Identifying trajectories of adolescent smoking: an application of latent growth mixture modeling

Tracking clusters of patients over time enables extracting information from medico-administrative databases

CONTEXT

Identifying clusters (i.e., subgroups) of patients from the analysis of medico-administrative databases is particularly important to better understand disease heterogeneity. However, these databases contain different types of longitudinal variables which are measured over different follow-up periods, generating truncated data. It is therefore fundamental to develop clustering approaches that can handle this type of data.

OBJECTIVE

We propose here cluster-tracking approaches to identify clusters of patients from truncated longitudinal data contained in medico-administrative databases.

MATERIAL AND METHODS

We first cluster patients at each age. We then track the identified clusters over ages to construct cluster-trajectories. We compared our novel approaches with three classical longitudinal clustering approaches by calculating the silhouette score. As a use-case, we analyzed antithrombotic drugs used from 2008 to 2018 contained in the Échantillon Généraliste des Bénéficiaires (EGB), a French national cohort.

RESULTS

Our cluster-tracking approaches allow us to identify several cluster-trajectories with clinical significance without any imputation of data. The comparison of the silhouette scores obtained with the different approaches highlights the better performances of the cluster-tracking approaches.

CONCLUSION

The cluster-tracking approaches are a novel and efficient alternative to identify patient clusters from medico-administrative databases by taking into account their specificities.

Developmental trajectories of tobacco use and risk factors from adolescence to emerging young adulthood: a population-based panel study

BACKGROUND

Adolescence to young adulthood is a critical developmental period that determines lifelong patterns of tobacco use. We examined the longitudinal trajectories of tobacco use, and risk factors for its use, and explored the association between the trajectories of mobile phone dependency and smoking throughout the life-course among adolescents and young adults.

METHODS

Data of 1,723 subjects (853 boys and 870 girls) were obtained from six waves of the Korean Children and Youth Panel Survey (mean age = 13.9-19.9 years). To identify trajectories of smoking and mobile phone dependency, group-based trajectory modelling (GBTM) was conducted. A multinomial logistic regression analysis was performed to identify the characteristics of the trajectory groups.

RESULTS

GBTM identified four distinct smoking trajectories: never smokers (69.1%), persistent light smokers (8.7%), early established smokers (12.0%), and late escalators (10.3%). Successful school adjustment decreased the risk of being an early established smoker (odds ratio [OR] 0.46, 95% confidence interval [CI] 0.27-0.78). The number of days not supervised by a guardian after school was positively associated with the risk of being an early established smoker (OR 1.96, 95% CI 1.23-3.13). Dependency on mobile phones throughout the life-course was positively associated with the risk of being a persistent light smoker (OR 4.04, 95% CI 1.32-12.34) or early established smoker (OR 8.18, 95% CI 4.04-16.56).

CONCLUSIONS

Based on the group-based modeling approach, we identified four distinctive smoking trajectories and highlight the long-term effects of mobile phone dependency, from early adolescence to young adulthood, on smoking patterns.

Social competence, leisure time activities, and smoking trajectories among adolescent boys: Data from The Korean Children & Youth Panel Survey

OBJECTIVES

The purpose of this study was to identify the trajectories and potential predictors of tobacco use during adolescence in Korea and to develop appropriate strategies for the implementation of tobacco use prevention programs.

METHODS

The trajectory of tobacco use and associated predictors were analyzed for 1,169 male students from grade 6 (age 11-12) to grade 10 (age 15-16) in the Korean Children & Youth Panel Survey from 2012 to 2016.

RESULTS

Three trajectories of smoking experience were identified: non-smokers (class 1: n=775, 82.3%), temporary users (class 2: n=32, 3.4%), and regular users (class 3: n=135, 14.3%). When compared to non-smokers, temporary users had a higher likelihood of living with a single parent, dissatisfaction with grades, having a girlfriend, having been victimized at least once, and having at least 1 delinquent friend in grade 7 (when smoking experimentation was at its peak). Significant factors associated with regular use included having a girlfriend, committing at least 1 type of delinquent behavior, and being a non-reader. Committing at least 1 type of delinquent behavior and having at least 1 delinquent friend were associated with regular users, distinguishing them from temporary users.

CONCLUSIONS

Understanding why adolescents exhibit different trajectories of tobacco use by identifying the factors associated with each trajectory can contribute to the development of tailored prevention strategies and early cessation programs for adolescents.

Developmental antecedents of young adults' solidarity during the Covid-19 pandemic: The role of sympathy, social trust, and peer exclusion from early to late adolescence

This study explored characteristics of young adults’ solidarity during the Covid‐19 pandemic by identifying three different profiles, characterized by low (23%), average (54%), and high solidarity (23%). Based on longitudinal Swiss panel data (N_T1 = 797, M_{age T1} = 12.15 years, 51% female; 28% migration background representing diverse ethnicities; N_T2 = 707, M_{age T2} = 15.33 years; N_T3 = 596, M_{age T3} = 18.31 years), the study combined person‐ and variable‐centered approaches to examine whether sympathy, social trust, and peer exclusion at earlier phases in development predicted membership in pandemic‐related solidarity profiles (N_T4 = 300, M_{age T4} = 20.33 years). All developmental predictors were significantly associated with the likelihood of expressing solidarity during the pandemic as young adults.

Self-rated health trajectories: A dynamic time warp analysis

Self-rated health (SRH), individuals’ overall perception of their health, is a key predictor of health events. To target disease prevention efforts, it is important to understand how SRH develops over time. The goal of this short communication is to find prototypic SRH trajectories by applying dynamic time warping, a time series comparison technique initially developed for speech recognition. Revealing prototypic SRH trajectories can help direct disease prevention efforts towards trajectories that are more likely to result in adverse health events. Based on data from a Dutch representative sample of 2,154 individuals, our dynamic time warp analysis suggests that Dutch individuals do not typically show a steady growth or decline in SRH. Instead, we identified four relatively stable SRH trajectories that differed in average SRH. One of these trajectories is a path of consistent low SRH.

Cigarette smoking trajectories in adolescent smokers: Does the time axis metric matter?

INTRODUCTION

Most studies modeling adolescent cigarette smoking trajectories use age as the time axis, possibly obscuring depiction of the natural course of cigarette smoking. We used a simulated example and real data to contrast smoking trajectories obtained from models that used time since smoking onset or calendar time (age) as the time axis.

METHODS

Data were drawn from a longitudinal investigation of 1293 grade 7 students (mean age 12.8 years) recruited from 10 high schools in Montreal, Canada in 1999-2000, who were followed into young adulthood. Cigarette consumption was measured every 3 months during high school, and again at mean age 20.4 and 24.0. Analyses using time since onset of smoking as the time metric was restricted to 307 incident smokers; analysis using calendar time included 645 prevalent and incident smokers. Smoking status and nicotine dependence (ND) were assessed at mean age 20.4 and 24.0. Simulated data mimicked the real study during high school.

RESULTS

Use of different time metrics resulted in different numbers and shapes of trajectories in the simulated and real datasets. Participants in the calendar time analyses reported more ND in young adulthood, reflecting inclusion of 388 prevalent smokers who had smoked for longer durations.

CONCLUSIONS

Choosing the right time metric for trajectory analysis should be balanced against research intent. Trajectory analyses using the time since onset metric depict the natural course of smoking in incident smokers. Those using calendar time offer a snapshot of smoking across age during a given time period.

IMPLICATIONS

This study uses simulated and real data to show that trajectory analyses of cigarette smoking that use calendar time (e.g., age) versus time since onset as the time axis metric tell a different story. Trajectory analyses using the time since onset metric depict the natural course of smoking in incident smokers. Those using calendar time offer a snapshot of smoking across age during a given time period. Choosing the right time metric should be balanced against research intent.

