Maternal smoking during pregnancy and scholastic achievement in childhood: evidence from the LIFECOURSE cohort study.

Background: Research on the impact of maternal smoking during pregnancy (MSDP) on scholastic achievement in the offspring has shown conflicting findings. The objective of this study was to assess the impact of MSDP on scholastic achievement in a birth cohort of children in 4th, 7th and 10th grades. Methods: We analysed data from the LIFECOURSE study, a cohort study of risk and protective factors in all children born in Reykjavik, Iceland, in the year 2000 (N = 1151, girls = 49.3%). Retrospective registry data for 2014-2015 were merged with prospective survey data that were collected in April 2016. Data on MSDP were assessed during regular antenatal visits at the end of the first trimester. Standardized academic achievement scores were obtained from official school transcripts. Data were analysed using OLS regressions that were entered in three hierarchical blocks. Results: Children of mothers who smoked tobacco during the first trimester consistently revealed between 5% and 7% lower scores on standardized academic achievement in 4th, 7th and 10th grade (∼6-8 points on a normally distributed 120 point scale) than those of mothers who had not smoked tobacco during this period (P < 0.05). These findings held after controlling for several factors associated with the time of birth (e.g. birth weight, maternal age at birth, birth order, parental cohabitation and household income), as well as the year of scholastic assessment (parental cohabitation, household income and parental education). Conclusions: Maternal smoking during pregnancy was negatively related to scholastic achievement in the offspring during 4th, 7th and 10th grade.

The increase in symptoms of anxiety and depressed mood among Icelandic adolescents: time trend between 2006 and 2016.

Background: Both research and popular media reports suggest that adolescent mental health has been deteriorating across societies with advanced economies. This study sought to describe the trends in self-reported symptoms of depressed mood and anxiety among Icelandic adolescents. Methods: Data for this study come from repeated, cross-sectional, population-based school surveys of 43 482 Icelandic adolescents in 9th and 10th grade, with six waves of pooled data from 2006 to 2016. We used analysis of variance, linear regression and binomial logistic regression to examine trends in symptom scores of anxiety and depressed mood over time. Gender differences in trends of high symptoms were also tested for interactions. Results: Linear regression analysis showed a significant linear increase over the course of the study period in mean symptoms of anxiety and depressed mood for girls only; however, symptoms of anxiety among boys decreased. The proportion of adolescents reporting high depressive symptoms increased by 1.6% for boys and 6.8% for girls; the proportion of those reporting high anxiety symptoms increased by 1.3% for boys and 8.6% for girls. Over the study period, the odds for reporting high depressive symptoms and high anxiety symptoms were significantly higher for both genders. Girls were more likely to report high symptoms of anxiety and depressed mood than boys. Conclusions: Self-reported symptoms of anxiety and depressed mood have increased over time among Icelandic adolescents. Our findings suggest that future research needs to look beyond mean changes and examine the trends among those adolescents who report high symptoms of emotional distress.

Secular trends in overweight and obesity among Icelandic adolescents: do parental education levels and family structure play a part?

AIMS: To investigate whether the secular trend in the increasing prevalence of overweight and obesity among 16- to 20-year-old adolescents in Iceland varied by levels of parental education and family structure. METHODS: Odds ratios were calculated from repeated population-based, cross-sectional surveys comprising cohorts of 16- to 20-year-old Icelandic adolescents attending junior colleges in 1992 (n=4,922), 2004 (n=11,031), 2007 (n=11,229), and 2010 (n=11,388). Body mass index (BMI) was calculated from self-reported weight and height and categorised as normal weight or overweight and obese, and examined in relation to parental education level and family structure. RESULTS: The odds of being overweight increased by 2.62 and 1.71 for boys and girls respectively over each of the survey time points. The prevalence of overweight and obesity increased across all three subgroups (low, medium, and high) of parental education level. The probability of overweight across all years were consistently the highest for youths with parents in the low-education category followed by middle-educated and high-educated parental background (p<0.05). The gap in overweight and obesity trends between respondents' parental education backgrounds increased over time and was generally explained more by the fathers' education than by the mothers' education (p<0.05). Family structure was not associated with the prevalence of overweight and obesity in our data. CONCLUSIONS: Differences in parental levels of education are associated with accelerating trends in prevalence of overweight and obesity among 16- to 20-year-old adolescents in Iceland.

