Cohorts Of Boys Research Articles

A latent growth curve model to estimate electronic screen use patterns amongst adolescents aged 10 to 17\xa0years

BackgroundHigh quality, longitudinal data describing young people’s screen use across a number of distinct forms of screen activity is missing from the literature. This study tracked multiple screen use activities (passive screen use, gaming, social networking, web searching) amongst 10- to 17-year-old adolescents across 24 months.MethodsThis study tracked the screen use of 1948 Australian students in Grade 5 (n = 636), Grade 7 (n = 672), and Grade 9 (n = 640) for 24 months. At approximately six-month intervals, students reported their total screen time as well as time spent on social networking, passive screen use, gaming, and web use. Patterns of screen use were determined using latent growth curve modelling.ResultsIn the Grades 7 and 9 cohorts, girls generally reported more screen use than boys (by approximately one hour a day), though all cohorts of boys reported more gaming. The different forms of screen use were remarkably stable, though specific cohorts showed change for certain forms of screen activity.ConclusionThese results highlight the diverse nature of adolescent screen use and emphasise the need to consider both grade and sex in future research and policy.

Development of Catching by Children in Kindergarten to Grade 8: A Multicohort Longitudinal Study

The purpose of this study was to examine developmental change associated with catching by children in Grades Kindergarten through 8. Children's performance was tested on the Catching Subtest of the Ohio State University Scale of Intra Gross Motor Assessment (OSU-SIGMA). More precisely, four cohorts of boys and girls in Grades K-8 (N = 340) from 1992 to 2000: in 1992 Grades K-8, in 1994 Grades 2-8, in 1996 Grades 4-8, and in 1998 Grades 6-8. In 2000, the original Kindergarten cohort was tested again. Data, analyzed by hierarchical nonlinear modeling, yielded significant differences in mean initial status (intercept) of all three cohorts, in mean growth rate (slope) for the K-8 cohort only, in initial status of the K-8 cohort, and for participants in baseball and softball.

Gender differences in the causal relation between adolescents' maths self-concept and scholastic performance

Mathematics is a core subject in every school curriculum and it is strongly correlated with maths self-concept, which is defined as the subjective feelings and beliefs about one's competence in maths. In general, boys tend to report higher maths self-concept than girls, but the difference between boys and girls' maths scholastic performance is low or even inexistent. Some authors maintain that academic self-concept can play an important role as a motivational variable, promoting self-confidence and investment in the learning process. This study examined the causal relations between maths self-concept and maths scholastic performance in four cohorts of boys and girls within a three-wave longitudinal study. The first two cohorts were composed of 187 girls and 139 boys attending grades 7 and 8 at Time 1 and the third and fourth cohorts were composed of 167 girls and 123 boys attending grades 9 and 10 at Time 1. Structural Equation Modelling was used to test the fit of several models of causal relations. The results revealed that for the first two cohorts the best models were reciprocal and skill-development for both boys and girls. However, for the older students, a reciprocal model gave a best fit for the boys, but for the girls there was only one significant effect from maths self-concept to maths scholastic performance. Results are discussed on the basis of gender-related differential learning expectancies.

Autism spectrum disorder in Fragile X syndrome: Differential contribution of adaptive socialization and social withdrawal

The present study extends our previous work on characterizing the profile of social behavior abnormalities in boys with Fragile X (FraX) and autism spectrum disorder (ASD) using clinically oriented behavioral rating scales and standardized instruments. The goal was to further distinguish behavioral parameters contributing to the diagnostic classification of FraX + ASD. The study design included two cohorts of boys with FraX (3-8 years), a larger main cohort for cross-sectional analyses (n = 56, 24 with ASD), and a longitudinal subset (n = 30, 11 with ASD) of the main cohort with up to 3 yearly observations. The focus was on the relative contribution of delayed adaptive socialization and social withdrawal, including item components of their corresponding rating instruments, to the diagnosis of ASD in boys with FraX. Using a combination of regression analyses, we demonstrated that: (1) as delayed socialization, social withdrawal is also a correlate of FraX + ASD; (2) items of social withdrawal scales representing avoidance were the main predictors of ASD status, particularly in older boys; (3) adaptive socialization skills reflecting rules of social behavior and recognition and labeling of emotions, linked to verbal reasoning abilities, were selectively associated with FraX + ASD; (4) adaptive socialization is the primary determinant over time of ASD status in boys with FraX; and (5) integrated adaptive socialization-social withdrawal models allow the identification of distinctive FraX + ASD subgroups. Altogether, our findings suggest that two distinct but interrelated social behavior abnormalities, one linked to impaired cognitive processes (delayed socialization) and the second one to disturbance in limbic circuits (avoidance), play a role in the development of ASD in boys with FraX.