Parents, Peers, and Trajectories of Cigarette Smoking: A Group-Based Approach

This study examines the independent, relative, and additive associations between both parent and peer role models and longitudinal patterns of smoking across adolescence and early adulthood. An analysis of data from the National Longitudinal Study of Adolescent to Adult Health (N=10,166) reveals at least four distinct trajectories of smoking across ages 13-35: (1) non-smokers; (2) late peak (almost 10 cigarettes per day around age 30); (3) an early peak group that reached roughly 10 cigarettes per day around age 20 and declined; and (4) a high group that increased during adolescence and early adulthood and then remained high. Parent and peer smoking behaviors were associated with trajectory group membership net of controls for sociodemographic characteristics, parental SES, parent-child relations, and the availability of cigarettes in the family home. Parents and peers appear to have at least some independent associations net of each other, but their combined effects are powerful.

Initial engagement and persistence of health risk behaviors through adolescence: longitudinal findings from urban South Africa

Background

Little is known about longitudinal patterns of adolescent health risk behavior initial engagement and persistence in low- and middle-income countries.

Methods

Birth to Twenty Plus is a longitudinal birth cohort in Soweto-Johannesburg, South Africa. We used reports from Black African participants on cigarette smoking, alcohol, cannabis, illicit drug, and sexual activity initial engagement and adolescent pregnancy collected over 7 study visits between ages 11 and 18 y. We fit Kaplan-Meier curves to estimate behavior engagement or adolescent pregnancy, examined current behavior at age 18 y by age of first engagement, and performed a clustering analysis to identify patterns of initial engagement and their sociodemographic predictors.

Results

By age 13 y, cumulative incidence of smoking and alcohol engagement were each > 21%, while the cumulative incidence of other behaviors and adolescent pregnancy were < 5%. By age 18 y (15 y for cannabis), smoking, alcohol, and sexual activity engagement estimates were each > 65%, cannabis and illicit drug engagement were each > 16%; adolescent pregnancy was 31%. Rates of engagement were higher among males. Current risk behavior activity at age 18 y was generally unrelated to age of initial engagement. We identified three clusters reflecting low, moderate, and high-risk patterns of initial risk behavior engagement. One-third of males and 17% of females were assigned to the high-risk cluster. Sociodemographic factors were not associated with cluster membership.

Conclusions

Among urban dwelling Black South Africans, risk behavior engagement across adolescence was common and clustered into distinct patterns of initial engagement which were unrelated to the sociodemographic factors assessed. Patterns of initial risk behavior engagement may inform the timing of primary and secondary public health interventions and support integrated prevention efforts that consider multiple behaviors simultaneously.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-020-02486-y.

'Time to first tobacco cigarette soon after waking' occurs more often among underage newly incident smokers in the United States, 2004-2017

AIMS

Time to first cigarette (TTFC) after waking is a highly regarded and readily measured manifestation of a tobacco dependence process. We aim to estimate short TTFC as it occurs very soon after the onset of cigarette smoking (CS) in a community sample of newly incident smokers, all 12-21 years of age, and to study risk variation with the age of CS onset.

METHODS

United States National Surveys on Drug Use and Health, 2004-2017, drew large nationally representative samples of 12-to-21-year-old community residents, and used computerized self-interviews to measure tobacco cigarette smoking, the Fagerstrom TTFC construct, and related variables. A 'short' TTFC was defined as smoking the first cigarette after waking up within 30 min vs. 'long' TTFC or smoking more than 30 min. We studied 8188 newly incident smokers, all assessed within six months after the first puff. Estimated age-specific cumulative incidence proportions (CIP) and odds ratios (OR) are estimated and compared, with due attention to complex survey design and weights.

RESULTS

Among underage newly incident smokers (12-17 years old), an estimated 5.2% experienced short TTFC within 6 months after CS onset (95% CI = 4.4%, 6.2%), versus 3.7% for older new smokers (18-21 years; 95% CI = 2.8%, 4.6%). Underage smokers are 1.5 times more likely to develop short TTFC compared to older initiates (95% CI = 1.1, 2.1). No male-female variations are seen, but exploratory analysis disclosed findings that involve Census-defined race-ethnicity subgroups. Non-Hispanic African-American initiates are twice as likely to develop short TTFC, and Hispanic initiates are less likely to develop short TTFC, as compared with non-Hispanic White smokers.

CONCLUSIONS

Based on US community samples our study offers new evidence about TTFC formation observed within six months after the first puff when cigarette smoking starts before age 18 years.

Latent Trajectories and Profiles of Commercial Cigarette Smoking Frequency From Adolescence to Young Adulthood Among North American Indigenous People

INTRODUCTION

North American Indigenous people (ie, American Indian/Alaska Native and Canadian First Nations) have the highest rates of commercial cigarette smoking, yet little is known about long-term trajectories of use among this population. The purpose of this study is to examine heterogeneous trajectories and profiles of Indigenous cigarette use frequency from early adolescence (mean age: 11.1 years) to young adulthood (mean age: 26.3 years).

AIMS AND METHODS

Data come from a nine-wave prospective longitudinal study spanning early adolescence through young adulthood among Indigenous people in the Upper Midwest of the United States and Canada (N = 706). Smoking frequency was examined at each wave, and latent class growth analysis was used to examine heterogeneous patterns. Early adolescent and young adult demographics and smoking-related characteristics were examined across these latent trajectory groups.

RESULTS

In young adulthood, 52% of participants smoked daily/near-daily, and an additional 10% smoked weekly or monthly. Four latent trajectory groups emerged: low/non-smokers (35.2%) who had low probabilities of smoking across the study; occasional smokers (17.2%) who had moderate probabilities of smoking throughout adolescence and declining probabilities of smoking into young adulthood; mid-adolescent onset smokers (21.6%) who showed patterns of smoking onset around mid-adolescence and escalated to daily use in young adulthood; and early-adolescent onset smokers (25.9%) who showed patterns of onset in early adolescence and escalated to stable daily use by late adolescence.

CONCLUSIONS

The findings suggest multiple critical periods of smoking risk, as well as a general profile of diverse smoking frequency patterns, which can inform targeted intervention and treatment programming.

IMPLICATIONS

Nearly two-thirds (62%) of this sample of Indigenous people were current smokers by early adulthood (mean age = 26.3 years), which is substantially higher than national rates in the United States and Canada. Moreover, in all but one trajectory group, smoking prevalence consistently increased over time, suggesting these rates may continue to rise into adulthood. The longitudinal mixture modeling approach used in this study shows that smoking patterns are heterogeneous, and implications for public health policy likely vary across these diverse patterns characterized by timing of onset of use, escalation in frequency of use, and stability/change over time.

A systematic review of cigarette smoking trajectories in adolescents

Trajectory analyses differentiate subgroups of smokers based on early patterns of cigarette use, but no study has summarized this literature. We systematically reviewed the literature on adolescent cigarette smoking trajectories to document the number and shapes of trajectories identified, assess if certain study characteristics influence the number or shapes of trajectories identified, summarize factors associated with and outcomes of trajectory group membership, and assess whether the results of trajectory analyses help identify windows of opportunity for intervention. We searched PubMed and EMBASE (1/1/1980 to 1/11/2018) and identified 1695 articles. Forty-three articles with data from 37 unique datasets were retained. Each trajectory was categorized into one of three groups (i.e., low-stable, increasing, other). Number of trajectories ranged from 2 to 6 (mode = 4); 44-76% of participants were low-stable cigarette consumers, 11-21% increased consumption, and 3-11% were categorized as "other." Number of data points, smoking indicator used, and time axis influenced the number of trajectories identified. Only two articles depicted the natural course of smoking since onset. Factors associated with trajectory membership included age, sex/gender, race/ethnicity, parental education, behavior problems, depression, academic performance, baseline cigarette use, parental and friends smoking, alcohol use, and cannabis use. Outcomes included illicit drug and alcohol use. Beyond parsimoniously describing cigarette smoking patterns, it is not clear whether trajectory analyses offer increased insight into the natural course, determinants or outcomes of cigarette smoking in ways that inform the development of intervention.

