokers from moving into daily smoking status , where nicotine addiction begins to play a prominent role in maintaining the behavior . Further study is needed to guide enhancement of the recruitment of adolescents into cessation , assessment of nicotine dependence in daily adolescent smokers , and appropriate use of nicotine replacement therapy in this group Seven thous and one hundred twenty-four members of the Classes of 1985 and 1986 who had participated as seventh grade rs in one of several smoking prevention programs  were tracked and surveyed for smoking habits at 5- and 6-year follow-up : participation exceeded 90 % in both cohorts . These data indicated that participants who received seventh- grade interventions based on the social influences model had similar smoking patterns compared to participants in other conditions . This finding supports the call for booster sessions after the initial seventh- grade intervention program . Future follow-up studies will assess whether the earlier benefits associated with the social influences model will translate into measurable differences in adult smoking patterns This study compared two strategies for preventing cigarette smoking among high-school students . One strategy emphasized social-pressure resistance skills , while the other focused on education about health concerns which are relevant to high-school students . Additionally , the use of same-age peer leaders and the use of familiar models in media presentations were investigated . The results suggest that social-influences resistance training was efficacious in reducing transitions to higher use by those who had previously experimented with cigarettes . Health education was most effective in preventing initial experimentation among those who had not smoked prior to the beginning of the study . Neither program was effective in limiting transitions among those who had gone beyond the experimental stage of smoking , and neither had any effect on encouraging cessation . There were no differences which could be attributed to peer leaders or to familiar media models . During later adolescence , a combined health education and social skills training approach is advocated . It is suggested that while there are some gains by implementing programs during late adolescence , prevention programs targeted at younger students may be more effective generally BACKGROUND Although many sociodemographic and psychosocial factors have been identified as related to adolescent smoking , few studies have examined the role of nicotine-dependence ( ND ) symptoms . The objective was to study the association between ND symptoms and smoking status among adolescents in the early stages of the smoking onset process . METHODS The McGill University Study on the Natural History of Nicotine Dependence is an ongoing 6-year prospect i ve investigation of the natural history of ND among 1267 grade 7 students in ten Montreal high schools . The baseline response was 55.4 % . Subjects for this cross-sectional analysis of baseline data , collected in 1999 , included 241 past 3-month smokers ( mean age [SD]=13.0+/-0.7 years at baseline ) .  ND symptoms were measured in five indicators , including a measure based on the criteria for tobacco dependence in the International Classification of Diseases-10th Revision ( ICD-10 ) , the  Hooked  on  Nicotine  Checklist , and three symptom clusters ( withdrawal , self-medication , and ND/cravings symptoms ) . The association between ND symptom indicators and each of sporadic , monthly , weekly , and daily smoking relative to less frequent smoking was investigated in multiple logistic regression analysis . RESULTS Despite low cigarette exposure , 16.6 % ( 95 % confidence interval [ CI ] , 11.9%-21.3 % ) of past 3-month smokers were tobacco dependent . The proportion increased from 0 % , 3.1 % ( 95 % CI , 0.0%-9.2 % ) , and 4.6 % ( 95 % CI , 0.2%-9.0 % ) among triers , sporadic smokers , and monthly smokers , respectively , to 19.4 % ( 95 % CI , 5.5%-33.3 % ) and 65.9 % ( 95 % CI , 51.9%-79.9 % ) among weekly and daily smokers , respectively . ND/cravings consistently distinguished each smoking category from less frequent smokers ; the odds ratios ( 95 % CI ) for ND/cravings symptoms were 1.16 ( 0.99 - 1.35 ) in sporadic smokers ; 1.17 ( 1.06 - 1.29 ) in monthly smokers ; 1.34 ( 1.19 - 1.50 ) in weekly smokers ; and 1.39 ( 1.22 - 1.59 ) in daily smokers . CONCLUSIONS These data challenge current smoking onset models , which suggest that ND develops only after several years of heavy or daily smoking . ND symptoms are associated , at least cross-sectionally , with increased smoking in adolescents . To increase the likelihood of being effective , tobacco-control programs for children and adolescents will need to take early ND symptoms into account Objective . To test the long-term efficacy of brief counseling plus a computer-based tobacco intervention for teens being seen for routine medical care . Methods . Both smoking and nonsmoking teens , 14 to 17 years of 
    Output:
    
The high prevalence of cessation attempts and relapse among adolescent smokers extends to young adolescents and non-daily smokers .