***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: BACKGROUND Epidemiologic studies have reported an association between major depression and smoking . This prospect i ve study examines the role of depression in smoking progression and cessation , and the role of smoking in first-onset major depression . METHODS Data are from a 5-year longitudinal epidemiologic study of 1007 young adults . Incidence and odds ratios ( ORs ) are based on the prospect i ve data . Hazards ratios are based on the combined lifetime data and estimated in Cox proportional hazards models with time-dependent covariates . RESULTS Based on the prospect i ve data , history of major depression at baseline increased significantly the risk for progression to daily smoking ( OR , 3.0 ; 95 % confidence interval , 1.1 - 8.2 ) , but did not decrease significantly smokers ' rate of quitting ( OR , 0.8 ; 95 % confidence interval , 0.4 - 1.6 ) . History of daily smoking at baseline increased significantly the risk for major depression ( OR , 1.9 ; 95 % confidence interval , 1.1 - 3.4 ) . These estimates were reduced somewhat when history of early ( ie , before age 15 years ) conduct problems was controlled . Estimates based on lifetime data were consistent with these results . CONCLUSIONS The observed influences from major depression to subsequent daily smoking and smoking to major depression support the plausibility of shared etiologies . Separate causal mechanisms in each direction might also operate , including self-medication of depressed mood as a factor in smoking progression and neuropharmacologic effects of nicotine and other smoke substances on neurotransmitter systems linked to depression Objective : Previous research has indicated an association between smoking and  depression in adolescents , although the nature of the relationship is controversial . We sought to underst and this relationship better in a prospect i ve study by investigating whether there are sub population s of adolescents with different relationships between smoking and depressive symptoms . Methods : Our sample was 925 adolescents attending one of five Northern Virginia high schools , grade s 9 to 12 . We used General Growth Mixture Modeling as our method because it allowed identification and characterization of depressive symptoms trajectories and assessment of the effects of trajectory on 12th grade smoking . We defined the binary variable 12th grade current smoking as smoking on 1 or more of the past 30 days and more than 100 cigarettes smoked in a lifetime , versus not having smoked in the past 30 days . Results : We identified three trajectories : high , medium , and low depressive symptoms . For adolescents with high symptoms , 9th grade ( baseline ) smoking was associated with an overall deceleration of depressive symptoms , whereas for adolescents with moderate symptoms , baseline smoking was associated with an overall acceleration in depressive symptoms . Baseline smoking was not associated with rate of change in depressive symptoms for adolescents with low symptoms , nor was it associated with baseline depressive symptoms in any trajectory . Conclusion : These findings demonstrate that there is a relationship between smoking and depressive symptoms in adolescents , and that the relationship can vary by developmental trajectory , suggesting etiological heterogeneity . GGMM = General Growth Mixture Modeling ; CES-D = Center for Epidemiological Studies Depression ; GMM = Growth Mixture Modeling ; BIC = Bayesian Information Criterion ; LMR LRT = Lo-Mendell-Rubin Likelihood Ratio ; OR = odds ratio ; CI = confidence interval Although it has been hypothesized that depressive persons have an excess risk of cancer , few prospect i ve data are available . The association between depressiveness and subsequent incidence of lung cancer was studied in the nationally representative Mini-Finl and Health Survey . The study population comprised 7,018 adult men and women , free from cancer at the baseline , carried out in 1978 - 1980 . During a 14-year follow-up , 605 cancer cases occurred , of which 70 were male lung cancer patients .  