Adolescent Substance Use and the Brain: Behavioral, Cognitive and Neuroimaging Correlates

Adolescence is an important ontogenetic period that is characterized by behaviors such as enhanced novelty-seeking, impulsivity, and reward preference, which can give rise to an increased risk for substance use. While substance use rates in adolescence are generally on a decline, the current rates combined with emerging trends, such as increases in e-cigarette use, remain a significant public health concern. In this review, we focus on the neurobiological divergences associated with adolescent substance use, derived from a cross-sectional, retrospective, and longitudinal studies, and highlight how the use of these substances during adolescence may relate to behavioral and neuroimaging-based outcomes. Identifying and understanding the associations between adolescent substance use and changes in cognition, mental health, and future substance use risk may assist our understanding of the consequences of drug exposure during this critical window.

Religion/Spirituality and Gender-Differentiated Trajectories of Depressive Symptoms Age 13-34

Studies examining religion/spirituality (R/S) and depressive symptoms report divergent findings, often depending on the types of variables considered. This study assessed whether subjective and experiential R/S variables were associated with increased depressive symptom burden from adolescence to young adulthood. Variations by gender were also assessed. Using group-based trajectory modeling with a cohort-sequential design, four distinct symptom trajectories were identified for women and five for men. 27.4% of women and 10.2% of men were classified on peak trajectory groups. Religious attendance was protective for men and women. Prayer was protective for women but linked to risk for men. Born-again and life-changing spiritual experiences, along with belief in supernatural leading and angelic protection, were broadly associated with increased classification on elevated symptom trajectories. In one exception, belief in supernatural leading was associated among some men with decreased risk of depressive symptoms during adolescence. Researchers must take a variety of R/S variables into account when assessing depressive symptoms, not simply religious attendance, prayer frequency, or affiliation as is commonly practiced. Religion and spirituality are multidimensional and in some cases may operate differently for men than women vis-à-vis mental well-being.

The role of negative affect in the persistence of nicotine dependence among alternative high school students: A latent growth curve analysis

BACKGROUND

Previous research has demonstrated how negative affect (i.e., depression, anxiety, stress) is often a correlate of and precursor to nicotine dependence. Although recent evidence shows a gradual decline in tobacco use in the United States, subgroups that report higher levels of negative affect may continue to be at risk of becoming dependent on nicotine. One high-risk subgroup is students who attend alternative high schools. The current longitudinal investigation examined the effect of negative affect on nicotine dependence in this youth population.

METHODS

1060 students from 29 alternative high schools in Southern California completed a series of attitudinal and behavioral measures once per year over a three-year period. The main outcome was nicotine dependence i.e., feeling a strong urge to use nicotine products or experiencing withdrawal symptoms after a period of abstinence, measured using a version of the Fagerstrom Tolerance Questionnaire designed for adolescents. A latent growth curve model was utilized to examine the effect of negative affect on nicotine dependence during this timeframe.

RESULTS

The analysis revealed that negative affect had both a concurrent and prospective relationship with nicotine dependence. Moreover, the association between negative affect and nicotine dependence in the present was not statistically significant once the influence of negative affect reported one year earlier was accounted for.

CONCLUSIONS

Negative affect may play a critical role in the persistence of nicotine dependence among high-risk youth. Providing resources to help manage negative affect may be critical to curtailing nicotine dependence in this population.

The rise of e-cigarettes, pod mod devices, and JUUL among youth: Factors influencing use, health implications, and downstream effects

BACKGROUND

Electronic cigarettes (e-cigarettes) were first introduced in the U.S. market in 2006, with the more recent evolution of "pod-mod" e-cigarettes such as JUUL introduced in 2015. Although marketed as a smoking cessation tool, e-cigarettes are rarely used for this purpose in youth. This review aims to synthesize the literature regarding e-cigarette use among youth, and provides a resource for clinicians, educators, and families that helps answer commonly asked questions about e-cigarettes.

METHODS

PubMed, Scopus, and PsycINFO search was performed using search terms "Electronic Nicotine Delivery Systems," "e cigarettes," "e-cigarettes," "electronic cigarettes," "vaping," "JUUL," "e-cigs," and "vape pens." Search results were filtered to only include those related to adolescents and young adults.

RESULTS

E-cigarette use among youth is common, with rates of use increasing from 1.5% in 2011 to 20.8% in 2018. Pod mod devices such as JUUL have gained favor among youth for their sleek design, user-friendly function, desirable flavors, and ability to be used discreetly in places where smoking is forbidden. Adolescents are often uninformed about the constituents of e-cigarettes, and little is known about the long-term effects of e-cigarettes. Studies have suggested a "gateway" effect for combustible cigarettes and cannabis use.

CONCLUSIONS

E-cigarette use is becoming increasingly common among youth, leading to a myriad of questions and concerns from providers, educators, and family members. More research is needed to determine the ultimate public health impact of e-cigarette use. The authors provide a summary table of frequently asked questions in order to help clarify these common concerns.

Mind the gap: A review and recommendations for statistically evaluating Dual Systems models of adolescent risk behavior

According to Dual Systems models (Casey et al., 2008; Luna and Wright, 2016; Steinberg, 2008), a rapidly-developing socioemotional system and gradually-developing cognitive control system characterize adolescent brain development. The imbalance hypothesis forwarded by Dual Systems models posits that the magnitude of the imbalance between these two developing systems should predict the propensity for engaging in a variety of risk behaviors. The current integrative review argues that the excitement generated by the imbalance hypothesis and its implications for explaining adolescent risk behaviors has not been meet with equal efforts to rigorously test this hypothesis. The goal of the current review is to help guide the field to consider appropriate and rigorous methods of testing the imbalance hypothesis. First, we review the analytic approaches that have been used to test the imbalance hypothesis and outline statistical and conceptual limitations of these approaches. Next, we discuss the utility of two longitudinal analytic approaches (Latent Difference Scores and Growth Mixture Modeling) for testing the imbalance hypothesis. We utilize data from a large community adolescent sample to illustrate each approach and argue that Latent Difference Scores and Growth Mixture Modeling approaches enhance the specificity and precision with which the imbalance hypothesis is evaluated.

E-cigarette Use and Subsequent Smoking Frequency Among Adolescents

: media-1vid110.1542/5839992666001PEDS-VA_2018-0486Video Abstract BACKGROUND AND OBJECTIVES: Electronic cigarette (e-cigarette) use is associated with cigarette initiation among adolescents. However, it is unclear whether e-cigarette use is associated with more frequent cigarette use after initiation. Also, the extent to which cigarette or dual cigarette and e-cigarette users transition to exclusive e-cigarette use or to the nonuse of either product is not yet known.

METHODS

Data were pooled from 3 prospective cohort studies in California and Connecticut (baseline: 2013-2014; follow-up: 2014-2016; N = 6258). Polytomous regression models were used to evaluate the association of baseline e-cigarette use (never or ever) with cigarette use frequency at follow-up (experimental: initiation but no past-30-day use; infrequent: 1-2 of the past 30 days; frequent: 3-5 or more of the past 30 days). Polytomous regression models were also used to evaluate transitions between baseline ever or past-30-day single or dual product use and past-30-day single or dual product use at follow-up.

RESULTS

Among baseline never smokers, e-cigarette users had greater odds of subsequent experimental (odds ratio [OR] = 4.58; 95% confidence interval [CI]: 3.56-5.88), infrequent (OR = 4.27; 95% CI: 2.75-6.62) or frequent (OR = 3.51; 95% CI: 1.97-6.24) cigarette use; the 3 OR estimates were not significantly different. Baseline past-30-day exclusive cigarette use was associated with higher odds at follow-up of exclusive cigarette or dual product use than of exclusive e-cigarette use.

