Stability of adolescent body mass index during three years of follow-up

Mexican American adolescents' sleep patterns: contextual correlates and implications for health and adjustment in young adulthood

Late adolescence is a period of substantial risk for unhealthy sleep patterns. This study investigated the contextual correlates and health and adjustment implications of sleep patterns among Mexican American youth (N = 246; 51% female). We focused on Mexican American youth because they represent a large and rapidly increasing subgroup of the US population that is at higher risk for health and adjustment problems; this higher risk may be explained, in part, by sleep patterns. Using data from seven phone diary interviews conducted when youth averaged 18 years of age, we assessed average nighttime sleep duration and night-to-night variability in sleep duration. Guided by socio-ecological models, we first examined how experiences in the family context (time spent and quality of relationships with parents, parents' familism values) and in extra-familial contexts (school, work, peers) were related to sleep duration and variability. The findings revealed that time spent in school, work, and with peers linked to less sleep. Further, conflict with mothers was related to greater sleep variability. Next, we tested the implications of sleep in late adolescence for health (perceived physical health, body mass index) and adjustment (depressive symptoms, risky behaviors) in young adulthood. These findings indicated that more sleep variability predicted relative decreases in health and increases in risky behaviors, and shorter sleep duration predicted relative decreases in poorer perceived health for males. The discussion highlights the significance of the transition to young adulthood as a target for sleep research and the importance of studying sleep within its socio-cultural context.

Tracking of weight status and body fatness in Italian children

The prevalence of weight disorders among school-aged children is an increasing phenomenon and it is of great importance to identify the characteristics of individuals at risk of gaining or retaining weight. This study aimed to examine the prevalence of weight disorders and their tracking over a 3-year period in a sample of Italian children. Body mass, body height and selected skinfold thicknesses were assessed in 355 children at the age of 7 and 10 years. Tracking of body mass index (BMI), inverted BMI (iBMI) and skinfold-based body fat were analyzed and the relationships between changes in BMI and body fat were examined. Children presenting with overweight or obesity at 7 years old showed a trend toward lower weight categories at 10 years old. Conversely, a trend to become overweight was observed among normal weight boys, and a trend to become underweight was observed among normal weight girls. BMI, iBMI and body fat showed good levels of tracking, with high correlations between measurements performed at 7 and 10 years of age. Furthermore, BMI and iBMI changes were correlated to body fatness changes. The present study shows the importance of carefully following children's development over time because weight disorders may appear even in previously normal weight children.

A prospective study of psychological distress and weight status in adolescents/young adults

BACKGROUND

The obesity-psychological distress relationship remains controversial.

PURPOSE

This study aims to assess whether adolescents' psychological distress was associated with body mass index (BMI) class membership determined by latent class analysis.

METHODS

Distress (anxiety, depression) and BMI were measured annually for 4 years in 1,528 adolescents. Growth mixture modeling derived latent BMI trajectory classes for models with 2-11 classes. The relationship of distress to class membership was examined in the best-fitting model using vector generalized linear regression.

RESULTS

BMI trajectories were basically flat. The five-class model [normal weight (48.8%), overweight (36.7%), obese who become overweight (3.7%), obese (9.4%), and severely obese (1.3%)] was the preferred model (Bayesian information criterion = 22789.2, df = 31; ρ = 0.84). Greater distress was associated with higher baseline BMI and, therefore, class membership.

CONCLUSIONS

Psychological distress is associated with higher BMI class during adolescence. To determine whether distress "leads" to greater weight gain may require studies of younger populations.

Adolescent summer care arrangements and risk for obesity the following school year

This longitudinal study identified common summer care arrangements for adolescents and examined whether those arrangements predicted risk for obesity (Body Mass Index (BMI) ≥ 85th percentile for age and gender) the following school year. Participants were a nationally representative sample of 1766 adolescents ages 10-18 from the Panel Study of Income Dynamics-Child Development Supplement. Results showed that, beyond measures of BMI taken before the summer and several demographic aspects known to predict obesity, youth whose summer arrangements involved regular participation in organized activities (e.g., sports) showed significantly lower risk for obesity than other youth. This was most evident during early adolescence. Youth whose regular summer arrangement was predominated by parent care without organized activity participation showed the greatest risk for obesity.

