北京学龄儿童青少年体格发育指标增长速度性别差异

目的 探索学龄儿童青少年体格发育指标增长速度的性别差异,为明确中国儿童青少年的生长发育规律提供科学依据.方法 基于北京市顺义区2009-2018年6～18岁学龄儿童及青少年健康体检资料,经匹配个人信息后共纳入94 122名学生,计算年龄别身高、体重、体质量指数(BMI)增长速度,以及以身高增速高峰年龄(PHA)为基点的...     

Validity of body mass index compared with other body-composition screening indexes for the assessment of body fatness in children and adolescents

BACKGROUND: Validation studies of height- and weight-based indexes of body fatness in children and adolescents have examined only small samples of school-age children. OBJECTIVE: The objective was to validate the performance of age- and sex-specific body mass index (BMI) compared with the Rohrer index (RI) and weight-for-height in screening for both underweight and overweight in children aged 2-19 y. DESIGN: Data from the third National Health and Nutrition Examination Survey (n = 11096) and a pooled data set from 3 studies that used dual-energy X-ray absorptiometry (n = 920) were examined. The receiver operating characteristic curve was used to characterize the sensitivity and specificity of these 3 indexes in classifying both underweight and overweight. Percentage body fat and total fat mass were determined by dual-energy X-ray absorptiometry. Subcutaneous fat was assessed on the basis of the average of triceps and subscapular skinfold thicknesses. RESULTS: For children aged 2-19 y, BMI-for-age was significantly better than were weight-for-height and RI-for-age in detecting overweight when average skinfold thicknesses were used as the standard, but no differences were found in detecting underweight. When percentage body fat or total fat mass was used as the standard, BMI-for-age was significantly better than was RI-for-age in detecting overweight in children aged 3-19 y. No differences were found between BMI-for-age and weight-for-height in detecting overweight or underweight. CONCLUSION: For children and adolescents aged 2-19 y, the performance of BMI-for-age is better than that of RI-for-age in predicting underweight and overweight but is similar to that of weight-for-height.     

Body mass index and neuropsychological function in healthy children and adolescents

Elevated body mass index (BMI) is associated with adverse neurocognitive outcome in adults, including reduced neuropsychological test performance. It is unknown whether this relationship also exists in children and adolescents. A total of 478 children and adolescents (age 6-19) without significant medical or psychiatric history provided demographic information and completed a computerized cognitive test battery. Participants were categorized using clinical criteria into underweight, normal weight, at risk for overweight and overweight groups based on age and gender. Partial correlation and MANCOVA analyses adjusting for age and intellectual function found no relationship between BMI and cognitive test performance in the full sample. However, analyses performed separately by gender showed that underweight females exhibited poorer memory performance than other female BMI groups. These findings suggest that elevated BMI is not associated with cognitive function in healthy children and adolescents, though underweight might be a risk factor for reduced memory performance in females. Further work is needed to clarify the inconsistent findings between adults and minors.     

Correlates of individual differences in body-composition changes resulting from physical training in obese children

BACKGROUND: No studies have been reported in children that assess correlates of body-composition changes in response to a physical training intervention. OBJECTIVE: The hypothesis studied was that variation in diet and physical activity would explain a significant portion of the interindividual variation in the response of body composition to physical training. DESIGN: The participants were 71 obese children aged 7-11 y (22 boys, 49 girls; 31 whites, 40 blacks). Body composition was measured by dual-energy X-ray absorptiometry, physical activity by a 7-d recall interview, and diet by two, 2-d recalls. The children underwent 4 mo of physical training. RESULTS: The mean attendance was 4 d/wk, the mean (+/-SD) heart rate for the 40-min sessions was 157 +/- 7 beats/min, and the mean energy expenditure was 946 +/- 201 kJ/session. On average, the percentage body fat decreased significantly in the total group, and total mass, fat-free soft tissue, bone mineral content, and bone mineral density increased, but there was a good deal of individual variability. Multiple regression models indicated that in general, more frequent attendance, being a boy, lower energy intake, and more vigorous activity were associated with healthier body-composition changes with physical training. Ethnicity was not retained as a correlate of the change of any component of body composition. CONCLUSIONS: In obese children, age, vigorous activity, diet, and baseline percentage body fat together accounted for 25% of the variance in the change in percentage body fat with physical training.     