CONCLUSIONS

Tobacco control policy to reduce adolescent use of both e-cigarettes and cigarettes is needed to prevent progression to more frequent tobacco use patterns and reduce combustible cigarette use (with or without concurrent e-cigarette use) to lessen the adverse public health impact of e-cigarettes.

Do Classes of Polysubstance Use in Adolescence Differentiate Growth in Substances Used in the Transition to Young Adulthood?

BACKGROUND

Past studies have differentiated classes of polysubstance use in adolescence, however, the associations of adolescent polysubstance use classes with longitudinal substance use trajectories from adolescence to young adulthood have not been studied.

OBJECTIVE

The current study examined substance use classes during adolescence and longitudinal trajectories of each substance used across the transition to young adulthood.

METHOD

Data were collected biennially from 662 youth and followed 10 years across six measurement assessments. Using baseline data (T1), latent class analysis was used to identify classes of polysubstance use (cigarette, alcohol, marijuana, and illicit drug use) during adolescence. Using T2 through T6 data, we fit latent growth models for cigarette, alcohol, marijuana, and illicit drug use to examine longitudinal trajectories of each substance used by class.

RESULTS

A three-class model fit the data best and included a poly-use class, that had high probabilities of use among all substances, a co-use class, that had high probabilities of use among alcohol and marijuana, and a low-use class that had low probabilities of use among all substances. We then examined trajectories of each substance used by class. Strong continuity of substance use was found by class across 14 years. Additionally, for some substances, higher average levels of use of at age 14 were associated with change in growth of other substances used over time. Conclusions/Importance: Efforts that only target a single drug type may be missing an important opportunity to reduce the use and subsequent consequences related to the use of multiple substances.

Skew t Mixture Latent State-Trait Analysis: A Monte Carlo Simulation Study on Statistical Performance

This simulation study assessed the statistical performance of a skew t mixture latent state-trait (LST) model for the analysis of longitudinal data. The model aims to identify interpretable latent classes with class-specific LST model parameters. A skew t-distribution within classes is allowed to account for non-normal outcomes. This flexible function covers heavy tails and may reduce the risk of identifying spurious classes, e.g., in case of outliers. Sample size, number of occasions and skewness of the trait variable were varied. Generally, parameter estimation accuracy increases with increasing numbers of observations and occasions. Larger bias compared to other parameters occurs for parameters referring to the skew t-distribution and variances of the latent trait variables. Standard error estimation accuracy shows diffuse patterns across conditions and parameters. Overall model performance is acceptable for large conditions, even though none of the models is free from bias. The application of the skew t mixture model in case of large numbers of occasions and observations may be possible, but results should be treated with caution. Moreover, the skew t approach may be useful for other mixture models.

Association between elementary school personality and high school smoking and drinking

BACKGROUND AND AIMS

Among US high school students, alcohol consumption and cigarette smoking are associated with numerous concurrent and future harms. We tested whether multiple elementary school personality dispositions to behave impulsively can predict these addictive behaviors invariably across gender and race.

DESIGN AND SETTING

This longitudinal design involved testing whether individual differences on impulsigenic traits in elementary school predicted drinking and smoking 4 years later in high school in 23 public schools in Kentucky, USA.

PARTICIPANTS

A total of 1897 youth, mean age 10.33 at wave 1, drawn from urban, rural and suburban backgrounds.

MEASUREMENTS

Drinking and smoking frequency were assessed by single-item questions. The key predictors were impulsigenic traits measured with the UPPS-P Child Version impulsive behavior scale. Important covariates included were pubertal status, depression, negative affect and positive affect; each was assessed by self-report.

FINDINGS

Three personality traits measured in 5th grade, each representing different dispositions to engage in impulsive behavior, predicted drinking and smoking in 9th grade above and beyond other risk factors and 5th grade drinking and smoking. Specifically, urgency (b = 0.10, 0.13), sensation-seeking (b = 0.13, 0.07) and low conscientiousness (b = 0.14, 0.11) each uniquely predicted both high school drinking and smoking, respectively. There was no evidence that any trait predicted either outcome more strongly than the other traits, nor was there evidence that predictive results varied by gender or race.

CONCLUSIONS

Three personality traits (urgency, sensation-seeking and low conscientiousness), when measured in 11-year-old children, predict those children's drinking and smoking behavior individually at age 15. The effects are invariant across gender and race.

Investigating Approaches to Estimating Covariate Effects in Growth Mixture Modeling: A Simulation Study

Researchers continue to be interested in efficient, accurate methods of estimating coefficients of covariates in mixture modeling. Including covariates related to the latent class analysis not only may improve the ability of the mixture model to clearly differentiate between subjects but also makes interpretation of latent group membership more meaningful. Very few studies have been conducted that compare the performance of various approaches to estimating covariate effects in mixture modeling, and fewer yet have considered more complicated models such as growth mixture models where the latent class variable is more difficult to identify. A Monte Carlo simulation was conducted to investigate the performance of four estimation approaches: (1) the conventional three-step approach, (2) the one-step maximum likelihood (ML) approach, (3) the pseudo class (PC) approach, and (4) the three-step ML approach in terms of their ability to recover covariate effects in the logistic regression class membership model within a growth mixture modeling framework. Results showed that when class separation was large, the one-step ML approach and the three-step ML approach displayed much less biased covariate effect estimates than either the conventional three-step approach or the PC approach. When class separation was poor, estimation of the relation between the dichotomous covariate and latent class variable was severely affected when the new three-step ML approach was used.

Body mass index, body dissatisfaction and adolescent smoking initiation

BACKGROUND

Smoking influences body weight, but there is little evidence as to whether body mass index (BMI) and body dissatisfaction increase smoking initiation in adolescents.

METHODS

We evaluated the association between measured BMI, body dissatisfaction and latent classes of smoking initiation (never smokers, experimenters, late onset regular smokers, early onset regular smokers) in the Avon Longitudinal Study of Parents and Children. In observational analyses we used BMI (N=3754) and body dissatisfaction at age 10.5 years (N=3349). In Mendelian randomisation (MR) analysis, we used a BMI genetic risk score of 76 single nucleotide polymorphisms (N=4017).

RESULTS

In females, higher BMI was associated with increased odds of early onset regular smoking (OR: 1.11, 95% CI: 1.04, 1.18) compared to being a never smoker, but not clearly associated with experimenting with smoking (OR: 1.04, 95% CI: 0.99, 1.10) or late onset regular smoking (OR: 1.01, 95% CI: 0.94, 1.09). No clear evidence was found for associations between BMI and smoking initiation classes in males (p-value for sex interaction≤0.001). Body dissatisfaction was associated with increased odds of late-onset regular smoking (OR: 1.71, 95% CI: 1.32, 1.99) in males and females combined (P-value for sex interaction=0.32). There was no clear evidence for an association between the BMI genetic risk score and smoking latent classes in males or females but estimates were imprecise.

CONCLUSIONS

BMI in females and body dissatisfaction in males and females are associated with increased odds of smoking initiation, highlighting these as potentially important factors for consideration in smoking prevention strategies.

