Michael Chaiton

A systematic review of longitudinal studies on the association between depression and smoking in adolescents

BackgroundIt is well-established that smoking and depression are associated in adolescents, but the temporal ordering of the association is subject to debate.MethodsLongitudinal studies in English language which reported the onset of smoking on depression in non clinical populations (age 13-19) published between January 1990 and July 2008 were selected from PubMed, OVID, and PsychInfo databases. Study characteristics were extracted. Meta-analytic pooling procedures with random effects were used.ResultsFifteen studies were retained for analysis. The pooled estimate for smoking predicting depression in 6 studies was 1.73 (95% CI: 1.32, 2.40; p < 0.001). The pooled estimate for depression predicting smoking in 12 studies was 1.41 (95% CI: 1.21, 1.63; p < 0.001). Studies that used clinical measures of depression were more likely to report a bidirectional effect, with a stronger effect of depression predicting smoking.ConclusionEvidence from longitudinal studies suggests that the association between smoking and depression is bidirectional. To better estimate these effects, future research should consider the potential utility of: (a) shorter intervals between surveys with longer follow-up time, (b) more accurate measurement of depression, and (c) adequate control of confounding.

Estimating the number of quit attempts it takes to quit smoking successfully in a longitudinal cohort of smokers.

Objectives The number of quit attempts it takes a smoker to quit successfully is a commonly reported figure among smoking cessation programmes, but previous estimates have been based on lifetime recall in cross-sectional samples of successful quitters only. The purpose of this study is to improve the estimate of number of quit attempts prior to quitting successfully. Design We used data from 1277 participants who had made an attempt to quit smoking in the Ontario Tobacco Survey, a longitudinal survey of smokers followed every 6 months for up to 3 years beginning in 2005. We calculated the number of quit attempts prior to quitting successfully under four different sets of assumptions. Our expected best set of assumptions incorporated a life table approach accounting for the declining success rates for subsequent observed quit attempts in the cohort. Results The estimated average number of quit attempts expected before quitting successfully ranged from 6.1 under the assumptions consistent with prior research, 19.6 using a constant rate approach, 29.6 using the method with the expected lowest bias, to 142 using an approach including previous recall history. Conclusions Previous estimates of number of quit attempts required to quit may be underestimating the average number of attempts as these estimates excluded smokers who have greater difficulty quitting and relied on lifetime recall of number of attempts. Understanding that for many smokers it may take 30 or more quit attempts before being successful may assist with clinical expectations.

Linking depression symptom trajectories in adolescence to physical activity and team sports participation in young adults

OBJECTIVE The objective of this study is to examine depressive symptom trajectories during adolescence as predictors of physical activity (PA) in young adulthood. METHODS Adolescents residing in Montreal, Canada (n=860) reported their depressive symptoms every 3-4 months during high school in 20 data collections. Three years later, participants reported engaging in moderate and vigorous intensity PA and team sports participation. Trajectories of depressive symptoms were estimated using latent growth modeling and examined as predictors of PA outcomes. RESULTS Three depression symptom trajectory groups were identified during adolescence: low and declining depressive symptom scores (group 1; 37.8%); moderate and stable depressive symptom scores (group 2; 41.6%); and high increasing depressive symptom scores (group 3; 20.6%). In multivariable analyses, group 2 and group 3 participated in less moderate-intensity PA and were less likely to participate in team sports compared to group 1. CONCLUSIONS The importance of examining intensity and type of PA as outcomes of depressive symptoms is highlighted. Targeted approaches are needed to encourage adolescents with moderate to high depression symptoms to engage in PA and team sports to improve their health and well-being.

Population Health and the Hardcore Smoker: Geoffrey Rose Revisited

The “hardening hypothesis” suggests that as smoking prevalence decreases, lighter smokers will quit first, leaving more “hardcore” smokers in the population. At a population level, however, the weight of evidence suggests that no hardening is occurring. By understanding the lessons from Geoffrey Roses model of population-level risk factor change, we argue that the hardening of the smoking population is not inevitable. The Rose model predicts that the effect of policy interventions, and changes in social norms, can shift the population-level risk distribution for continuing to be a smoker, making it more likely that all smokers will quit. This analysis also suggests that further reductions in smoking prevalence will not come without further changes in the underlying – and largely cultural – root causes of smoking in a population.