Committed and Reluctant Male Teenage Readers: Beyond Bedtime Stories

In this article we describe the leisure reading practices and attitudes towards reading of two cohorts of teenage boys and their parents from one educated, middle-class school community in Australia. Leisure reading refers to free choice or recreational reading across a range of genres (e.g., fiction/nonfiction) and modes (e.g., print/electronic). First we make explicit the cultural practices in one community that contributed to differential reading formations of boys who are capable readers, and second, we highlight the boys' increasing sense of agency and their selective appropriations of their families' leisure reading dispositions. In so doing, we respond to concerns raised in the research literature regarding the challenges educators and parents face in maintaining teenage boys' engagement in reading a wide range of texts. Drawing on a sociocultural perspective, we compare the patterns of reported leisure reading of teenage boys identified as “able and committed readers” with boys identified as “able and reluctant readers.” Using a model based on Rogoffs (1995) concept of guided participation, we compare the boys' attitudes towards various forms of reading and their parents' reports of family reading practices designed to guide boys into valued forms of leisure reading. We found that despite the similar ways in which both cohorts of boys had been supported as “cultural members” (Rogoff, Goncu, & Mosier, 1993) in developing valued reading practices in the home, the committed readers “took from” (Heath, 1983) their families' reading dispositions in very different ways than did the reluctant readers. A complex portrait of individual choice around reading emerges from our data. Our analytical model of guided participation provides a valuable framework for educators to examine the social formation of other sorts of readers across a range of cultural contexts.

Cortisol and Testosterone in Exercise at the Onset of Puberty in Boys

Previous studies have failed to demonstrate that aerobic exercises increase the adrenocortical activity in prepubescent boys. The purpose of the present study was to check this fact using a longitudinal approach. Two cohorts of boys participated in a one-year follow-up. The first cohort consisted of 14 boys at sexual maturation stage 1 (age 10 to 11 years) and the second cohort of 5 boys at stage 2 (age 12 years) at the onset of the observation. Boys performed 20-min aerobic exercise on a cycle ergometer at the beginning and end of the year of observation. Before and 5 min after the exercise, blood cortisol and testosterone were determined by radioimmunoassays. Before the onset of puberty (stage 1) cortisol increase during exercise was found in only 25% of boys. Exercise induced significant increase of cortisol level after achieving sexual maturation stage 2. Testosterone response was insignificant at the first three stages of sexual maturation.

Causes of juvenile obesity: Clues from epidemiology

A global epidemic of obesity is rapidly developing in children and adults, both in developed and developing countries. It is expected to create a huge public health problem in the future because of the conditions associated with obesity, both the immediate psychosocial and somatic problems and the longterm complications including glucose intolerance, type 2 diabetes, hypertension, hyperlipidaemia, and therefore an increased risk of cardiovascular diseases, increased risk of certain cancers and of gallstones, and eventually, excess mortality. It is commonly assumed that the causes of the epidemic is simple, namely both overeating and sedentary behavior, often in combination, and the preventive measures are all targeted to reverse this life style. When developed, obesity as such leads to overeating and physical inactivity for obvious reasons, but, unfortunately, it has not yet been possible to demonstrate that these behaviors precede the development of obesity. What are then the causes of obesity? Multiple family, twin and adoption studies leave no longer any doubt that obesity has a genetic predisposition that explains most if not all of the familial aggregation of obesity. Intensive search through the last 6 years has revealed some specific genes (e.g. leptin and the leptin receptor) that may cause obesity, but genetic variants that can account for the common obesity have not yet been identified. The development of obesity epidemic also shows that there in addition must be rapid environmental changes that may operate on the genetic background although clear gene‐environment interaction (synergism/antagonism) has not yet been found. We have conducted detailed analyses of very large population‐based Danish cohorts of boys in school age and young men examined as draftees, and we have have found that the obesity epidemic developed in two waves that appeared to be closely linked to birth cohorts and to be emerging already before school age: the first one during the 1940es and the second since mid 1960es. These findings strongly indicate that parallel preceding changes in the fetal or early childhood environment have played a role. To our great surprise, after having peaked among those born in the late 1980es, the prevalence of obesity in the young men is now rapidly declining again, further substantiating the role of rapidly altered environmental influences, the nature of which is unknown. Identification of the specific environmental factors may allow much more effective preventive measures to be taken in the future.

