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Background: There is evidence that mental health problems are increasing and substance use behaviours are decreasing. This paper aimed to investigate recent trends in mental ill health and health-related behaviours in two cohorts of UK adolescents in 2005 and 2015.Methods: Prevalences in mental health (depressive symptoms, self-harm, anti-social behaviours, parent-reported difficulties) and health-related behaviours (substance use, weight, weight perception, sleep, sexual intercourse) were examined at age 14 in two UK birth cohorts; Avon Longitudinal Study of Parents and Children (ALSPAC, N = 5627, born 1991-92) and Millennium Cohort Study (MCS, N = 11 318, born 2000-02). Prevalences and trend estimates are presented unadjusted and using propensity score matching and entropy balancing to account for differences between samples.Results: Depressive symptoms (9% to 14.8%) and self-harm (11.8% to 14.4%) were higher in 2015 compared with 2005. Parent-reported emotional difficulties, conduct problems, hyperactivity and peer problems were higher in 2015 compared with 2005 (5.7-8.9% to 9.7-17.7%). Conversely, substance use (tried smoking, 9.2% to 2.9%; tried alcohol, 52.1% to 43.5%, cannabis, 4.6% to 3.9%), sexual activity (2% to 0.9%) and anti-social behaviours (6.2-40.1% to 1.6-27.7%) were less common or no different. Adolescents in 2015 were spending less time sleeping (<8 h 5.7% to 11.5%), had higher body mass index (BMI) (obese, 3.8% to 7.3%) and a greater proportion perceived themselves as overweight (26.5% to 32.9%). The findings should be interpreted bearing in mind limitations in ability to adequately harmonize certain variables and account for differences in attrition rates and generalizability of the two cohorts.Conclusions: Given health-related behaviours are often cited as risk factors for poor mental health, our findings suggest relationships between these factors might be more complex and dynamic in nature than currently understood. Substantial increases in mental health difficulties, BMI and poor sleep-related behaviours highlight an increasing public health challenge. [ABSTRACT FROM AUTHOR]

Background: Epidemiologists are often interested in examining different hypotheses for how exposures measured repeatedly over the life course relate to later-life outcomes. A structured approach for selecting the hypotheses most supported by theory and observed data has been developed for binary exposures. The aim of this paper is to extend this to include continuous exposures and allow for confounding and missing data.Methods: We studied two examples, the association between: (i) maternal weight during pregnancy and birthweight; and (ii) stressful family events throughout childhood and depression in adolescence. In each example we considered several plausible hypotheses including accumulation, critical periods, sensitive periods, change and effect modification. We used least angle regression to select the hypothesis that explained the most variation in the outcome, demonstrating appropriate methods for adjusting for confounders and dealing with missing data.Results: The structured approach identified a combination of sensitive periods: pre-pregnancy weight, and gestational weight gain 0-20 weeks and 20-40 weeks, as the best explanation for variation in birthweight after adjusting for maternal height. A sensitive period hypothesis best explained variation in adolescent depression, with the association strengthening with the proximity of stressful family events. For each example, these models have theoretical support at least as strong as any competing hypothesis.Conclusions: We have extended the structured approach to incorporate continuous exposures, confounding and missing data. This approach can be used in either an exploratory or a confirmatory setting. The interpretation, plausibility and consistency with causal assumptions should all be considered when proposing and choosing life course hypotheses. [ABSTRACT FROM AUTHOR]

Background The prevalence of obesity has increased rapidly in most developed countries in the last decades, and this rise is now spreading to developing countries. Childhood obesity is also increasing. The UK government has set a target to halt the rise in childhood obesity by 2010. Dietary recommendations are a central component of any comprehensive weight-loss programme. A low-fat energy-restricted diet is the conventional therapy for obesity, but alternative dietary interventions have been proposed in recent years. [ABSTRACT FROM PUBLISHER]

Background: Previous research has documented that children conceived through medically assisted reproduction (MAR) are at increased risk of poor birth outcomes, such as low birthweight (LBW), which are risk factors for stunted longer-term cognitive development. However, parents who undergo MAR to conceive have, on average, advantaged socioeconomic backgrounds which could compensate for the negative effects of being born LBW. Previous studies have not analysed whether the negative effects of LBW are attenuated among MAR conceived children.Methods: We draw on the UK Millennium Cohort Study (sweeps 1-6) which contains a sub-sample of (N = 396) MAR-conceived children. The dependent variable measures cognitive ability at around ages 3, 5, 7, 11 and 14. We examine the cognitive development of four groups of children: MAR-conceived low birthweight (MAR LBW); MAR-conceived non-low birthweight (MAR NLBW); naturally conceived low birthweight (NC LBW); naturally conceived non-low birthweight (NC NLBW). We estimate the two following linear regression models for each sweep: (i) a baseline model to examine the unadjusted association between cognitive development and low birthweight by mode of conception; and (ii) a model adjusted by socio-demographic family characteristics.Results: In baseline models, MAR LBW children [age 3: β  =  0.021, 95% confidence interval (CI): -0.198, 0.241; age 5: β  =  0.21, 95% CI: 0.009, 0.418; age 7: β  =  0.163, 95% CI: -0.148, 0.474; age 11: β  =  0.003, 95% CI: -0.318, 0.325; age 14: β  =  0.156, 95% CI: -0.205, 0.517], on average perform similarly in cognitive ability relative to NC NLBW at all ages, and display higher cognitive scores than NC LBW children until age 7. When we account for family characteristics, differences are largely attenuated and become close to zero at age 14.Conclusions: Despite the higher incidence of LBW among MAR compared with NC children, they do not seem to experience any disadvantage in their cognitive development compared with naturally conceived children. This finding is likely explained by the fact that, on average, MAR children are born to socioeconomically advantaged parents. [ABSTRACT FROM AUTHOR]

