Parental enforcement of bedtime during childhood modulates preference of Japanese junior high school students for eveningness chronotype.

We examined the effect of home bedtime discipline during childhood on morningness and eveningness (M-E) preference by Japanese junior high school students. M-E was assessed by the M-E Questionnaire (MEQ) of Torsvall and Akerstedt (the higher the score, the greater the preference for morningness), and parental determination of bedtime during childhood was ascertained using an original questionnaire. The average M-E score of adolescents living in urban Kochi City (mean +/- SD; 15.10 +/- 3.42) was significantly lower (P < .01) than the score of those in suburban districts (16.14 +/- 3.44). Overall, 43.1% of the junior high school students in Kochi City compared to 53.0% of the students living in suburban districts had their bedtime decided during childhood by parents (P < .01). In Kochi City, the M-E score for boys (14.62 +/- 3.51) was lower (P < .01) than girls (15.53 +/- 3.28). During childhood, parents decided the bedtime for 49% of the girls compared to 36.6% of the boys (P < .01). Boys whose bedtime was not decided by parents during childhood had a somewhat stronger preference for eveningness (14.20 +/- 3.53) (P < .05) compared to those whose bedtime was decided by parents (15.12 +/- 3.36). The results suggest bedtime discipline at home during childhood has an effect on adolescent chronotype, modulating the extent of shift to evening ness in Japanese junior high school boys in particular.     

PARENTAL ENFORCEMENT OF BEDTIME DURING CHILDHOOD MODULATES PREFERENCE OF JAPANESE JUNIOR HIGH SCHOOL STUDENTS FOR EVENINGNESS CHRONOTYPE

We examined the effect of home bedtime discipline during childhood on morningness and eveningness (M-E) preference by Japanese junior high school students. M-E was assessed by the M-E Questionnaire (MEQ) of Torsvall and Åkerstedt (the higher the score, the greater the preference for morningness), and parental determination of bedtime during childhood was ascertained using an original questionnaire. The average M-E score of adolescents living in urban Kochi City (mean ± SD; 15.10 ± 3.42) was significantly lower (P <. 01) than the score of those in suburban districts (16.14 ± 3.44). Overall, 43.1% of the junior high school students in Kochi City compared to 53.0% of the students living in suburban districts had their bedtime decided during childhood by parents (P <. 01). In Kochi City, the M-E score for boys (14.62 ± 3.51) was lower (P <. 01) than girls (15.53 ± 3.28). During childhood, parents decided the bedtime for 49% of the girls compared to 36.6% of the boys (P <. 01). Boys whose bedtime was not decided by parents during childhood had a somewhat stronger preference for eveningness (14.20 ± 3.53) (P <. 05) compared to those whose bedtime was decided by parents (15.12 ± 3.36). The results suggest bedtime discipline at home during childhood has an effect on adolescent chronotype, modulating the extent of shift to eveningness in Japanese junior high school boys in particular. (Chronobiology International, 18(5), 823–829, 2001)     

Epidemiological survey for the prevalence of overweight and abdominal obesity in Greek adolescents

This study was designed to provide estimates of overweight (OW), obesity (OB), and abdominal OB (AO) in a representative sample of adolescents throughout the whole of Greece. A total of 14,456 adolescents aged 13-19 years (6,677 boys and 7,779 girls) had direct measurements (height, weight, waist circumference (WC)) taken at school during 2003. The overall prevalence of OW including OB in the population studied was 29.4% in boys and 16.7% in girls. OB prevalence was also higher in boys than in girls (6.1% vs. 2.7%), whereas prevalence of AO was higher in girls than in boys (21.7% vs. 13.5%). Rates of OW, OB, and AO were significantly more prevalent in the Greek than in the foreign male population (immigrants). OW% in adolescent girls was independently associated with smoking and alcohol consumption. The prevalence of OW and OB in Greek adolescents is high, particularly in boys, comparable with that reported for most Mediterranean European countries. AO, mainly in adolescent girls, also appears high. Preventive and treatment strategies are urgently needed to combat this OB epidemic in Greece.     