Longitudinal Patterns of Heart Rate and Fighting Behavior in 9− through 12-Year-Old Boys

To assess the temporal stability of heart rate and to examine its relationship with fighting behavior. Heart rate at ages 9 through 12 was compared to a composite measure of fighting behavior in three cohorts of low socioeconomic status boys (n = 138; two cohorts of boys who had been rated as having disruptive behavior problems in kindergarten and one normative cohort) while controlling for body size, pubertal status, and level of family adversity. Heart rate showed moderate stability at 1- and 2-year intervals in two of the three cohorts. The composite fighting score was related to heart rate for 11-year-old boys in the normative cohort and 12-year-old boys in one of the disruptive cohorts. These data support the conclusion that there is a relationship between heart rate and aggression even within a low socioeconomic status sample.

The Family Ecology of Boys' Peer Relations in Middle Childhood

The association between boys' peer relations, their antisocial behavior, academic skill deficit, and family ecology was examined with 2 cohorts of boys and their families (N = 206) who were interviewed, observed in the home, and assessed in school. Group comparisons revealed that rejected boys experienced poorer family management practices (i.e., monitoring and discipline practices), showed more family stress, were of lower socioeconomic status, and displayed more behavioral and academic problems than did their average peers. Correlational analyses provided similar results and showed good replication across the 2 cohorts. The hypothesis was tested that the effect of poor parent discipline on peer rejection was mediated by the boys' antisocial behavior and academic skill deficits. Structural equation analyses indicated that the mediated effect model provided a better fit to the data than did the direct effect model. The findings were discussed in relation to the need for longitudinally examining the role of parenting processes and child behavior in peer rejection at different points in development.

Social networks and aggressive behavior: Peer support or peer rejection?

Studied social networks and aggressive behavior in school in 2 cohorts of boys and girls in the 4th and 7th grades (N = 695). Measures of social networks yielded convergent findings. Highly aggressive subjects (both boys and girls) did not differ from matched control subjects in terms of social cluster membership or in being isolated or rejected within the social network. Peer cluster analysis and reciprocal best friend selections indicated that aggressive subjects tended to affiliate with aggressive peers. Even though highly aggressive children and adolescents were less popular than control subjects in the social network at large, they were equally often identified as being nuclear members of social clusters. Aggressive subjects did not differ from matched control subjects in the number of times they were named by peers as best friend, nor did the two groups differ in the probability of having friendship choices reciprocated by peers.

Child psychiatric sequelae of maternal war stress

Two cohorts of boys were examined while attending a well-baby clinic and reexamined at the end of the first grade of elementary school. One cohort (n = 57) consisted of boys born in the year of the Six-Day War in 1967. The other cohort was born 2 years later (n = 63). Data on socio-demographic background, early development, behavior at school and at home were obtained from the mothers and the teachers. Statistical analysis showed that the "war children" had significant developmental delays and regressive, non-affiliative and dissocial behavior. The children, who were in their first half year of life at the time of the war, were much more disturbed than those of whom the mothers were pregnant at the time of the war. The findings suggest that a disturbed mother-child relationship existed in the former group.

Analysis of cumulative caries prevalence in primary molars.

ABSTRACT Cumulative caries prevalences were estimated clinically in yearly cohorts of boys and girls, between 1 and 7 years of age, with at least 150 examinees in each cohort, and radiographically also from 4 years of age, in the occlusal, mesial, and distal surfaces of all four pairs of primary molars. Analysis of caries prevalence curves revealed best fit (based on least squares) with a transformed arc tan function with left end cut off, both for occlusal and for proximal surface caries. Compared with the exponential function, fit with the arc tan function was better in 19 out of a total of 24 comparisons. This difference was statistically significant in eight instances, but only in one instance of the reverse finding. By mathematical description of cumulative caries prevalence, no essential differences were revealed in the growth pattern of caries in occlusal and proximal surfaces of the primary molars. Implications of this finding are discussed.