Normalization of energy expenditure data for differences in body mass or composition in children and adolescents

The most appropriate model for normalization of energy expenditure (EE) data for body mass or composition in growing children and adolescents has not been studied extensively. In this study, we investigated allometric modeling for the normalization of EE data for body mass or composition in a large cohort of children (n = 833), ages 5-19 y for a wide range of physical activities. Anthropometry was performed by standard techniques, and total body fat-free mass (FFM) and fat mass (FM) were determined by dual-energy X-ray absorptiometry (DXA). Weight status was defined as nonoverweight or overweight based on the 95th percentile for BMI. Total energy expenditure (TEE), basal energy expenditure (BEE), sleeping energy expenditure (SEE), and cycling EE were measured during 24-h room respiration calorimetry. Walking and maximal EE (MaxEE) were measured according to a treadmill protocol. Allometric or power function models were used to identify appropriate scaling parameters for EE. For BEE and lower levels of EE, weight scaled to 0.5. For cycling and treadmill walking/running, the weight exponent approached 0.7. Scaling EE for FFM resulted in exponents of 0.6 for lower rates of EE and 0.8-1.0 for higher rates of EE. Appropriate scaling of EE for body weight and composition of children and adolescents varied primarily as a function of the level of EE. In some instances, the exponents for scaling EE by body weight or composition were influenced by gender and weight status, but not by age.     

Calcium supplementation trials and bone mass development in children, adolescents, and young adults

The development of bone mass during childhood through young adulthood is an important determinant of bone health later in life, and calcium is the major building block. Most randomized, double-blind, placebo-controlled trials of calcium supplementation have been done in girls; however, calcium supplementation in boys has been investigated in recent studies. Positive short-term effects on bone measures during growth has been shown in boys and girls, particularly in weight-bearing appendicular bone, although the lifelong effect is not certain.     

Sex differences in the school-related achievement of diadvantaged preschool children

Numerous research studies have cited sex differences in the school-related achievement test scores of children. Replication of these findings have also been reported with disadvantaged school aged children. However few studies have investigated potential sex differences in the achievement scores of preschool aged children. This study using a variety of testing techniques, investigates the cognitive and achievement performances of disadvantaged preschool aged children. Overall, no sex differences in achievement were reported and implications of these findings for curricula developers and teachers are drawn.     

Association of lean tissue and fat mass with bone mineral content in children and adolescents.

OBJECTIVES: There has been uncertainty in the adult body composition literature about whether fat mass (FM) or fat free mass is a better predictor of bone mineral content and bone mineral density. This issue has recently also been raised in the pediatric literature. Based on suggested skeletal muscle-bone relationships, this study tested the hypothesis that in children and adolescents lean tissue mass (LTM) is a better predictor of total bone mineral content (TBMC) than is FM. RESEARCH METHODS AND PROCEDURES: Subjects were 133 Italian children and adolescents, 5 to 17 years of age, undergoing a routine medical screen. FM (kilograms), LTM (kilograms), and TBMC (kilograms) were measured by DXA. Multiple regression analyses tested the independent association of FM and LTM with bone mineral content. RESULTS: Regression analyses, adjusting for pubertal status and other covariates, showed that FM and LTM were independently associated with TBMC. These associations were similar for boys and girls. TBMC was more strongly associated with LTM than FM. DISCUSSION: These observations support the hypothesis that in children and adolescents a close association exists between LTM, a measure of skeletal muscle, and skeletal characteristics.     

Effect of weight change on bone mass in female adolescents

The purpose of this study was to examine changes in bone mineral density/bone mineral content (BMD/BMC) in obese female adolescents (Tanner stages 2 to 4) pursuing a weight reduction program. This was a prospective pilot clinical investigation involving 92 obese females screened to meet inclusion criteria and required to participate in a 6-month weight loss intervention. Baseline, 6 months, and 12 months measurements were taken for total body/lumbar spine BMD/BMC and percentage body fat. Survey instrumentation included the following: calcium food frequency/24-hour dietary recall, physical activity, and psychological assessments for anxiety/self-esteem. Changes in bone measurements were compared with changes in body weight measurements using multiple linear regression. Other potentially confounding variables analyzed included bone area, calcium intake, baseline Tanner stage, activity level, and height. Total body/lumbar spine BMD/BMC changes were found to be most significantly correlated with weight changes in the subject population. Although mean weight increased, the rate of increase per a given height velocity slowed to an appropriate height for weight ratio. Individuals who lost weight did not lose BMD/BMC; however, the rate of growth declined when compared with all study subjects whose bone growth rate was consistent with normal weight female adolescents. In this study, weight changes were strongly related to bone measurement changes in an obese adolescent female population. Dietitians counseling obese young girls are encouraged to emphasize the importance of a healthy weight loss program with optimal calcium intake and inclusive of weight-bearing exercises.     