The association between past and current physical activity and depressive symptoms in young adults: a 10-year prospective study.

PURPOSE The objectives of this study were to assess (1) the longitudinal associations of past moderate-to-vigorous physical activity (MVPA) and involvement in team sports during secondary school with depressive symptoms in early adulthood, and (2) the cross-sectional associations of current MVPA and involvement in team sports with depressive symptoms during young adulthood. METHODS Data were drawn from the Nicotine Dependence in Teens study, which is an ongoing prospective cohort study of 1293 adolescents aged 12-13 years at baseline (52% female). Data analyses involved latent growth curve modeling and multiple hierarchical linear regression models. RESULTS Current MVPA (β = -0.12), but not past MVPA, participation was significantly negatively related to depressive symptoms during young adulthood (P < .05). Both current and past involvement in team sports were significantly negatively related to depressive symptoms (β ≥ -0.09; P < .05); however, these associations were no longer significant (P = .08) when covariates were controlled for. CONCLUSIONS Findings provide insight about the unique associations between the timing and type of physical activity and depressive symptoms, suggesting that physical activity within team sport contexts should be encouraged so that young adults may experience less depressive symptoms.

Use of cigarettes to improve affect and depressive symptoms in a longitudinal study of adolescents

Smoking to alleviate negative affect or improve physiological functioning (i.e., self-medication) is one explanation for the association between depression and smoking in adolescents. This study tests whether using cigarettes to improve mood or physiological functioning is associated with the onset, and change over time, of elevated depressive symptoms. Data were drawn from the Nicotine Dependence in Teens study which followed 1293 participants initially aged 12-13 years in Montreal, Canada every three months for five years. The subsample included 662 adolescents who had been current smokers (reported smoking during the previous three months) at any point during the study. Survival analysis was used to test whether self-medication scores predicted onset of elevated depressive symptoms. Changes over time in depressive symptom scores relative to self-medication scores were modeled in growth curve analyses controlling for sex and number of cigarettes smoked per week. Smokers who reported higher self-medication scores had higher depressive symptom scores. The interaction between self-medication scores and the acceleration rate in depressive symptom scores was significant and negative, suggesting that participants with higher self-medication scores had decelerated rates of change in depression over time compared to participants with lower self-medication scores. Smoking appears to be ineffective at reducing depressive symptoms. These findings are consistent with a version of the Positive Resource Model that suggests that smoking will not lower depressive symptoms, but could slow the rate of change over time. Alternatively, the perceived positive benefits may be the result of alleviation of symptoms of withdrawal and craving resulting from abstinence. The self-medication scale may identify a population at risk of increased levels of depressive symptoms.

Cohort Profile: The Nicotine Dependence in Teens (NDIT) Study

The Nicotine Dependence in Teens (NDIT) study is a prospective cohort investigation of 1294 students recruited in 1999-2000 from all grade 7 classes in a convenience sample of 10 high schools in Montreal, Canada. Its primary objectives were to study the natural course and determinants of cigarette smoking and nicotine dependence in novice smokers. The main source of data was self-report questionnaires administered in class at school every 3 months from grade 7 to grade 11 (1999-2005), for a total of 20 survey cycles during high school education. Questionnaires were also completed after graduation from high school in 2007-08 and 2011-12 (survey cycles 21 and 22, respectively) when participants were aged 20 and 24 years on average, respectively. In addition to its primary objectives, NDIT has embedded studies on obesity, blood pressure, physical activity, team sports, sedentary behaviour, diet, genetics, alcohol use, use of illicit drugs, second-hand smoke, gambling, sleep and mental health. Results to date are described in 58 publications, 20 manuscripts in preparation, 13 MSc and PhD theses and 111 conference presentations. Access to NDIT data is open to university-appointed or affiliated investigators and to masters, doctoral and postdoctoral students, through their primary supervisor (www.nditstudy.ca).

Early predictors of suicidal ideation in young adults.