Analysis of Age-Related Dynamics and Gender-Specific Characteristics of Spontaneous Bioelectrical Activity and Components of Auditory Evoked Potentials in Junior School Students Living in the Arctic Region of the Russian Federation

We studied neurophysiological characteristics of the age-related development in junior school students (7–8 and 10–11 years of age) living in the Arctic region of the Russian Federation. The background electroencephalograms (EEGs) were recorded during quiet wakefulness with the eyes closed and open, and event related potentials (ERP) were recorded during the passive perception of sound stimuli within the oddball paradigm in the group of children (33 subjects, 18 boys and 15 girls). A decrease of the latency period and the spatial rearrangement of mismatch negativity with an increase in the amplitude in the centrofrontal cortex have been revealed in the groups of children aged 10–11 years during the perception of a rare stimulus and a decrease of the latency period of the Р300 component in the central and parietal areas associated with the maturation of mechanisms for involuntary auditory attention. Age-specific differences in the components of auditory ERP (N1 and N2) have been shown during passive perception of rare and frequent sounds, which reflect the processes of the morphofunctional maturation of the brain cortex in healthy Arctic school students (an increase of the N1 component amplitude, a decrese of the amplitude and the latency period of the N2 component). The analysis of the background EEG characteristics has shown both the common features, such as a decrease with age of the EEG power in the Δ and θ bands in the eyes-open state, and the different direction and topographic specificities in the age-dependent reorganization of bioelectrical activity in boys and girls in the α₁ and α₂ EEG bands.     

Age-related differences in the dynamics of the skin blood flow oscillations during postocclusive reactive hyperemia

Age-related changes in peripheral microcirculation were studied using laser Doppler flowmetry in 60 apparently healthy subjects. The response of microcirculation to short-term ischemia was studied using the occlusion test. Changes in the amplitude of the peripheral blood flow oscillations were determined using time-amplitude analysis based on continuous adaptive wavelet filtration. The oscillation amplitude in the frequency range of the heart rate was found to reach the maximum with a delay after the removal of the occlusion, whereas in the range of the respiratory rhythm, no delay was observed. The hyperemic response to short-term ischemia is assumed to develop under the predominant influence of the arterial-arteriolar component, whereas the dynamics of amplitude oscillations in the range of the respiratory rhythm is a result of the devastation of the venular component after removal of occlusion. In response to short-term ischemia, the maximum oscillation amplitudes of myogenic, neurogenic, and endothelial rhythms decreased with age, which demonstrates the restriction of the regulatory control of the peripheral blood flow by the corresponding systems.     

Age- and sex-related differences in brainstem auditory evoked potentials in secondary school students living in Northern European Russia

Brainstem auditory evoked potentials (BAEPs) were studied in 46 1st- to 11th-year students (22 boys and 24 girls) of a rural secondary school in Arkhangel’sk oblast. The objective of this work was to study age- and sex-related differences in BAEP characteristics in children and adolescents, living in the North and assess the BAEP characteristics as compared to reference values. In all three age groups of students, interpeak intervals I–III, III–V, and I–V characterizing the peripheral and central conduction times were shorter in girls than in boys. Interpeak interval III–V tended to increase with age only in boys (at puberty), with a significant increase in the latencies of waves I, III, and V. The BAEP characteristics in the subjects examined included a shorter peak latency and a greater amplitude of wave I (except senior students), relatively prolonged interpeak interval I–III, and more pronounced sex-related differences in BAEPs, especially at puberty. These findings show that it is necessary to revise regional reference values for BAEPs, differentiated by sex and age, including at puberty.     

Elevated blood pressure in school children and adolescents--prevalence and associated risk factors

Elevated blood pressure (BP) in children and adolescents is determined on normative distribution of BP in healthy children. The aim of this study was to determine prevalence of high normal and elevated BP among school children and to assess associated risk factors. The study comprised 965 children (48.7% girls) in 8th grade of primary school. Data were obtained from questionnaire and anthropometric measurements. The prevalence of high normal BP was 28.5% in girls, 36.8% in boys, and elevated BP 7.9% in girls and 5.3% in boys. Overweight was present in 19.4% of girls and 9.3% boys with high normal, and 29.7% of girls and 30.8% boys with elevated BP. Hypertension in family history was the most common associated factor reported by boys and girls with high normal and elevated BP. Follow-up of children throughout school age makes possible taking of preventative measures and promotion of healthy life style.     

Age-related changes and sex differences in postural control adaptability in children during periodic floor oscillation with eyes closed

We investigated age-related changes and sex differences in adaptability of anticipatory postural control in children. Subjects comprised 449 children (4-12 years old) and 109 young adults (18-29 years old). Subjects stood with eyes closed on a force-platform fixed to a floor oscillator. We conducted five trials of 1-minute oscillation (0.5 Hz frequency, 2.5 cm amplitude) in the anteroposterior direction. Postural steadiness was quantified as the mean speed of the center of pressure in the anteroposterior direction (CoPy). In young adults, CoPy speed decreased rapidly until the third trial for both sexes. Adaptability was evaluated by changes in steadiness. The adaptability of children was categorized as "good," "moderate," and "poor," compared with a standard variation of the mean CoPy speed regression line between the first and fifth trials in young adults. Results were as follows: (1) anticipatory postural control adaptability starts to develop from age 6 in boys and 5 in girls, and greatly improves at age 7-8 in boys and 6 in girls; (2) the adaptability of children at age 11-12 (74% of boys and 63% of girls were categorized as "good") has not yet reached the same level as for young adults; (3) the adaptability at age 11-12 for girls is temporarily disturbed due to early puberty.     