Breakfast quality differences among children and adolescents in Croatia

The aim of this study was to establish nutrient intake from breakfast in children and adolescents in Croatia (n = 1190). A quantified FFQ method was used. The results showed that 1.7% of subjects skip breakfast. Energy intake from breakfast was 26% RDA. Adolescents obtained significantly more energy from carbohydrates and less from fat than children. Children had significantly higher cholesterol and significantly lower dietary fiber intake than adolescents. Intakes of almost all examined micronutrients differed significantly according to age. Milk and dairy products were major energy contributors in children's breakfast whereas most of the adolescents' energy came from cereal products. Breakfasts containing at least one dairy food, one cereal food and fruit/fruit juice were consumed by 13.7% and 21.9% of children and adolescents respectively. A total of 33.3% and 47.6% of subjects respectively consumed milk every day while 15.9% and 10.4% did not consume milk for breakfast at all. Subjects with BMI > 85th percentile had significantly higher energy intake while those with BMI < 25th percentile had significantly lower energy intake than those of normal weight. Education about adequate nutrition and human health and providing breakfast at schools would improve dietary habits of this population.     

Sex differences in the variables associated with objectively measured moderate-to-vigorous physical activity in preschoolers

Objective

To investigate variables associated with objectively measured moderate-to-vigorous physical activity (MVPA) in German preschool children.

Methods

Cross-sectional data was collected from 649 three to six year old children (51% boys) in 52 preschools in south Germany between autumn and spring 2008−2009. Sociodemographic, health and socio-cultural variables that could affect children's objectively measured MVPA minutes, averaged over two to four week and weekend days, were tested in bivariate and multivariate linear regression models.

Results

MVPA was significantly associated with the extrinsic variables age (−4.52 min/year of age), health status (5.62 min/category), high TV time (9.22 min/category) and high parental PA (6.59 min/category) among girls. For boys, only the intrinsic variable desire to be active (5.19 min/category) was significantly, positively associated with MVPA. The final models for girls and boys explained approximately 10% and 7% of the variance, respectively, in children's MVPA.

Conclusion

We found differences by sex in variables associated with objectively measured MVPA in preschoolers. A focus on extrinsic motivators such as parental PA for girls and intrinsic motivators for boys may be an important consideration when designing interventions and PA programs for this age group.     

Sex differences in the evaluation and diagnosis of autism spectrum disorders among children

BackgroundOne of the most consistent features of the autism spectrum disorders (ASDs) is the predominance among males, with approximately four males to every female. We sought to examine sex differences among children who met case definition for ASD in a large, population-based cohort with respect to age at first developmental evaluation, age of diagnosis, influence of cognitive impairment on these outcomes, and sex-specific behavioral characteristics.MethodsWe conducted a secondary analysis of data collected for a population-based study of the prevalence of ASD. The sample comprised 2,568 children born in 1994 who met the case definition of ASD as established by the Autism and Developmental Disabilities Monitoring (ADDM) Network for ASD surveillance. Children who had a history of developmental disability and behavioral features consistent with the DSM-IV-TR criteria for autistic disorder, Asperger's disorder, and Pervasive Developmental Disorder–Not Otherwise Specified in existing evaluation records were classified as ASD cases via two paths: streamlined and nonstreamlined. Streamlined reviews were conducted if there was an ASD diagnosis documented in the records. Data were collected in 13 sites across the United States through the ADDM Network, funded by the Centers for Disease Control and Prevention.ResultsMales constituted 81% of the sample. There were no differences by sex in average age at first evaluation or average age of diagnosis among those with an existing documented chart diagnosis of an ASD. Girls were less likely than boys to have a documented diagnosis (odds ratio [OR] = 0.76, p = .004). This analysis was adjusted for cognitive impairment status. In the logistic model, with the interaction term for sex and cognitive impairment, girls with IQ of 70 or less were less likely than boys with IQ of 70 or less to have a documented diagnosis (OR = 0.70, 95% confidence interval [CI] = 0.50-0.97, p = .035). Boys with IQ greater than 70 were less likely than boys with IQ of 70 or less to have a documented diagnosis (OR = 0.60, 95% CI = 0.49-0.74, p < .001). This finding (less likely to have a documented diagnosis) was also true for girls with IQ greater than 70 (OR = 0.45, 95% CI = 0.32-0.66, p < .001). Girls were more likely to have notations of seizure-like behavior (p < .001). Boys were more likely to have notations of hyperactivity or a short attention span and aggressive behavior (p < .01).ConclusionsGirls, especially those without cognitive impairment, may be formally identified at a later age than boys. This may delay referral for early intervention. Community education efforts should alert clinicians and parents to the potential of ASDs in boys and girls.     