Latent Growth Curve Models for Biomarkers of the Stress Response

Objective: The stress response is a dynamic process that can be characterized by predictable biochemical and psychological changes. Biomarkers of the stress response are typically measured over time and require statistical methods that can model change over time. One flexible method of evaluating change over time is the latent growth curve model (LGCM). However, stress researchers seldom use the LGCM when studying biomarkers, despite their benefits. Stress researchers may be unaware of how these methods can be useful. Therefore, the purpose of this paper is to provide an overview of LGCMs in the context of stress research. We specifically highlight the unique benefits of using these approaches. Methods: Hypothetical examples are used to describe four forms of the LGCM. Results: The following four specifications of the LGCM are described: basic LGCM, latent growth mixture model, piecewise LGCM, and LGCM for two parallel processes. The specifications of the LGCM are discussed in the context of the Trier Social Stress Test. Beyond the discussion of the four models, we present issues of modeling nonlinear patterns of change, assessing model fit, and linking specific research questions regarding biomarker research using different statistical models. Conclusions: The final sections of the paper discuss statistical software packages and more advanced modeling capabilities of LGCMs. The online Appendix contains example code with annotation from two statistical programs for the LCGM.

Trajectories of Cigarette Smoking From Teens to Young Adulthood: 2000 to 2013

PURPOSE

To identify trajectories of smoking behaviors of a cohort of youth followed through young adulthood from 2000 to 2013.

DESIGN

The Minnesota Adolescent Community Cohort study, a population-based cohort study.

SETTING

Nationwide, originating in the Midwestern United States.

PARTICIPANTS

Cohort of youth surveyed for 14 years beginning at ages 12 to 16 (N = 4241 at baseline; 59% recruitment rate).

MEASURES

Main variable of interest was the number of days smoked in the past 30 days. Also included time-varying and time-invariant covariates.

ANALYSIS

We utilized growth mixture modeling to group individuals into trajectories over time.

RESULTS

We identified 5 distinct trajectories: nonsmokers (59.5%), early-onset regular smokers (14.2%), occasional smokers (11.5%), late-onset regular smokers (9.4%), and quitters (5.3%). Adjusted models showed that early- and late-onset regular smokers (compared to nonsmokers) had lower odds of attending or graduating from a 4-year college ( P < .05). Participants in all smoking classes compared to nonsmokers had greater odds of having more close friends who smoked ( P < .05).

CONCLUSION

Our results show that individuals in their teens through young adulthood can be classified into 5 smoking trajectories. More people in this age range remained abstainers than found in most previous studies; however, a sizable group was identified as regular smokers by the time they reached young adulthood. Interventions targeted at teens, including those that address social and environmental influences, are clearly still needed to prevent escalation of smoking as they move toward young adulthood.

Can tobacco dependence provide insights into other drug addictions?

Within the field of addiction research, individuals tend to operate within silos of knowledge focused on specific drug classes. The discovery that tobacco dependence develops in a progression of stages and that the latency to the onset of withdrawal symptoms after the last use of tobacco changes over time have provided insights into how tobacco dependence develops that might be applied to the study of other drugs.As physical dependence on tobacco develops, it progresses through previously unrecognized clinical stages of wanting, craving and needing. The latency to withdrawal is a measure of the asymptomatic phase of withdrawal, extending from the last use of tobacco to the emergence of withdrawal symptoms. Symptomatic withdrawal is characterized by a wanting phase, a craving phase, and a needing phase. The intensity of the desire to smoke that is triggered by withdrawal correlates with brain activity in addiction circuits. With repeated tobacco use, the latency to withdrawal shrinks from as long as several weeks to as short as several minutes. The shortening of the asymptomatic phase of withdrawal drives an escalation of smoking, first in terms of the number of smoking days/month until daily smoking commences, then in terms of cigarettes smoked/day.The discoveries of the stages of physical dependence and the latency to withdrawal raises the question, does physical dependence develop in stages with other drugs? Is the latency to withdrawal for other substances measured in weeks at the onset of dependence? Does it shorten over time? The research methods that uncovered how tobacco dependence emerges might be fruitfully applied to the investigation of other addictions.

Substance use Trajectories from Early Adolescence to Emerging Adulthood: A Comparison of Smoking, Binge Drinking, and Marijuana use

Over the past several years, there has been growing interest in identifying distinct developmental trajectories of substance use. Using data from the RAND Adolescent/Young Adult Panel Study (N = 6,527), we synthesize our prior findings on patterns of smoking, binge drinking, and marijuana use from early adolescence (age 13) to emerging adulthood (age 23). We also present new data on how these trajectory classes compare on key psychosocial and behavioral outcomes during emerging adulthood. For each type of substance use, we found two periods of vulnerability: early adolescence and the transition to emerging adulthood. As expected, early users were at relatively high risk for poor outcomes at age 23 compared to consistent low-level users and abstainers, even if they reduced their use during adolescence. However, youths who were not early users, but steadily increased their use over time, also tended to be at relatively high risk. Results suggest that multiple prevention approaches might be needed to successfully reach at-risk youths.

Psychosocial Correlates of Smoking Trajectories Among Urban African American Adolescents

Little is known of smoking trajectories or of the correlates of smoking trajectories among African American youth. Ninth-grade African American adolescents (n = 566) were interviewed in Year 1 and then were subsequently interviewed annually for 3 additional years. Five trajectories of cigarette smokers were identified: abstainers, experimenters/consistent light smokers, consistent regular smokers, accelerators, and quitters. Psychological well-being at Year 1 was lower among consistent regular smokers and accelerators as compared to abstainers. Variance in other problem behaviors mirrored the smoker trajectories. At Year 4,the abstainers and experimenters/consistent light smokers reported greater participation in sports activities as compared to the quitters, whereas the abstainers reported greater participation in other school activities as compared to the consistent regular smokers.

Do Adolescent Sexual Behavior and Intention to Engage in Sexual Behavior Change in High School Years in Hong Kong?

STUDY OBJECTIVE

In this study we examined sexual behavior and intention to engage in sexual behavior among Chinese high school students in Hong Kong using 6 waves of data collected over 6 years. We also focused on the related sociodemographic and family correlates. DESIGN, SETTING, PARTICIPANTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: A 6-year longitudinal study was conducted. At each wave, a questionnaire was used to collect data on sociodemographic characteristics, positive youth development, and family functioning in the respondents.

RESULTS

Individual growth curve models showed that adolescent sexual behavior and intention increased over time. Adolescents with higher levels of positive youth development reported lower levels of past sexual behavior. Youths from better-off and higher functioning families increased their sexual behavior at slower rates than did youths from families with economic disadvantage and poor family functioning. Regarding intention to have sex, older adolescents reported higher levels of intention. Youngsters with higher levels of perceived family functioning and positive youth development reported lower levels of initial intention. Adolescent boys increased their intention at a faster rate than did girls.

CONCLUSION

Findings from the study identified risk factors (ie, age, gender, and economic disadvantage) and protective factors (ie, healthy family functioning, positive youth development) that influence the levels and growth rates of adolescent sexual behavior and intention. Implications for future research and interventions are discussed.

Gambling behaviors and attitudes in adolescent high-school students: Relationships with problem-gambling severity and smoking status

BACKGROUND AND AIMS

Smoking is associated with more severe/extensive gambling in adults. The purpose of this study was to examine relationships between smoking and gambling in adolescents.

METHODS

Analyses utilized survey data from 1591 Connecticut high-school students. Adolescents were classified by gambling (Low-Risk Gambling [LRG], At Risk/Problem Gambling [ARPG]) and smoking (current smoker, non-smoker). The main effects of smoking and the smoking-by-gambling interactions were examined for gambling behaviors (e.g., type, location), and gambling attitudes. Data were analyzed using chi-square and logistic regression; the latter controlled for gender, race/ethnicity, grade, and family structure.

RESULTS

For APRG adolescents, smoking was associated with greater online, school, and casino gambling; gambling due to anxiety and pressure; greater time spent gambling; early gambling onset; perceived parental approval of gambling; and decreased importance of measures to prevent teen gambling. For LRG adolescents, smoking was associated with non-strategic gambling (e.g., lottery gambling); school gambling; gambling in response to anxiety; gambling for financial reasons; greater time spent gambling; and decreased importance of measures to prevent teen gambling. Stronger relationships were found between smoking and casino gambling, gambling due to pressure, earlier onset of gambling, and parental perceptions of gambling for ARPG versus LRG adolescents.