Age-dependent heart rate variability in preschool children living under the conditions of the European Arctic region

The results of analysis of specific characteristics of the heart rate variability (HRV) regulation in preschool children living under the Arctic high-latitude conditions are presented. The principal ageand gender-specific differences in the HRV regulation have been inferred from the intergroup evaluations of the HRV indicators in boys and girls. A functional developmental delay has been shown in 2.5-year-old girls compared with boys of the same age group. The applied orthostatic test has shown lower reserve capacities in children of the senior group compared with the junior group. It has been shown that the mechanisms of the regulation of cardiac rhythm in girls experience higher strain during orthostasis as compared with boys. The division of children into age groups with an age difference of one year has allowed the detection of the tendency towards basically different responses to functional loads during orthostasis. The mean HRV values characteristic of four- to six-year-old children living in the Arctic are presented. It has been shown that the children living at middle latitudes have a higher adaptive potential compared with the children living in high-latitude Arctic areas.     

Longitudinal analysis of adolescent growth of ladino and Mayan school children in Guatemala: effects of environment and sex.

The rate of growth in height and the timing of adolescent growth events are analyzed for two samples of Guatemalan children. One sample includes Mayan school children, 33 boys and 12 girls between the ages of 5.00 to 17.99 years, living under poor conditions for growth and development. The second sample includes ladino children, 78 boys and 85 girls of the same age range, living under favorable conditions for growth. The Preece-Baines model I function is used to estimate mean values for rates and timing of childhood and adolescent growth events for the two groups. Significant statistical contrasts (t-tests) of these means show Mayan boys reach the age of "take-off" (TO; the onset of the adolescent growth spurt) 1.45 years later, achieve peak height velocity (PHV) 1.68 years later, and continue growing for about 2.0 years longer than do the ladino boys. Despite the Mayan boys' increased duration for growth they grow significantly more slowly than the ladinos. Mayan boys are 6.60 cm shorter than ladinos at the age of TO and are estimated to be 7.71 cm shorter than the ladinos at adulthood. Mayan girls reach the age of TO 0.93 years later than do the ladina girls, but the two groups do not differ in the age at PHV or the age at adulthood. The mean height of Mayan girls is significantly less than that of ladinas at the age of TO (6.5 cm), and this difference increases to an estimated 11.14 cm at adulthood. Possible causes of these ethnic and sex-related differences in amounts and rates of growth are discussed in relation to hypotheses about the genetic and environmental determinants of human development.     

Estimating Body Composition in Adolescent Sprint Athletes: Comparison of Different Methods in a 3 Years Longitudinal Design

A recommended field method to assess body composition in adolescent sprint athletes is currently lacking. Existing methods developed for non-athletic adolescents were not longitudinally validated and do not take maturation status into account. This longitudinal study compared two field methods, i.e., a Bio Impedance Analysis (BIA) and a skinfold based equation, with underwater densitometry to track body fat percentage relative to years from age at peak height velocity in adolescent sprint athletes. In this study, adolescent sprint athletes (34 girls, 35 boys) were measured every 6 months during 3 years (age at start = 14.8 ± 1.5yrs in girls and 14.7 ± 1.9yrs in boys). Body fat percentage was estimated in 3 different ways: 1) using BIA with the TANITA TBF 410; 2) using a skinfold based equation; 3) using underwater densitometry which was considered as the reference method. Height for age since birth was used to estimate age at peak height velocity. Cross-sectional analyses were performed using repeated measures ANOVA and Pearson correlations between measurement methods at each occasion. Data were analyzed longitudinally using a multilevel cross-classified model with the PROC Mixed procedure. In boys, compared to underwater densitometry, the skinfold based formula revealed comparable values for body fatness during the study period whereas BIA showed a different pattern leading to an overestimation of body fatness starting from 4 years after age at peak height velocity. In girls, both the skinfold based formula and BIA overestimated body fatness across the whole range of years from peak height velocity. The skinfold based method appears to give an acceptable estimation of body composition during growth as compared to underwater densitometry in male adolescent sprinters. In girls, caution is warranted when interpreting estimations of body fatness by both BIA and a skinfold based formula since both methods tend to give an overestimation.     