Bioelectrical impedance analysis models for prediction of total body water and fat-free mass in healthy and HIV-infected children and adolescents

BACKGROUND: Bioelectrical impedance analysis (BIA) is an attractive method of measuring pediatric body composition in the field, but the applicability of existing equations to diverse populations has been questioned. OBJECTIVE: The objectives were to evaluate the performance of 13 published pediatric BIA-based predictive equations for total body water (TBW) and fat-free mass (FFM) and to refit the best-performing models. DESIGN: We used TBW by deuterium dilution, FFM by dual-energy X-ray absorptiometry, and BIA-derived variables to evaluate BIA models in a cross-sectional study of 1291 pediatric subjects aged 4-18 y, from several ethnic backgrounds, including 54 children with HIV infection and 627 females. The best-performing models were refitted according to criterion values from this population, cross-validated, and assessed for performance. Additional variables were added to improve the predictive accuracy of the equations. RESULTS: The correlation between predicted and criterion values was high for all models tested, but bias and precision improved with the refitted models. The 95% limits of agreement between predicted and criterion values were 16% and 11% for TBW and FFM, respectively. Bias was significant for some subgroups, and there was greater loss of precision in specific age groups and pubertal stages. The models with additional variables eliminated bias, but the limits of agreement and the loss of precision persisted. CONCLUSION: This study confirms that BIA prediction models may not be appropriate for individual evaluation but are suitable for population studies. Additional variables may be necessary to eliminate bias for specific subgroups.     

Excess body fat negatively affects bone mass in adolescents

ObjectiveThe aim of this study was to investigate the effects of excess body fat on bone mass in overweight, obese, and extremely obese adolescents.MethodsThis study included 377 adolescents of both sexes, ages 10 to 19 y. Weight, height, body mass index (BMI), bone age, bone mineral content (BMC), and bone mineral density (BMD) were obtained by dual-energy x-ray absorptiometry. The results were adjusted for chronological age and bone age. Comparisons according to nutritional classification were performed by analysis of variance, followed by Tukey test. Linear regression models were used to explain the variation in BMD and BMC in the L1–L4 lumbar spinal region, proximal femur, and whole body in relation to BMI, lean mass, fat mass (FM), and body fat percentage (BF%), considering P < 0.05.ResultsFor all nutritional groups, average bone age was higher than chronological age. In both sexes, weight and BMI values increased from eutrophic to extremely obese groups, except for BMD and BMC, which did not differ among male adolescents, and were smaller in extremely obese than in obese female adolescents (P < 0.01). Significant differences were observed for FM and BF% values among all nutritional groups (P < 0.01). Positive, moderate to strong correlations were detected between BMD and BMC for BMI, lean mass, and FM. A negative and moderate correlation was found between BMC and BF%, and between BMD and BF% at all bone sites analyzed in males and between BF% and spine and femur BMD, in females.ConclusionThe results reveal a negative effect of BF% on bone mass in males and indicate that the higher the BF% among overweight adolescents, the lower the BMD and BMC values.     

低浓度阿托品对儿童青少年近视防控作用研究进展

近视是发育过程中常见的屈光不正,随着儿童青少年近视的高发率和低龄化,近视已成为世界性的公共卫生问题,严重危害其身心健康。儿童青少年的近视防控工作任重而道远,低浓度阿托品作为M型胆碱受体抑制剂类药物,已被医学研究证实可以有效延缓近视的进展。本文整理回顾近年来国内外相关研究,对低浓度阿托品的最佳使用浓度、临床最佳使用方案、可能存在的潜在副作用等方面进行讨论,从学校公共卫生角度论述低浓度阿托品对于学龄期学生近视防控的意义,以期为后续的阿托品临床应用和学校学生近视防控策略提供可靠依据和新思路。     

儿童青少年饮食自我效能感及健康行为调查

目的了解贵州省儿童青少年饮食相关行为自我效能感和健康饮食行为现状,为科学开展健康教育及促进健康饮食行为提供依据。方法采用自行设计儿童青少年饮食相关行为自我效能感调查表和健康饮食行为调查表对贵州省9 所学校1 398名在校中小学生(非住校生)进行问卷调查。结果贵州省省会和县级以下地区儿童青少年饮食相关行为自我效能感得分分别为(2.08±0.72)和(2.00±0.61)分,≤12和>12 周岁年龄段儿童青少年得分分别为(2.08±0.63)和(2.01±0.69)分,差异均有统计学意义(P<0.05);省会和县级以下地区儿童青少年健康饮食行为得分分别为(2.67±0.90)和(2.05±0.92)分,男生和女生得分分别为(2.26±0.94)和(2.45±0.99)分,≤12和>12周岁年龄段儿童青少年得分分别为(2.29±0.93)和(2.52±0.87)分,小学、初中及高中生得分分别为(2.33±0.95)、(2.28±0.92)和(2.53±0.87)分,差异均有统计学意义(P<0.01或P<0.001);贵州省儿童青少年饮食相关行为自我效能感与健康饮食行为得分呈正相关关系(r=0.202,P<0.001)。结论贵州省省会和县级以下地区中小学生与饮食相关行为自我效能感和健康饮食行为存在差异,应有针对性开展教育和干预工作,促进儿童青少年形成健康饮食行为。