DISCUSSION

Smoking is associated with more extensive gambling for both low- and high-risk adolescent gamblers.

CONCLUSION

Smoking may be a marker of more severe gambling behaviors in adolescents and important to consider in gambling prevention and intervention efforts with youth.

Dual Trajectories of Cigarette Smoking and Smokeless Tobacco Use From Adolescence to Midlife Among Males in a Midwestern US Community Sample

INTRODUCTION

Identifying trajectories of tobacco use is critical for understanding its natural history and targeting interventions, but research on trajectories of smokeless tobacco and dual use of smokeless tobacco and cigarettes is very limited. This study identified tobacco use trajectories from adolescence to midlife and tested correlates of trajectory group membership.

METHODS

This study included all male participants in a longitudinal study who reported cigarette smoking or smokeless tobacco use in 1987, 1993, 1999, 2005, or 2011 (N = 2230). Group-based trajectory analyses were conducted with zero-inflated Poisson models. Analysis of covariance was used to test adolescent health beliefs associated with trajectory group membership.

RESULTS

Five smoking trajectory groups were identified: (1) consistent abstinence from cigarettes; (2) late onset intermittent, then cessation; (3) early onset regular, then cessation; (4) delayed onset regular, then cessation; and (5) consistent regular. Four smokeless tobacco trajectory groups were identified: (1) early onset, then cessation; (2) consistent abstinence from smokeless tobacco; (3) late onset, escalating; and (4) consistent regular. The proportion of participants in trajectory groups representing dual use was low. Adolescent beliefs favorable to smoking and smokeless tobacco were associated with membership in consistent regular use groups.

CONCLUSIONS

The prevalence of dual use of cigarettes and smokeless tobacco was low, and there was little evidence to suggest switching between tobacco products. Participants who held more positive beliefs about smoking and smokeless tobacco as adolescents were more likely to be consistent regular users of cigarettes and smokeless tobacco into adulthood.

Pathways to change: Use trajectories following trauma-informed treatment of women with co-occurring post-traumatic stress disorder and substance use disorders

INTRODUCTION AND AIMS

Despite advances towards integration of care for women with co-occurring substance use disorder (SUD) and post-traumatic stress disorder (PTSD), low abstinence rates following SUD/PTSD treatment remain the norm. The utility of investigating distinct substance use trajectories is a critical innovation in the detection and refining of effective interventions for this clinical population.

DESIGN AND METHODS

The present study reanalysed data from the largest randomised clinical trial to date for co-occurring SUD and PTSD in women (National Drug Abuse Treatment Clinical Trials Network; Women and Trauma Study). Randomised participants (n = 353) received one of two interventions in addition to treatment as usual for SUD: (i) trauma-informed integrative treatment for PTSD/SUD; or (ii) an active control psychoeducation course on women's health. The present study utilised latent growth mixture models (LGMM) with multiple groups to estimate women's substance use patterns during the 12-month follow-up period.

RESULTS

Findings provided support for three different trajectories of substance use in the post-treatment year: (i) consistently low likelihood and use frequency; (ii) consistently high likelihood and use frequency; and (iii) high likelihood and moderate use frequency. Covariate analyses revealed improvement in PTSD severity was associated with membership in a specific substance use trajectory, although receiving trauma-informed treatment was not. Additionally, SUD severity, age and after-care efforts were shown to be related to trajectory membership.

DISCUSSION AND CONCLUSIONS

Findings highlight the necessity of accounting for heterogeneity in post-treatment substance use, relevance of trauma-informed care in SUD recovery and benefits of incorporating methodologies like LGMM when evaluating SUD treatment outcomes.

Cigarette smoking, problem-gambling severity, and health behaviors in high-school students

Introduction

Smoking and gambling are two significant public health concerns. Little is known about the association of smoking and gambling in adolescents. The current study of high-school adolescents examined: (1) smoking behavior by problem-gambling severity and (2) health-related variables by problem-gambling severity and smoking status.

Methods

Analyses utilized survey data from 1591 Connecticut high-school students. Adolescents were classified by problem-gambling severity (Low-Risk Gambling [LRG], At-Risk/Problem Gambling [ARPG]) and smoking status (current smoker, non-smoker). Analyses examined the smoking behavior of ARPG versus LRG adolescents as well as the smoking-by-problem-gambling-severity interactions for health and well-being measures (e.g., grades, substance use). Chi-square and logistic regression analyses were used; the latter controlled for gender, race/ethnicity, school grade, and family structure.

Results

More adolescents with ARPG than LRG reported regular smoking, heavy smoking, early smoking onset, no smoking quit attempts, and parental approval of smoking. ARPG and LRG adolescents who smoked were more likely to report poor grades, lifetime use of marijuana and other drugs, current heavy alcohol use, current caffeine use, depression, and aggressive behaviors and less likely to report participation in extracurricular activities. The association between not participating in extracurricular activities and smoking was statistically stronger in the LRG compared to the ARPG groups. Post-hoc analyses implicated a range of extracurricular activities including team sports, school clubs, and church activities.

Conclusions

Smoking was associated with poorer health-related behaviors in both ARPG and LRG groups. Interventions with adolescents may benefit from targeting both smoking and gambling.

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We examined adolescent health behaviors by smoking status and gambling severity.

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Smoking was associated with poorer health behaviors for adolescent gamblers.

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Considering smoking may be helpful in interventions with adolescent gamblers.

Alcohol and Substance Use in Adolescence and Young Adulthood: The Role of Siblings

Interpersonal relationships both within and outside the family have been a central part of alcohol and substance use research. Many studies have focused on the role of parents and peers; fewer studies have focused on siblings. This paper examined siblings' roles in ATOD use patterns and trajectories in the context of familial and non-familial factors across time. First, intraclass correlations (ICCs) were used to examine the degree to which older siblings' ATOD use was associated with younger siblings' ATOD use. Second, hierarchical regression analyses were conducted to examine the degree to which individual, parent, sibling and peer factors over time were associated with adolescents' and young adults' ATOD use. It should be noted that developmentally proximal predictors were utilized in these models and within-family replication was also examined. Results demonstrate strong associations between older and younger siblings' ATOD use. Moreover, the developmentally proximal sibling variables were predictive of younger sibling ATOD use in the context of other variables across all substances. Study findings are discussed in terms of identifying promising and potentially malleable points of intervention for future investigators.

Alcohol, marijuana, and tobacco use trajectories from age 12 to 24 years: demographic correlates and young adult substance use problems

Substance use trajectories were examined from early adolescence to young adulthood among a diverse sample of 998 youths. Analysis of longitudinal data from ages 12 to 24 identified distinct trajectories for alcohol, marijuana, and tobacco use. Modeling revealed 8 alcohol, 7 marijuana, and 6 tobacco use trajectories. Analyses assessed risk for substance use problems in early adulthood within each trajectory, as well as overlap among alcohol, marijuana, and tobacco use trajectories. Findings confirmed that adolescents with early- and rapid-onset trajectories are particularly vulnerable to the development of problematic substance use in early adulthood. However, analyses also identified an escalating high school onset trajectory for alcohol and for marijuana use that was equally prognostic of problem use in adulthood. Moreover, tobacco use in early adolescence was associated with developing high-risk marijuana and alcohol use patterns. Random assignment to the Family Check-Up intervention was found to reduce risk for membership in the high-risk marijuana use trajectories, suggesting that family-based approaches delivered during adolescence can prevent escalations to problematic substance use. These findings suggest the importance of developmental heterogeneity and equifinality in considering prevention for alcohol and drug use.