Mental problems and disorders were assessed at the baseline examination using st and ard interview techniques ( General Health Question naire and Present State Examination ) . The relative risk of lung cancer between depressive persons and individuals with a normal depressiveness score was 3.32 ( 95 % confidence interval 1.53 - 7.20 ) . Neither adjustment for the potential confounding factors of age , education , geographic area , smoking , alcohol consumption , body mass index , serum cholesterol , leisure-time exercise , general health , and use of antidepressant medication nor exclusion of cancer cases occurring during the first 4 years of follow-up notably altered the results . There was a strong interaction between depressiveness and smoking . The relative risks of lung cancer between smokers and nonsmokers were 3.38 ( 95 % confidence interval 1.09 - 10.52 ) at normal depressiveness score levels and 19.67 ( 95 % confidence interval 2.57 - 150.7 ) at strongly elevated levels , respectively . It is possible that depressiveness modifies the effect of smoking on lung cancer risk either by biologic mechanisms or by affecting smoking behavior Smokers have a higher prevalence of major depressive episodes and depressive symptoms than the general population , but whether this association is causal , or is due to confounding or reverse causation is uncertain because of the problems inherent in some epidemiological studies . Mendelian r and omization , in which a genetic variant is used as a surrogate for measuring exposure , is an approach which may be used to better underst and this association . We investigated the rs1051730 single nucleotide polymorphism in the nicotine acetylcholine receptor gene cluster ( CHRNA5-CHRNA3-CHRNB4 ) , associated with smoking phenotypes , to determine whether women who continued to smoke were also more likely to report a low mood during pregnancy . We found among women who smoked pre-pregnancy , those with the 1051730 T allele smoked more and were less likely to quit smoking during pregnancy , but were also less likely to report high levels of depressed mood at 18 weeks of pregnancy ( per allele OR = 0.84 , 95%CI 0.72 to 0.99 , p = 0.034 ) . The association between genotype and depressed mood was limited to women who were smokers prior to pregnancy , with weak evidence of an interaction between smoking status and genotype ( p = 0.07 ) . Our results do not support a causal role of smoking on depressed mood , but are consistent with a self-medication hypothesis , whereby smoking is used to alleviate symptoms of depression . A replication study using multiple genetic variants which influence smoking via different pathways is required to confirm these findings and provide evidence that the genetic variant is reflecting the effect of quitting smoking on depressed mood , and is not directly affecting mood INTRODUCTION Smoking research and intervention efforts have neglected older women . Depressive symptoms , which are common in middle-aged and older women , are related to the maintenance of adult smoking . METHODS This study investigated the relation of a composite measure of current depressive symptoms , derived from a short form of the Center for Epidemiological Studies Depression Scale , and history of depressive symptoms , derived from two items from the Diagnostic Interview Schedule , to smoking outcomes in the Women 's Health Initiative Observational Study ( N = 90,627 ) . Participants were postmenopausal with an average age of 63.6 years at baseline . Participants were recruited from urban , suburban , and rural areas surrounding 40 clinical centers in the United States . Analyses controlled for age , educational level , and ethnicity . RESULTS In multinomial logistic regression analyses , depressive symptoms were related cross-sectionally to current light ( odds ratio [ OR ] = 1.19 , 95 % CI = 1.14 - 1.23 ) and heavier ( OR = 1.28 , 95 % CI = 1.23 - 1.32 ) smoking at baseline compared with nonsmokers . In prospect i ve multiple logistic regression analyses , baseline depressive symptoms were negatively predictive of smoking cessation at a 1-year follow-up ( OR = .85 , 95 % CI = 0.77 - 0.93 ) and at participants ' final assessment s in the study ( OR = .92 , 95 % CI = 0.85 - 0.98 ) . Light smokers had more than 2 times higher odds of smoking cessation than did heavier smokers . CONCLUSIONS The present findings demonstrate a consistent link between depressive symptoms and negative smoking-related behaviors among middle-aged and older women at both light and heavier smoking levels Using data from a 4-wave longitudinal study with a school-based sample of 1,218 middle adolescents , the authors investigated the directionality ( e.g. , unidirectionality and bidirectionality ) of the prospect i ve relationship between depressive symptoms and cigarette use within the context of potential confounding variables and common and unique intrapersonal and interpersonal predictors . Findings indicated that serious and persistent depressive symptoms were prospect i ve predictors of increased cigarette use across time , after controlling for baseline levels of smoking . Similarly , heavy and persistent smoking prospect ively predicted increases in depressive symptoms . Intrapersonal and interpersonal predictors of cross-temporal changes in depressive symptoms and cigarette use were more unique than common . Latent growth curve modeling indicated a quadratic trend in adolescent cigarette