Trends in body mass index among Icelandic adolescents and young adults from 1992 to 2007.

Trends in body mass index (BMI) among 51,889 14- to 20-year-old Icelandic adolescents and young adults were examined using data from cross-sectional population surveys conducted from 1992 to 2007. Prevalence of overweight increased for both genders in all age groups, except for 14- and 20-year-old girls. Obesity prevalence increased among boys in all age groups, except for 16-year-olds, and among 15- and 20-year-old girls. The largest increase in obesity rates among both genders was found in the oldest age group. Moreover, not only has the prevalence of obesity increased, but also the extent of obesity has grown more severe among 15- and 17-year-olds boys and among girls in the oldest age group.

The neighborhood effects of disrupted family processes on adolescent substance use.

In the current paper, we argue that the neighborhood-level of disrupted family processes (weak social ties to parents and coercive family interaction) should have a contextual effect on adolescent substance use (cigarette smoking, heavy drinking, and lifetime cannabis use), because adolescents living in neighborhoods in which disrupted family processes are prevalent should be more likely to associate with deviant (substance using) peers. We use nested data on 5491 Icelandic adolescents aged 15 and 16 years in 83 neighborhoods to examine the neighborhood-contextual effects of disrupted family processes on adolescent substance use (cigarette smoking, heavy drinking, and lifetime cannabis use), that is, whether neighborhoods in which disrupted family processes are common have more adolescent substance use, even after partialling out the individual-level effects of disrupted family processes on substance use. As predicted, we find that the neighborhood-levels of disrupted family processes have significant, contextual effects on all the indicators of substance use, and that association with substance using peers mediates a part of these contextual effects. The findings illustrate the limitation of an individual-level approach to adolescent substance use.

The spreading of suicidal behavior: The contextual effect of community household poverty on adolescent suicidal behavior and the mediating role of suicide suggestion.

Despite the longstanding interest of social researchers in the social factors that influence suicide and suicidal behavior, multilevel research on this topic has been limited. Using nested survey data on 5331 Icelandic adolescents (born in 1990 and 1991) in 83 school-communities, the current study examines the contextual effect of community household poverty on adolescent suicidal behavior (suicide ideation and suicide attempt). The findings show that the concentration of household poverty in the school-community has a significant, contextual effect on adolescent suicidal behavior. Furthermore, we test an "epidemic" explanation for this effect, examining the mediating role of suicide suggestion (contact with suicidal others). We find that suicide suggestion mediates a substantial part of the contextual effect of community household poverty on suicide attempt, while mediation is modest in the case of suicide ideation. The findings indicate that community household poverty increases the risk of adolescent suicidal behavior in part because communities in which household poverty is common entail a higher risk for adolescents of associating with suicidal others. The study demonstrates how the concentration of individual problems can have macrolevel implications, creating social mechanisms that cannot be reduced to the circumstances or characteristics of individuals.

Trends in depressive symptoms, anxiety symptoms and visits to healthcare specialists: a national study among Icelandic adolescents.

AIMS: The aim of the study was to examine trends in adolescent depression and anxiety symptoms from 1997 to 2006, using four time-points (1997, 2000, 2003, and 2006), and adolescent mental health service use in the same period, using three time-points (1997, 2000, and 2006). METHODS: Four cross-sectional population-based samples of 14- and 15-year-old students, attending the compulsory 9th and 10th grades of the Icelandic secondary school system, completed questionnaires relating to mental health. In total, 21,245 students participated in the four studies. RESULTS: Anxiety symptoms increased significantly for both boys and girls, throughout the period from 1997 to 2006. Depressive symptoms increased significantly for girls, while there were no significant changes in depression among boys. During the same time period, the proportion of adolescents who visited healthcare specialists, i.e. psychiatrists, psychologists and social workers, increased significantly. The results revealed that regular visits (six times or more during 1 year) to psychiatrists and psychologists increased significantly over the same period among girls but not among boys. CONCLUSIONS: The findings show that symptoms of depression and anxiety have increased among adolescents in Iceland. Future work would benefit from further research into the trends in risk and protective factors associated with these outcomes. The findings call particular attention to the increasing risk for depression and anxiety symptoms among girls.

Trends in prevalence of substance use among Icelandic adolescents, 1995-2006.

