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Background: We sought to determine if the rate of increase in body mass index (BMI) differs between first generation immigrant children (child and both parents born outside Canada); second generation immigrant children (child born in Canada with at least one parent born outside Canada); and native-born children (child and both parents born in Canada), and if the rate of increase varies across ethnic groups. Methods: Data were available from the evaluation of a 5-year heart health promotion program targeted to elementary school children from 24 schools in multi-ethnic, disadvantaged, inner-city neighborhoods in Montreal, Canada. Participants were 6392 children aged 9–12 years born in and outside of Canada. Height and weight were measured annually according to a standardized protocol. BMI increases with age were examined using individual growth models stratified by immigrant status grouping (first generation immigrant, second generation immigrant, native-born). Results: On average, BMI increased by 0.59, 0.73, and 0.82 kg/m2 with each year of age among first generation immigrant, second generation immigrant, and native-born children, respectively. These differences held across four family origin grouping (Europe, Asia, Central/South America, and Other). Conclusion: The protective effect of immigrant status on BMI increases with age dissipated in second generation immigrant children, whose rate of increase was similar to that of native-born children. Because immigrants constitute the fastest growing segment of the Canadian population, it is important to understand the causes of the higher BMI increases with successive generations. [ABSTRACT FROM AUTHOR]

Purpose: To study the effect of cigarette use on height and adiposity in adolescents. Methods: Data on cigarette use were collected every 3 months for 5 years from adolescents initially 12–13 years of age. Height, weight, and triceps skinfold thickness were measured in survey cycles 1, 12, and 19. Multivariate linear regression models were fitted to estimate the association between cigarette use and the anthropometric measures in a dataset that pooled data over two time periods, from survey cycles 1–12 and from survey cycles 12–19. Results: Data were available for 451 boys and 478 girls. Seven percent of boys and 14% of girls smoked ≥30 cigarettes per month on average during the first time period; 9% of boys and 18% of girls smoked ≥30 cigarettes per month on average during the second time period. In boys, a 100-cigarette per month increment in cigarette use over the preceding 2.5 years was independently associated with lower body mass index (−0.4 kg/m2) and shorter height (−0.7 cm). In girls, cigarette use was not associated with height or adiposity. Conclusions: While there was no relation in girls, cigarette use appears to decrease body mass index and height in boys. Young girls may be less likely to take up cigarette smoking if tobacco control messages emphasize that cigarette use may not be associated with reduced weight in adolescent females. [Copyright &y& Elsevier]

Purpose: To describe longitudinal trajectories of smoking intensity in adolescent novice smokers and to identify predictors of trajectory class membership. Methods: Cigarette consumption among 369 novice smokers (mean age 13 years) was measured over a mean 24 months of follow-up after smoking onset. Classes of smoking intensity trajectories were identified using latent class growth modeling. Predictors of trajectory class membership were identified in polytomous logistic regression. Results: There was considerable between-subject heterogeneity in individual trajectories over time. Four classes of smoking intensity trajectories were identified: low-intensity, non-progressing smokers (72.4% of subjects), and slow, moderate, and rapid escalators (11.1%, 10.8%, and 5.7% of subjects, respectively). Gender, poor academic performance, and having more than half of friends who smoke at smoking onset independently predicted development of trajectory pattern. Escalating trajectory patterns were associated with earlier development of nicotine dependence and tolerance. Conclusions: Cigarette consumption will not escalate rapidly among three-quarters of adolescent novice smokers. Novice smokers who do escalate rapidly should be targeted for early tobacco control intervention to prevent development of nicotine dependence and sustained smoking. [Copyright &y& Elsevier]

PURPOSE: To examine the test retest reliability, internal consistency, and convergent construct validity of selected measures of nicotine dependence (ND) among adolescents.METHODS: Self-reports of sociodemographic characteristics and smoking behavior were collected in a convenience sample of 238 high school students aged 13 to 19 years. ND was measured in the Hooked on Nicotine Checklist (HONC), the Stanford Dependence Index (SDI) and in 45 new items identified in consultation with experts and focus group interviews with adolescent smokers.RESULTS: Test retest reliability among past 3-month smokers indicated good to excellent reliability coefficients for HONC items (κ 0.61 to 0.93), except one item that tapped feelings of depression on withdrawal (κ = 0.34). Intraclass correlation coefficients for SDI items ranged from 0.71 to 0.77. Test retest reliability coefficients for the 45 new items ranged from 0.20 to 0.90. The HONC and SDI demonstrated good internal consistency (Cronbach''s α = 0.90 and 0.78, respectively). Convergent construct validity against cigarette exposure was demonstrated for the HONC, SDI, and most of the 45 new items.CONCLUSIONS: The HONC and SDI demonstrated excellent and good psychometric properties, respectively. Most of the 45 new items hold promise as indicators of ND in youth, and should be further investigated. [Copyright &y& Elsevier]