smoking across time with an initial acceleration followed by a deceleration , though there was substantial intraindividual variation in individual trajectories OBJECTIVE This study aim ed to develop a simple risk table of modifiable factors prospect ively associated with  depression in later life that could be used to guide the assessment , management and introduction of preventive strategies in clinical practice . METHODS This retrospective cohort study included 4636 men aged 65 to 83 years living in the community who denied history of past diagnosis or treatment for depression . They self-reported information about their physical activity , weight and height , smoking history , alcohol consumption and dietary habits , as well as history of hypertension , diabetes , coronary heart disease and stroke . We calculated the body mass index ( BMI ) in kg/m(2 ) . Three to 8 years later they were assessed with the Geriatric Depression Scale 15 ( GDS-15 ) and those with a total score of 7 or greater were considered to display clinical ly significant symptoms of depression . We used binomial exponentiated log-linked general linear models to estimate the risk ratio ( RR ) and 95 % confidence interval ( 95 % CI ) of incident depression after adjusting for age , education , marital status and prevalent medical illnesses . We calculated the probability of depression for each individual combination of risk factors and displayed the results in a risk table . RESULTS Two hundred and twenty-nine men ( 4.5 % ) showed evidence of incident depression 5.7±0.9 ( mean±st and ard deviation ) years later . Measured dietary factors showed no association with incident depression . The probability of depression was the highest for older men who were underweight , overweight or obese , physically inactive , risk drinkers and smokers ( 12.0 % , 95 % CI=7.0 % , 17.1 % ) , and the lowest for those who had all 4 healthy lifestyle markers : physically active , normal body mass , non-risk drinking and non-smoking ( 1.6 % , 95 % CI=0.6 % , 2.5 % ) . The probability of incident depression fell between these two extremes for different combinations of lifestyle practice s. CONCLUSION Four modifiable lifestyle factors can be used in combination to produce a risk table that predicts the probability of incident depression over a period of 3 to 8 years . The risk table is simple , informative and can be easily incorporated into clinical practice to guide assessment and risk reduction interventions BACKGROUND The aim of the present study was to investigate the stability and longitudinal association between depression and smoking status within a community sample with type 2 diabetes ( T2D ) while controlling for sociodemographic and disease-related variables . METHODS Adults with T2D were recruited and agreed to be followed-up via r and om digit dialing for the Montreal Diabetes Health Study . At baseline , 1614 individuals were classified as never ( n = 592 ) , former ( n = 690 ) , light ( ≤10 cigarettes a day ; n = 128 ) and moderate-heavy ( 11 + cigarettes a day ; n = 204 ) smokers . Depression was assessed using the Patient Health Question naire-9 and individuals were classified as either " none " or having depression syndrome . Generalized estimating equations were used to test the association between depression syndrome and current smoking status while controlling for other demographic and health-related variables . RESULTS Prevalence rates of smoking and depression showed mild to substantial agreement over time . Depression syndrome was significantly associated with moderate-heavy smoking in the fully adjusted model using cross-sectional ( all four waves ; odds ratio [ OR ] 1.46 ; 95 % confidence interval [ CI ] 1.08 - 1.99 ; P < 0.05 ) and longitudinal ( controlling for depression at baseline ; OR 1.54 ; 95 % CI 1.02 - 2.31 ; P < 0.05 ) data . CONCLUSIONS Smoking and depression prevalence rates appear to be stable over time in our community sample with T2D . Moderate-heavy smoking is strongly associated with elevated depression , both in cross-sectional and longitudinal models . Persistent moderate-heavy smokers may be at increased risk of both physical and mental health complications . This burden is even greater for those with T2D Both 
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Overall , nearly half the studies reported that baseline depression/anxiety was associated with some type of later smoking behavior , while over a third found evidence that a smoking exposure was associated with later depression/anxiety .
The results varied considerably , with evidence for smoking both associated with subsequent depression and anxiety , and vice versa .
Suggesting that despite advantages of longitudinal studies , they can not alone provide strong evidence of causality .