Parental smoking exposure and adolescent smoking trajectories

OBJECTIVE

In a multigenerational study of smoking risk, the objective was to investigate the intergenerational transmission of smoking by examining if exposure to parental smoking and nicotine dependence predicts prospective smoking trajectories among adolescent offspring.

METHODS

Adolescents (n = 406) ages 12 to 17 and a parent completed baseline interviews (2001-2004), and adolescents completed up to 2 follow-up interviews 1 and 5 years later. Baseline interviews gathered detailed information on parental smoking history, including timing and duration, current smoking, and nicotine dependence. Adolescent smoking and nicotine dependence were assessed at each time point. Latent Class Growth Analysis identified prospective smoking trajectory classes from adolescence into young adulthood. Logistic regression was used to examine relationships between parental smoking and adolescent smoking trajectories.

RESULTS

Four adolescent smoking trajectory classes were identified: early regular smokers (6%), early experimenters (23%), late experimenters (41%), and nonsmokers (30%). Adolescents with parents who were nicotine-dependent smokers at baseline were more likely to be early regular smokers (odds ratio 1.18, 95% confidence interval 1.05-1.33) and early experimenters (odds ratio 1.04, 95% confidence interval 1.04-1.25) with each additional year of previous exposure to parental smoking. Parents' current non-nicotine-dependent and former smoking were not associated with adolescent smoking trajectories.

CONCLUSIONS

Exposure to parental nicotine dependence is a critical factor influencing intergenerational transmission of smoking. Adolescents with nicotine-dependent parents are susceptible to more intense smoking patterns and this risk increases with longer duration of exposure. Research is needed to optimize interventions to help nicotine-dependent parents quit smoking early in their children's lifetime to reduce these risks.

Transitions in smoking behavior during emerging adulthood: a longitudinal analysis of the effect of home smoking bans

OBJECTIVES

We studied the effect of home smoking bans on transitions in smoking behavior during emerging adulthood.

METHODS

We used latent transition analysis to examine movement between stages of smoking from late adolescence (ages 16-18 years) to young adulthood (ages 18-20 years) and the effect of a home smoking ban on these transitions. We used data from the Minnesota Adolescent Community Cohort study collected in 2004 to 2006.

RESULTS

Overall, we identified 4 stages of smoking: (1) never smokers, (2) experimental smokers, (3) light smokers, and (4) daily smokers. Transition probabilities varied by stage. Young adults with a home ban during late adolescence were less likely to be smokers and less likely to progress to higher use later. Furthermore, the protective effect of a home smoking ban on the prevalence of smoking behavior was evident even in the presence of parental smoking. However, this effect was less clear on transitions over time.

CONCLUSIONS

In addition to protecting family members from exposure to secondhand smoke, home smoking bans appear to have the additional benefit of reducing initiation and escalation of smoking behavior among young adults.

Individual- and community-level correlates of cigarette-smoking trajectories from age 13 to 32 in a U.S. population-based sample

BACKGROUND

Characterizing smoking behavior is important for informing etiologic models and targeting prevention efforts. This study explored the effects of both individual- and community-level variables in predicting cigarette use vs. non-use and level of use among adolescents as they transition into adulthood.

METHODS

Data on 14,779 youths (53% female) were drawn from the National Longitudinal Study of Adolescent Health (Add Health); a nationally representative longitudinal cohort. A cohort sequential design allowed for examining trajectories of smoking typologies from age 13 to 32 years. Smoking trajectories were evaluated by using a zero-inflated Poisson (ZIP) latent growth analysis and latent class growth analysis modeling approach.

RESULTS

Significant relationships emerged between both individual- and community-level variables and smoking outcomes. Maternal and peer smoking predicted increases in smoking over development and were associated with a greater likelihood of belonging to any of the four identified smoking groups versus Non-Users. Conduct problems and depressive symptoms during adolescence were related to cigarette use versus non-use. State-level prevalence of adolescent smoking was related to greater cigarette use during adolescence.

CONCLUSIONS

Individual- and community-level variables that distinguish smoking patterns within the population aid in understanding cigarette use versus non-use and the quantity of cigarette use into adulthood. Our findings suggest that efforts to prevent cigarette use would benefit from attention to both parental and peer smoking and individual well-being. Future work is needed to better understand the role of variables in the context of multiple levels (individual and community-level) on smoking trajectories.

Nondaily smoking patterns in young adulthood

PURPOSE

Many young adult smokers routinely smoke less than daily. Prospective, longitudinal data are needed to describe and predict the influences on smoking patterns among nondaily young adult smokers.

METHODS

Latent class growth analysis was used to examine developmental trajectories and predictors of nondaily cigarette smoking among young adults aged 18 to 21 in the Upper Midwestern United States.

RESULTS

There were three distinct groups of nondaily smokers during young adulthood (n=519). College status, previous quit attempts, attitudes toward the meanings of cigarettes, and situational factors influencing smoking were significant predictors of group membership.

CONCLUSIONS

Nondaily smoking in young adulthood may result in several discrete patterns of smoking between age 18 and 21. Predictors that differentiate smoking trajectories may be useful to promote cessation or reduction in young adult smoking.

Trajectories of Reinforcement Sensitivity During Adolescence and Risk for Substance Use

Developmental neuroscience models suggest that changes in responsiveness to incentives contribute to increases in adolescent risk behavior, including substance use. Trajectories of sensitivity to reward (SR) and sensitivity to punishment (SP) were examined and tested as predictors of escalation of early substance use in a community sample of adolescents (N=765, mean baseline age 11.8 years, 54% female). SR and SP were assessed using a laboratory task. Across three annual assessments, SR increased, and rapid escalation was associated with increases in substance use. SP declined and was unrelated to substance use. Findings support contemporary views of adolescent brain development, and suggest that early adolescent substance use is motivated by approach responses to reward, rather than failure to avoid potential aversive consequences.

Mental disorders and smoking trajectories: a 10-year prospective study among adolescents and young adults in the community

BACKGROUND

Numerous studies have documented an association between mental disorders and onset of cigarette smoking. Yet, there is little understanding of the potential impact of mental disorders on trajectories of smoking over time. The objective of this study was to investigate this relationship among adolescents over a 10-year span.

METHODS

Data were drawn from the Early Developmental Stages of Psychopathology Study, a 10-year prospective investigation of youth in Germany. Growth mixture modeling was used to identify smoking trajectories and logistic regression analyses were used to examine relationships between mental disorders and subsequent trajectories.

RESULTS

Four trajectories were identified: non-users; increasing use; decreasing use; persistent use. Alcohol/drug use disorders, stress disorders, anxiety disorders, somatoform disorder and nicotine dependence were associated with nicotine use (as compared to the non-smoker class). However, comparisons between trajectories of nicotine use showed that any stress disorder predicted only decreasing use compared to the other two trajectories; nicotine dependence, alcohol/illicit drug use disorders as well as panic disorder and somatoform disorders were inversely associated with increasing use; nicotine dependence and alcohol/drug use disorders were associated with persistent use.

CONCLUSIONS

Several mental disorders appear to be non-specific markers of the range of smoking trajectories while others predict specific trajectories. Numerous disorders (e.g., alcohol/drug use disorders) do not appear to occur only prior to and predict increased smoking trajectory as had been previously suggested, but rather they also occur concurrently, with high levels of smoking and in some cases smoking persists at a steady level over time.

Prospective associations of internalizing and externalizing problems and their co-occurrence with early adolescent substance use

The literature is equivocal regarding the role of internalizing problems in the etiology of adolescent substance use. In this study, we examined the association of internalizing and externalizing behavior problems and their co-occurrence with early adolescent substance use to help clarify whether internalizing problems operate as a risk or protective factor. A large community sample (N = 387; mean age at the first assessment 12 years old; 83 % White/non-Hispanic) was assessed annually for 3 years. Externalizing problem behavior in the absence of internalizing problems showed the strongest prospective association with alcohol, cigarette, and marijuana use. A weaker, albeit statistically significant prospective positive association was found between co-occurring internalizing and externalizing behavior problems and substance use. Internalizing problems in the absence of externalizing problems protected adolescents against cigarette and marijuana use. Clarifying the role of internalizing problems in the etiology of adolescent substance use can inform the development of early intervention and prevention efforts. Our results highlight the importance of further considering the co-occurrence of internalizing and externalizing behavior problems in developmental pathways to substance use.