Objective: To identify early predictors of suicidal ideation in young adults, and to determine when specific time-varying determinants become important in predicting later suicidal ideation. Methods: Data were available for 877 participants in the Nicotine Dependence in Teens study, an ongoing prospective cohort of students aged 12 to 13 years at cohort inception in 1999. Time-invariant covariates included age, sex, mothers education, language, and self-esteem. Time-varying covariates included depression symptoms, family stress, other stress, alcohol use, cigarette use, and team sports. Independent predictors of past-year suicidal ideation at age 20 years were identified in 5 multivariable logistic regression analyses, one for each of grades 7, 8, 9, 10, and 11. Results: Eight per cent of participants (mean age 20.4 years [SD 0.7]; 46% male) reported suicidal ideation in the past year. In grade 7, none of the potential predictor variables were statistically significantly associated with suicidal ideation. In grade 8, participation in sports teams in and (or) outside of school protected against suicidal ideation (OR 0.6; 95% CI 0.4 to 0.8; P = 0.002). Depression symptoms in grades 9, 10, and 11 were independent predictors of suicidal ideation (OR 2.2; 95% CI 1.5 to 3.2, OR 1.6; 95% CI 1.0 to 2.5, and OR 1.9; 95% CI 1.1 to 3.4, respectively). No other variables were statistically significant in the multivariate models. Conclusion: Depression symptoms as early as in grade 9 predict suicidal ideation in early adulthood. It is possible that early detection and treatment of depression symptoms are warranted as part of suicide prevention programs.

Transitions in Smoking Status Over Time in a Population-Based Panel Study of Smokers

Introduction: Few studies have examined the transitions of smokers in the general population through multiple periods of daily, occasional smoking, or abstinence over time. Transitions from daily to occasional smoking are particularly of interest as these may be steps toward cessation. Methods: The Ontario Tobacco Survey panel study followed 4,355 baseline smokers, semiannually for up to 3 years. Probabilities of all possible changes in smoking status more than 6 months were estimated using 13,000 repeated measures observations generated from sets of 3 consecutive interviews (n = 9,932 daily smokers, 1,245 occasion smokers, and 1,823 abstinent for at least 30 days, at Time 1). Results: For initial daily smokers, an estimated 83% remained daily smokers more than 2 follow-ups. The majority of those who had been abstinent for 30 days at 1 interview, were also former smokers at the following interview. In contrast, occasional smoking status was unstable and future smoking status was dependent upon smoking history and subjective dependence. Among daily smokers who became occasional smokers 6 months later, an estimated 20% became a former smoker, at the next interview, but 50% returned to daily smoking. Daily, turned occasional smokers who rebounded back to daily smoking were more likely to describe themselves as addicted at Time 1. Continuing occasional smokers were somewhat less likely to intend to quit, or have tried, despite considering themselves less addicted. Conclusions: Reducing to occasional smoking can be a stepping stone toward cessation but entails a greater risk of return to daily smoking, compared with complete abstinence.

Symptoms of depression are longitudinally associated with sedentary behaviors among young men but not among young women.

OBJECTIVE A habitual sedentary lifestyle is associated with adverse health outcomes; however, the predictors of sedentary behaviors have not been sufficiently explored to inform the development and delivery of effective interventions to reduce sedentary behaviors. This study examined whether reports of symptoms of depression could predict weekly time spent in sedentary behaviors (i.e., television watching, computer use) 4years later. METHOD Self-reported symptoms of depression were assessed at age 20years (2007-08), and television watching time and computer use were assessed at age 24years (2011-12) in 761 adults (45% men) participating in the Nicotine Dependence in Teens study. Data were analyzed using linear regression analysis, with separate models for men and women. RESULTS After controlling for past sedentary behavior, symptoms of depression at age 20years predicted more computer use 4years later in men (R(2)=.21, β=.13, p<.05), but not in women. Symptoms of depression did not predict television watching. CONCLUSIONS Results highlight the need to distinguish between types of sedentary behaviors as their predictors may differ. Further, they provide support for the hypothesis that psychological factors, in this case symptoms of depression, may relate to select sedentary behaviors in young men.