BACKGROUND: Adolescent substance use continues to be of great global public health concern in many countries with advanced economies. Previous research has shown that substance use among 15-16 year-old-youth has increased in many European countries in recent years. The aim of this study was to examine trends in prevalence of daily smoking, alcohol intoxication, and illicit substance use among Icelandic adolescents. METHODS: Repeated-measures, population-based cross-sectional surveys of between 3,100 and 3,900 10th-grade students who participated in the annual Youth of Iceland studies were analyzed, with response rates of between 80% and 90%. RESULTS: The prevalence of daily smoking, alcohol intoxication, and illicit substance use was at a peak in 1998, with almost 23% having reported daily smoking, 42% having reported becoming intoxicated at least once during the last 30 days, and over 17% having used hashish once or more often in their lifetime. By 2006, daily smoking had declined to 12%, having become intoxicated once or more often during the last 30 days to 25%, and having ever used hashish declined to 9%. CONCLUSION: The prevalence of substance use among Icelandic 10th graders declined substantially from 1995 to 2006. Proportions of adolescents who smoke cigarettes, had become intoxicated during the last 30 days, as well as those admitting to hashish use all decreased to a great deal during the period under study. The decline in prevalence of adolescent substance use in Iceland is plausibly the result of local community collaboration where researchers, policy makers and practitioners who work with young people have combined their efforts.

Social correlates of cigarette smoking among Icelandic adolescents: a population-based cross-sectional study.

BACKGROUND: Previous research has shown that between 80 and 90 percent of adult smokers report having started smoking before 18 years of age. Several studies have revealed that multiple social factors influence the likelihood of smoking during adolescence, the period during which the onset of smoking usually occurs. To better understand the social mechanisms that influence adolescent smoking, we analyzed the relationship and relative importance of a broad spectrum of social variables in adolescent smoking in Iceland, a Nordic country with high per-capita income. METHODS: We used cross-sectional data from 7,430 14- to 16 year-old students (approximately 81% of all Icelanders in these age cohorts) in the 2006 Youth in Iceland study. The Youth in Iceland studies are designed to investigate the role of several cognitive, behavioral, and social factors in the lives of adolescents, and the data collected are used to inform the design, implementation, and evaluation of substance use prevention programs that are being developed by Icelandic social scientists, policy makers, and practitioners. RESULTS: Our analysis revealed that friends' smoking behavior and attitude toward smoking were strongly associated with adolescent smoking and other tobacco use, as well as alcohol consumption during the previous 30 days. Main protective factors were parent's perceived attitude toward smoking, the quantity of time spent with parents, absence of serious verbal conflict between parents and adolescents, and participation in physical activity. Family structure was related to adolescent smoking to a small extent, but other background factors were not. CONCLUSION: We conclude that multiple social factors are related to adolescent smoking. Parents and other primary preventive agents need to be informed about the complicated nature of the adolescent social world in order to maximize their impact.

Trends in physical activity and participation in sports clubs among Icelandic adolescents.

BACKGROUND: Physical activity among adolescents and its implications for health status is of increasing concern. We examined trends in physical activity and participation in sports clubs among Icelandic adolescents. METHODS: Cross-sectional survey data were used to determine levels of vigorous physical activity and participation in sports clubs (defined as engaging in moderately intensive activity four times or more a week) for cohorts of Icelandic adolescents in 1992, 1997, 2000 and 2006. RESULTS: There was a 6% increase in the rate of vigorous physical activity and a 15% increase in active sports club participation among 14- and 15-year old Icelandic adolescents from 1992 to 2006. The trends were consistent across genders; however, only 53% of boys actually achieved the recommended criterion for vigorous physical activity, with the percentage of girls averaging 16% lower than that for boys. Additionally, there was an overall increase in the proportion of inactive adolescents, with girls consistently reporting higher levels of inactivity than boys even though the net increase in inactivity was higher for boys. CONCLUSION: Although our results show an overall increase in vigorous physical activity and participation in sports clubs over the past decade among both genders, our data also indicate that over half of all Icelandic adolescents are not achieving the recommended level of participation in physical activity. Furthermore, less than one third of the population studied is achieving the recommended level of activity through organized clubs. Initiatives to increase physical activity among the least active of adolescents should receive high priority in public health.