The estimation of microcirculation state in cerebrovascular disorders by data of laser Doppler flowmetry and hemorheological parameters

The study was aimed to evaluate microvascular blood flow and theological blood properties in healthy volunteers (n = 27) and patients with cerebral accident (n = 30). To study cutaneous blood flow we used the multifunctional laser analyzer of blood microcirculation LAKK (LAZMA, Moscow) with spectrophotometric channel and wavelet analysis of blood flow oscillations. Viscosity of the whole blood, plasma, RBC aggregability and deformability were assessed. Results: microcirculation index was by 25% (p < 0.05) lower in patients compared to the control group. Computing amplitude-frequency range of blood flow oscillations revealed notable changes in the blood flow regulation mechanisms under cerebrovascular accident: the amplitudes of all active rhythms (endothelial, neurogenic and myogenic ones) were increased. In spite of such activization of regulatory mechanisms, aimed to keep essential blood supply to tissue, index of specific oxygen consumption by tissue was decreased by 21% (p < 0.05) under cerebrovascular disorders. Blood rheological properties in patients group were impaired compared to the healthy group: blood viscosity was increased because of elevated plasma viscosity, increased RBS aggreagation and decreased erythrocyte deformability. Thus, our results demonstrated the decrease of tissue perfusion, activization of vasodilating mechanisms, impaired blood rheology and the decrease of oxygen supply to tissue in patients with cerebrovascular accident. Statistical analysis revealed a number of significant correlations between the hemorheological parameters and passive rhythms of microcirculation in norm. In patients blood viscosity correlated to the amplitude of active regulatory rhythms (endothelial, neurogenic and myogenic oscillations). Close interralations between rheological and microcirculation parameters testified the important role of hemorheological factors in maintenance of microvascular blood flow and oxygen delivery to tissue.     

Body mass index, prevalence of overweight and obesity in Lithuanian children and adolescents, 1985-2002

The study provides the body mass index (BMI), the prevalence of overweight (OW) and obesity (OB) in Lithuanian children and adolescents, 1985-2002. In the 2000-2002 more than 9000 schoolchildren of 7-18 years old were investigated in the 5 biggest towns and surrounding settlements of Lithuania. These data were compared with the 1985 data. The prevalence of OW and OB was estimated using the International Obesity Task Force (IOTF) cut-off points. The prevalence of OW in Lithuanian children and adolescents was higher among younger schoolchildren in comparison with older adolescents. OW was lower among the older girls in comparison with the older boys: 4.60%-11.50%/4.80%0-13.62% in the 7-13 years girls/boys, versus 1.50%-6.60%/3.90%-9.50% in the 14-18 years old girls/boys. The prevalence of OW among younger Lithuanian adolescents did not change significantly in the last 15 years, but it slightly decreased in older boys and demonstrably diminished in older adolescent girls. In generally, the prevalence of OW among Lithuanian adolescents is low in comparison with the prevalence of OW in children from the other countries.     

The relationship between body mass index and unhealthy weight control behaviors among adolescents: The role of family and peer social support

Adolescents classified as overweight or obese are more likely to use unhealthy weight control behaviors such as skipping meals or fasting than their healthy weight peers. Adolescents with low perceived social support may be at particular risk. Therefore, the purpose of the present study was to investigate the association between adolescent overweight and obesity, indices of perceived peer and family social support, and their interaction in the use of unhealthy weight control behaviors among adolescents. The present study used data from the 2001–2002 Health Behavior in School-Aged Children collaborative survey. Participants included 4598 adolescent girls and boys in the ninth and tenth grades. Results of binary logistic regression analyses showed that obese boys and girls were more likely to use unhealthy weight control behaviors than their healthy weight peers. Boys and girls who endorsed difficult communication with their parents, low levels of parent school support, or frequent bullying were more likely to engage in unhealthy weight control behaviors than relevant comparison groups. Among girls, poor classmate relationships were associated with increased use of unhealthy weight control behaviors whereas fewer friendships were associated with decreased use. Results suggest that adolescents are at high risk for use of unhealthy weight control behaviors and would benefit from interventions to increase knowledge and social support for achieving and maintaining a healthy weight.     