Stable genes and changing environments: body mass index across adolescence and young adulthood

The transition between adolescence and young adulthood is a developmentally sensitive time where children are at an increased risk for becoming overweight and developing obesity. Twin studies have reported that body mass index [BMI] is highly heritable, however, it remains unclear whether the genetic influences are sex-limited and whether non-additive genetic influences contribute to body mass index [BMI] during these ages. In the current report, we examined self-reported data on BMI in same [n = 2,744] and opposite-sex [n = 1,178] siblings participating in the National Longitudinal Study on Adolescent Health [Add Health]. To investigate whether the same or different genes contributed to BMI for both sexes, we fit quantitative sex-limited genetic models to three waves of data collection. At each of the three Waves of assessment, models that included additive genetic, individual-specific environment, and no sex-limited genetic influences fit the data most parsimoniously. Heritable effects on BMI at each of the three Waves were large for both sexes and ranged between .75 and .86. While genetic contributions across the ages were highly correlated, longitudinal analyses indicated that the relevant individual-specific environmental influences on BMI in adolescence and young adulthood change sizably. These results underscore the importance of understanding early genetic influences on BMI and highlight the role environmental experiences have at later ages when new genetic influences appear to make a small contribution to individual variation in BMI.

Changes and tracking of fat mass in pubertal girls

Puberty is a critical period in body composition development. The influence of puberty on the development of fat mass asks for further investigation. We investigated the development of fat mass during puberty in a longitudinal prospective study in 152 healthy nonobese white girls, initial ages between 9 to 12 years. The influence of menarcheal age and the existing of tracking of fat mass have been analyzed. In 10 years time, participants were measured on eight time points. Various anthropometric data were collected, breast development was staged according to Tanner and body composition was determined with the dual-energy X-ray absorptiometry (DXA) scan. Calculations were made with the use of a linear mixed model. Fat mass increases from 7.9 kg (23.6%) at B1 to 18.5 kg (29.3%) at B5. Fat mass is higher in girls with an early menarche than in girls with a late menarche from B2. Girls in the quartile with initially the lowest fat mass have a chance of being in the same quartile after 10 years of 77% (P < 0.001). Girls in the quartile with initially the highest fat mass, have a risk of staying in the highest quartile of 55% (P < 0.001). Menarcheal age is of great influence on the development of fat mass. Girls with an early menarche, will have a bigger fat mass, especially at the end of puberty. Tracking of fat mass exists: a high amount of fat mass in early puberty will continue to exist at young adulthood.

Patterns of change in cardiometabolic risk factors associated with the metabolic syndrome among children and adolescents: the Fels Longitudinal Study

OBJECTIVES

To examine the patterns of change in cardiometabolic risk factors associated with the metabolic syndrome in children and adolescents between the ages of 8 to 19 years.

STUDY DESIGN

Data of children and adolescents who participated in the Fels Longitudinal Study were analyzed. Body mass index, waist circumference, fasting insulin, fasting glucose, triglycerides, high-density lipoprotein cholesterol, systolic blood pressure, and diastolic blood pressure were assessed annually with a standardized protocol.

RESULTS

The proportion of participants having at least 1 change between states of high and normal risk ranged from of 11.0% for body mass index to 30.4% for triglycerides. Youth in the high-risk category at baseline had a higher proportion having changed their status for all risk factors (all P < .05) except waist circumference compared with those in the normal-risk category. There were significant time effects for all risk factors (all P < .01) except fasting glucose and triglyceride levels in metric scores, but insignificant time effects for all risk factors in Z-scores in growth curve analyses.

CONCLUSIONS

The cardiometabolic risk factors associated with the MetS were relatively stable among white children and adolescents in the normal risk category. Changes in status were common if the risk factor was elevated.