Background: Disability among adolescents is associated with both poorer mental health (MH) and higher levels of bullying-victimization. Bullying, therefore, conceivably mediates the association between disability and MH. Quantifying this pathway is challenging as the exposure (disability), mediator (bullying) and outcome (MH) are subjective, and subject to dependent measurement error if the same respondent reports on two or more variables.Methods: Utilizing the counterfactual and potential outcomes approaches to causal mediation, we decomposed the total effect of disability on MH into natural indirect effects (through bullying) and natural direct effects (not through bullying) using a sample of 3409 adolescents. As the study included data from multiple informants (teacher, parent, adolescent) on the outcome (MH, as measured on the Strengths and Difficulties Questionnaire) and two informants (adolescent, parent) on the mediator (bullying), we assessed the influence of dependent measurement error.Results: For preferred analysis (using parent-reported bullying and adolescent-reported MH), the total effect was a 2.18 [95% confidence interval (CI): 0.66-3.40] lower MH score for adolescents with a disability, compared with those with no disability (strength of association equivalent to 37% of the standard deviation for MH). Bullying explained 46% of the total effect. Use of adolescent-reported bullying with adolescent-reported MH produced similar results (37% mediation, 95% CI: 12-74%).Conclusions: Disability exerts a detrimental effect on adolescent MH, and a large proportion of this appears to operate through bullying. This finding does not appear to be spurious due to dependent measurement error. [ABSTRACT FROM AUTHOR]

Background: Sexual activity may be less likely to occur during periods of school enrolment because of the structured and supervised environment provided, the education obtained and the safer peer networks encountered while enrolled. We examined whether school enrolment was associated with teen pregnancy in South Africa. Methods: Using longitudinal demographic surveillance data from the rural Agincourt sub-district, we reconstructed the school enrolment status from 2000 through 2011 for 15 457 young women aged 12-18 years and linked them to the estimated conception date for each pregnancy during this time. We examined the effect of time-varying school enrolment on teen pregnancy using a Cox proportional hazard model, adjusting for: age; calendar year; household socioeconomic status; household size; and gender, educational attainment and employment of household head. A secondary analysis compared the incidence of pregnancy among school enrolees by calendar time: school term vs school holiday. Results: School enrolment was associated with lower teen pregnancy rates [adjusted hazard ratio (95% confidence interval): 0.57 (0.50, 0.65)].This association was robust to potential misclassification of school enrolment. For those enrolled in school, pregnancy occurred less commonly during school term than during school holidays [incidence rate ratio (95% confidence interval): 0.90 (0.78, 1.04)]. Conclusions: Young women who drop out of school may be at higher risk for teen pregnancy and could likely benefit from receipt of accessible and high quality sexual health services. Preventive interventions designed to keep young women in school or addressing the underlying causes of dropout may also help reduce the incidence of teen pregnancy. [ABSTRACT FROM AUTHOR]

Objectives Several studies have shown a relation between smoking and suicide. It is not clear if this relation should be considered causal, or if other risk factors for suicide, left unmeasured in many studies, might explain the smoking-suicide association. The aim of this cohort study was to analyse the role of smoking and other potential risk factors measured in adolescence on subsequent suicide. Methods Information on smoking, and other potential risk factors from childhood and adolescence was collected among 49 323 men, born 1949-1951, at conscription for compulsory military training in the years 1969-1970. Mortality data were obtained from the Swedish cause of death register for the years 1971-1996. Results There was a clear trend of increasing suicide risk with increasing intensity of smoking reported at conscription. Those smoking >20 cigarettes/day had a strongly increased relative risk of suicide (OR = 3.03, 95% CI: 1.72, 5.34) during the first 13 years of follow-up. From 14 to 26 years after conscription, the risk was only slightly weaker (OR = 2.53, 95% CI: 1.36, 4.72). When we adjusted for other risk factors for suicide measured at the conscription examination (psychiatric diagnosis, parental divorce, low emotional control, medication for nervous problems, contact with police and childcare, heavy alcohol consumption, drug use, and education) in a multivariate analysis, the trend with smoking intensity disappeared, and there was no longer an increased relative risk for the heavy smokers (follow-up years 1-13: OR = 0.98, 95% CI: 0.53, 1.82; years 14-26: OR = 1.31, 95% CI: 0.91, 1.87). Conclusion The increased risk of suicide among smokers was almost entirely explained by an increased prevalence of heavy alcohol consumption and low mental well-being among smokers. That is, the association between smoking and suicide is probably due to confounding by these other factors. These results do not support the hypothesis that tobacco consumption itself is a risk factor for suicide. [ABSTRACT FROM AUTHOR]

Background: To determine whether there are inequalities in the incidence of fatal and non-fatal unintentional injuries among Jewish and Arab children in Israel.Methods: A nationwide random sample of injured children aged 0-17 attending emergency rooms (ER) during one year was selected (n = 11 058). The number of cases was weighted to 365 days and rates and odds ratios (OR) were calculated. Logistic regression was performed to study the OR of hospitalization in the total population and among Jews and Arabs controlling for independent variables.Results: The incidence of ER admissions among the Jews was 752.6/10 000 (95% CI: 738.1-767.1), 1.5 times higher than among the Arabs (492.8/10 000, 95% CI: 472.8-512.8). However, the rate of hospitalization was 1.1 times higher among Arabs than among Jews and the mortality rate was 3.2 times higher among Arabs than among Jews.Conclusions: The differences in injury rates for fatal and non-fatal injuries may be due to differences in the severity of injuries or in the use of services by the two populations. A study is underway to elucidate this point. [ABSTRACT FROM AUTHOR]