Growth and Body Mass Index of Brazilians Ages 9 Through 17 Years

Obesity during adolescence is considered a strong predictor of adult obesity, and obesity and overweight have been increasing among Brazilian adults. To gauge the relative frequency of overweight among adolescents in Brazil, we compared the distributions of body mass index (kg/m²) and stature in national population based samples of the U.S. and Brazil. U.S. adolescents were on average about 10 cm taller than Brazilians, although growth spurts occurred at the same age for both populations. Brazilian adolescents were leaner than their U.S. counterparts. This difference was reduced among girls in the postpubertal period. At age 17 years, U.S. boys were about 10 kg heavier than Brazilian boys, but the difference among girls was only 2 kg. In families above the poverty level in the more developed South region, body mass index distribution for boys was closer to that of the U.S., and older girls tended to have higher body mass index than U.S. girls. Within Brazil, body mass index varied by ethnicity with Mulattos, but not Blacks, of both sexes having lower body mass index than Whites of the same age. Urban adolescents had higher body mass index than those living in rural areas. In general, the patterns seen among Brazilian adults were found among children. Among girls, in particular, overweight has become an identifiable problem during adolescence.     

Physical activity levels of normal-weight and overweight girls and boys during primary school recess

Objective: This study aimed to compare moderate‐to‐vigorous physical activity (MVPA) and vigorous physical activity (VPA) in normal‐weight and overweight boys and girls during school recess. Research Methods and Procedures: Four hundred twenty children, age 6 to 10 years, were randomly selected from 25 schools in England. Three hundred seventy‐seven children completed the study. BMI was calculated from height and weight measurements, and heart rate reserve thresholds of 50% and 75% reflected children's engagement in MVPA and VPA, respectively. Results: There was a significant main effect for sex and a significant interaction between BMI category and sex for the percent of recess time spent in MVPA and VPA. Normal‐weight girls were the least active group, compared with overweight boys and girls who were equally active. Fifty‐one boys and 24 girls of normal weight achieved the 40% threshold; of these, 30 boys and 10 girls exceeded 50% of recess time in MVPA. Eighteen overweight boys and 22 overweight girls exceeded the 40% threshold, whereas 8 boys and 8 girls exceeded the 50% threshold. Discussion: Overweight boys were significantly less active than their normal‐weight male counterparts; this difference did not hold true for girls. Even though nearly double the number of normal‐weight children achieved the 40% of MVPA during recess compared with overweight children, physical activity promotion in school playgrounds needs to be targeted not only at overweight but at other health parameters, as 40 overweight children met the 40% MVPA target proposed for recess.     

Comparison of Attitudes and Behaviors Related to Nutrition,Body Size,Dieting, and Hunger in Russian,Black-American,and White-American Adolescents

Attitudes and behaviors related to nutrition are known to differ between white-American and black-American adolescents, however, little is known about teenagers from Russia. We hypothesized that, compared with white-American or black-American teenagers, Russian teenagers would prefer a larger body size, be less likely to diet, and be less concerned about being overweight. Self-administered questionnaires were completed by 196 students in Moscow, 326 white-American, and 239 black-American adolescents who attended school in North Carolina (mean age = 16). Ideal body mass index (BMI) was calculated from measured height and the response to the question, “What do you consider to be your ideal weight?” Mean ideal BMI was higher in black-American boys (25.1) and girls (21.4) than in white-American boys (22.1) and girls (19.2), and Russian boys (21.8) and girls (19.1). After controlling for BMI, black-American girls were less than half as likely to report dieting compared with white-American girls. There were no significant differences among white-American girls and Russian girls, and there were no ethnic differences between boys in the prevalence of dieting. White-American girls and black-American girls were much more likely to identify being overweight as an important nutritional concern than were Russian girls (odds ratios >10), and there were no ethnic differences among boys. We conclude that preferences for body size, the prevalence of dieting, and concerns about being overweight were similar in Russian and white-American teens, with the exception of Russian teenaged girls who were less likely than American girls to identify being overweight as an important concern. Overall, weight-related attitudes and behaviors in Russian teenagers were more similar to those of white-American teenagers than those of black-American teenagers.     

The case report of treatment strategy for Anorexia nervosa with psychotic elements in adolescent

Eating disorders in early childhood are the same frequency in boys and girls. During adolescence eating disorders are ten (10) times more frequent in girls than in boys. Worrying is the fact that eating disorders are the third chronic illness among adolescents after obesity and asthma. Depicting this adolescent we tried to show difficulty of treatment of this disorder, where in the beginning is important to stabilize body weight and prevent somatic damages such as: heart damage, amenorrhoea, changes in EKG (electrocardiogram) and electrolyte dysbalance that could endanger the life of patient. Simultaneously it is important to recognize and treat comorbid psychological disturbances such as in this case: depression, delusions with occasional psychotic reactions combined with unrealistic thinking about the layout of her own body. There is still no cure for the treatment of eating disorders which are in growing number of reports among male adolescents.