Social and generalized anxiety symptoms and alcohol and cigarette use in early adolescence: the moderating role of perceived peer norms

This study prospectively examines the association between social and generalized anxiety symptoms and alcohol and cigarette use in early adolescence and how injunctive (perceived peer approval of use) and descriptive (perceived peer use) norms may moderate the association. Sex differences were also examined. Data were taken from a longitudinal study investigating problem behavior and adolescent substance use. The community sample (N=387) was assessed annually, and data from the first two waves of assessment were used for this study. Early adolescents were between the ages of 11 and 13 at the first assessment (mean age=11.05, SD=0.55, 55% female). Peer norms moderated the association between both social and generalized anxiety symptoms and the likelihood of alcohol and cigarette use for girls, but not for boys. Specifically, girls with elevated levels of generalized anxiety symptoms were at risk for use when perceived peer use was low, and protected from use when perceived peer use was high. Girls with elevated levels of social anxiety symptoms were at risk for use when perceived peer approval of use was high, and protected from use when perceived peer approval of use was low. Past studies have found inconsistent support for an association between anxiety and adolescent substance use, and our findings provide some clarity regarding for whom and when anxiety operates as a risk/protective factor. Social context and sex are critical for understanding the role of different forms of anxiety in the etiology of adolescent alcohol and cigarette use.

Predictors of latent trajectory classes of physical dating violence victimization

This study identified classes of developmental trajectories of physical dating violence victimization from grades 8 to 12 and examined theoretically-based risk factors that distinguished among trajectory classes. Data were from a multi-wave longitudinal study spanning 8th through 12th grade (n = 2,566; 51.9 % female). Growth mixture models were used to identify trajectory classes of physical dating violence victimization separately for girls and boys. Logistic and multinomial logistic regressions were used to identify situational and target vulnerability factors associated with the trajectory classes. For girls, three trajectory classes were identified: a low/non-involved class; a moderate class where victimization increased slightly until the 10th grade and then decreased through the 12th grade; and a high class where victimization started at a higher level in the 8th grade, increased substantially until the 10th grade, and then decreased until the 12th grade. For males, two classes were identified: a low/non-involved class, and a victimized class where victimization increased slightly until the 9th grade, decreased until the 11th grade, and then increased again through the 12th grade. In bivariate analyses, almost all of the situational and target vulnerability risk factors distinguished the victimization classes from the non-involved classes. However, when all risk factors and control variables were in the model, alcohol use (a situational vulnerability) was the only factor that distinguished membership in the moderate trajectory class from the non-involved class for girls; anxiety and being victimized by peers (target vulnerability factors) were the factors that distinguished the high from the non-involved classes for the girls; and victimization by peers was the only factor distinguishing the victimized from the non-involved class for boys. These findings contribute to our understanding of the heterogeneity in physical dating violence victimization during adolescence and the malleable risk factors associated with each trajectory class for boys and girls.

Developmental trajectories of cigarette use and associations with multilayered risk factors among Chinese adolescents

INTRODUCTION

We aimed to identify developmental trajectories of cigarette use and risk factors associated with the distinct developmental courses of smoking in Chinese early adolescents from age 12 to 16 years.

METHODS

Analysis was conducted with secondary data from a longitudinal, prospective cohort of 3,521 Chinese adolescents randomly selected from 4 rural and 7 urban middle schools in Wuhan, China. A group-based growth mixture modeling approach was adopted to identify developmental trajectories of cigarette use. Multilayered intrapersonal (e.g., attitudes toward smoking) and interpersonal (e.g., parental smoking and perceived parental disapproval of smoking) risk factors selected from an ecological perspective were prospectively linked to the identified patterns of smoking trajectory.

RESULTS

Three trajectory patterns were identified from the whole cohort: nonsmokers (48.7%), stable light/occasional smokers (48.6%), and accelerating smokers (2.7%). After adjustments for gender, urban residence, and family socioeconomic status, adolescents with higher levels of problems in parent-child relationships and family disharmony, higher perceived norms of peer smoking, higher proportion of good friend smoking, having more troubles with teachers, poorer academic performance, and reporting more frequent depressive symptoms were significantly more likely to be in the trajectory group of either stable light/occasional smokers or accelerating smokers than in the group of nonsmokers. The probability of being in the accelerating smoking trajectory group was positively and significantly related to parental smoking and lack of school bonding.

CONCLUSIONS

Study findings help to advance knowledge of the distinct developmental courses of smoking behavior and their associations with multilayered risk factors among Chinese early adolescents.

A comparison of two models of Urgency: Urgency predicts both rash action and depression in youth

The aim of this study was to test two competing theories concerning the trait of urgency: (1) urgency reflects the tendency to act rashly/impulsively when emotional; or (2) urgency reflects a general reflexive responsivity to emotions that can lead either to rash action or ill-advised inaction, and thus to either impulsive behavior or depression. Following prior findings that 5^th grade urgency predicted 6^th grade impulsive behavior, we tested whether urgency also predicted 6^th grade depression (n = 1,906). After controlling for sex, early pubertal onset, 5^th grade depression, 5^th grade engagement in addictive behaviors, negative affect, positive affect, and other impulsivity-related traits, 5^th grade urgency level did predict higher levels of depression at the end of 6th grade. This finding is consistent with the view that urgency can lead either to rash action or ill-advised inaction. Urgency may be of transdiagnostic importance, contributing both to internalizing and externalizing dysfunction.

Smoking trajectories across high school: sensation seeking and Hookah use

INTRODUCTION

This study investigated the associations of trajectories of cigarette smoking over the high school years with the prior development of childhood sensation seeking and the subsequent use of cigarettes and hookah at age 20/21.

METHODS

Participants (N = 963) were members of a cohort-sequential longitudinal study, the Oregon Youth Substance Use Project. Sensation seeking was assessed across 4th-8th grades and cigarette smoking was assessed across 9th-12th grades. Cigarette and hookah use was assessed at age 20/21 for 684 of the 963 participants.

RESULTS

Four trajectory classes were identified: Stable High Smokers (6%), Rapid Escalators (8%), Experimenters (15%), and Stable Nonsmokers or very occasional smokers (71%). Membership in any smoker class versus nonsmokers was predicted by initial level and growth of sensation seeking. At age 20/21, there was a positive association between smoking and hookah use for Nonsmokers and Experimenters in high school, whereas this association was not significant for Stable High Smokers or Rapid Escalators.

CONCLUSIONS

Level and rate of growth of sensation seeking are risk factors for adolescent smoking during high school (Stable High Smokers, Rapid Escalators, and Experimenters), suggesting the need for interventions to reduce the rate of increase in childhood sensation seeking. For those who were not already established smokers by the end of high school, hookah use may have served as a gateway to smoking.

Factors Associated with Growth in Daily Smoking among Indigenous Adolescents

North American Indigenous adolescents smoke earlier, smoke more, and are more likely to become regular smokers as adults than youth from any other ethnic group yet we know very little about their early smoking trajectories. We use multilevel growth modeling across five waves of data from Indigenous adolescents (aged 10 to 13 years at Wave 1) to investigate factors associated with becoming a daily smoker. Several factors, including number of peers who smoked at Wave 1 and meeting diagnostic criteria for major depressive episode and conduct disorder were associated with early daily smoking. Only age and increases in the number of smoking peers were associated with increased odds of becoming a daily smoker.