Purpose: To study the effect of maternal psychiatric disorders (depression, anxiety disorder, bipolar disease, schizophrenia, unspecified psychiatric disorder, and comorbid conditions) and odds of preterm birth.Methods: The Consortium on Safe Labor (2002-2008), an observational cohort with 12 centers from across the United States included 223,394 singleton pregnancies with clinical data obtained from electronic medical records and maternal diagnoses of psychiatric disorders from maternal discharge summaries. Length of gestation was based on the best clinical estimate and categorized as birth less than 39, less than 37, less than 34, and less than 28 weeks' gestation. The adjusted odds ratios (ORs) with 95% confidence intervals of birth were estimated by logistic regression with generalized estimating equations.Results: Any maternal psychiatric disorder was associated with odds of birth less than 39 weeks' gestation (odds ratio [OR] = 1.32, 95% confidence interval = 1.28-1.37), less than 37 weeks' gestation (OR = 1.45, 1.38-1.52), less than 34 weeks' gestation (OR = 1.47, 1.35-1.59), and less than 28 weeks' gestation (OR = 1.57, 1.36-1.82). Specifically, odds of birth less than 37 weeks' gestation were associated with maternal depression (OR = 1.31, 1.23-1.40), anxiety disorder (OR = 1.68, 1.41-2.01), depression with anxiety disorder (OR = 2.31, 1.93-2.78), bipolar disease (OR = 1.54, 1.22-1.94), bipolar disease with depression and/or anxiety disorder (OR = 1.70, 1.30-2.22), and unspecified psychiatric disorder (OR = 1.52, 1.41-1.64).Conclusions: Maternal psychiatric disorders, especially comorbid psychiatric conditions, were associated with increased likelihood of preterm birth. [ABSTRACT FROM AUTHOR]

Purpose: To assess whether a child’s age relative to the median age of classmates in the same grade is associated with the onset of gambling. Methods: Grade 7 students (n = 647) from 10 Montreal secondary schools were followed for 8 years. Relative age was expressed as years above or below the school-specific grade 7 median age. Hazard ratios and 95% confidence intervals (CI) were estimated for the association between relative age and age of gambling onset, with adjustment for sex, ethnicity, parent education, and impulsivity. Results: A greater proportion of students in the youngest quartile gambled compared with the oldest (85.8% vs 74.7%). Hazards of gambling onset for students younger than the median age were elevated after age 10.5 years, but hazards were protective beforehand. At age 17 years, for example, the hazard for gambling onset was 61% greater (95% CI 1.4–1.9) for youth who were 1 year younger, but at age 8 years the hazard was 23% lower (95% CI 0.7–0.9). Conclusions: Younger relative age may be a risk factor for gambling onset in older youth. [Copyright &y& Elsevier]

Purpose: Little is known about how seasonal variation in physical activity relates to declining physical activity in adolescence. We quantified how each of daily weather conditions and season affect physical activity during adolescence. Methods: We followed 1293 students, initially aged 12 to 13 years over 5 years. Participants completed a 7-day physical activity recall checklist every 3 months. Data on daily weather conditions were obtained from Environment Canada. The association between the number of physical activity sessions per day, and each of season, and daily weather conditions was assessed in Poisson regressions. Results: Adjusting for age, sex, and month, the average number of physical activity sessions per day was 2% to 4% lower for every 10mm of rainfall and 1% to 2% higher for every 10°C increase in temperature. Although every 10cm of snow accumulation was associated with 5% higher activity rates, days with snowfall had lower physical activity. Physical activity was lower during winter and increased during warmer months. However, the warm-month increases did not compensate for winter decreases so that activity decreased by 7% yearly. Conclusions: Declines in physical activity during adolescence may be partly explained by declines during winter. Increasing opportunities for physical activity during poor weather, in particular during winter, may mitigate declines in physical activity during adolescence. [Copyright &y& Elsevier]

Abstract: Purpose: Findings from prospective studies on associations between physical activity and adiposity among youth are inconsistent. Our aim was to describe physical activity trajectories during secondary school and examine the association with change in adiposity in youth. Methods: Physical activity was measured in 20 survey cycles from 1999 to 2005; anthropometrics were measured in survey cycles 1, 12, and 19. Individual growth curves modeling moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) were estimated. Estimates of initial level and rate of decline in MVPA and VPA bouts per week were included as potential predictors of body fat% and body mass index using age- and sex-specific linear regression. Results: Complete data were available for 840 and 760 adolescents aged 12–13 years at baseline, followed from survey cycles 1–12 and 12–19, respectively. Among girls, yearly declines of one MVPA and one VPA bout per week during earlier adolescence were associated with increases of 0.19 (95% confidence interval [CI], 0.02–0.36) and 0.47 (95% CI, 0.015–0.92) units of body fat%, respectively. In boys, a yearly decline of one MVPA bout per week was associated with an increase of 0.38 (95% CI, 0.05–0.70) units of body fat% during later adolescence. Conclusions: Obesity prevention programs should include strategies to prevent declines in physical activity. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Purpose: To examine the test retest reliability, internal consistency, and convergent construct validity of selected measures of nicotine dependence (ND) among adolescents.Methods: Self-reports of sociodemographic characteristics and smoking behavior were collected in a convenience sample of 238 high school students aged 13 to 19 years. ND was measured in the Hooked on Nicotine Checklist (HONC), the Stanford Dependence Index (SDI) and in 45 new items identified in consultation with experts and focus group interviews with adolescent smokers.Results: Test retest reliability among past 3-month smokers indicated good to excellent reliability coefficients for HONC items (kappa 0.61 to 0.93), except one item that tapped feelings of depression on withdrawal (kappa = 0.34). Intraclass correlation coefficients for SDI items ranged from 0.71 to 0.77. Test retest reliability coefficients for the 45 new items ranged from 0.20 to 0.90. The HONC and SDI demonstrated good internal consistency (Cronbach's alpha = 0.90 and 0.78, respectively). Convergent construct validity against cigarette exposure was demonstrated for the HONC, SDI, and most of the 45 new items.Conclusions: The HONC and SDI demonstrated excellent and good psychometric properties, respectively. Most of the 45 new items hold promise as indicators of ND in youth, and should be further investigated. [ABSTRACT FROM AUTHOR]