Children's Body composition and Stress - the ChiBS study: aims, design, methods, population and participation characteristics

Exploring the impact of lifestyle and environmental exposures on appetite hormone levels in children and adolescents: An observational study

BACKGROUND

Appetite hormones are considered a promising target in fighting obesity as impaired appetite hormone levels have already been associated with obesity. However, further insights in the drivers of appetite hormone levels are needed.

OBJECTIVES

In this study, we investigated the associations of fasting appetite hormone levels with lifestyle and environmental exposures in children and adolescents.

METHODS

A total of 534 fasting blood samples were collected from children and adolescents (4-16y,50% boys) and appetite hormone levels (glucagon-like peptide-1 (GLP-1), peptide YY (PYY), pancreatic polypeptide (PP), leptin and ghrelin) were measured. Exposures included dietary quality (fiber-rich food intake, sugar propensity, fat propensity), psychosocial stress (happiness, negative emotions, negative life events and emotional problems), sleep duration, physical activity and environmental quality (long term black carbon (BC), particulate matter <2.5 μM (PM2.5), nitrogen dioxide (NO2) exposure, and green space in a 100 m and 2000 m radius around the residence). A multi-exposure score was calculated to combine all the exposures at study in one measure. Associations of individual exposures and multi-exposure score with appetite hormone levels were evaluated using linear mixed regression models adjusting for sex, age, socioeconomic status, waist-to-height ratio and multiple testing.

RESULTS

GLP-1 was associated with air pollution exposure (NO2 β* = -0.13, BC β* = -0.15, PM2.5 β* = -0.16, all p < 0.001). Leptin was associated with green space in a 100 m radius around the residence (β* = -0.11; p = 0.002). Ghrelin was associated with negative emotions (active ghrelin β* = -0.16; p = 0.04, total ghrelin β* = -0.23; p = 0.0051) and happiness (active ghrelin β* = 0.25; p < 0.001, total ghrelin β* = 0.26; p < 0.001). Furthermore, total ghrelin levels were associated with the multi-exposure score, reflecting unhealthy exposures and lifestyle (β* = -0.22; p = 0.036).

DISCUSSION

Our findings provide new insights into the associations of exposures with appetite hormone levels, which are of high interest for preventive obesity research. Further research is crucial to reveal the underlying mechanisms of the observed associations.

A multi-exposure approach to study telomere dynamics in childhood: A role for residential green space and waist circumference

BACKGROUND

Telomeres are vulnerable to various environmental exposures and lifestyle factors, encompassed in the exposome. Recent research shows that telomere length is substantially determined early in life and that exposures in childhood may have important consequences in setting later life telomere length.

OBJECTIVES

We explore in a child population the associations of 17 exposures with telomere length and longitudinal telomere change.

METHODS

Children (2.8-10.3y at baseline, 51.3% boys) were followed-up for five to seven years. Relative telomere length was measured at baseline and follow-up using quantitative real-time PCR. Exposures and lifestyle factors included: body composition (body mass index and waist circumference), dietary habits (sugar- and fat-rich food intake, vegetables and fruit intake), psychosocial stress (events, emotions, behaviour), sleep duration, physical activity, and residential environmental quality (longterm black carbon, particulate matter exposure, and residential green space). Cross-sectional (n=182) and longitudinal (n=150) analyses were assessed using linear regression models, adjusting for age, sex, socioeconomic status and multiple testing.

RESULTS

Our longitudinal analyses showed that higher residential green space at baseline was associated with (β=0.261, p=0.002) lower telomere attrition and that children with a higher waist circumference at baseline showed a higher telomere attrition (β=-0.287, p=0.001). These two predictors were confirmed via LASSO variable selection and correction for multiple testing. In addition, children with more unhealthy exposures at baseline had a significantly higher telomere attrition over the follow-up period compared to children with more healthy exposures (β=-0.200, p=0.017).

DISCUSSION

Waist circumference and residential green space were identified as predictors associated with telomere attrition in childhood. These results further support the advantages of a healthy lifestyle from early age onwards and the importance of a green environment to promote molecular longevity from childhood onwards.

Emotion Regulation Moderates the Associations of Food Parenting and Adolescent Emotional Eating

OBJECTIVE

To explore parental feeding practices and eating behavior as predictors of the child's emotional eating (EE) and child's emotion regulation (ER) as a potential moderator.

DESIGN

Parental eating behavior (emotional, external, and restrained eating), 9 parental feeding practices (restriction, food as reward, food as ER, monitoring, healthy modeling, healthy environment, child control, and child involvement), ER, and EE were analyzed cross-sectionally and 5 parental practices longitudinally (subsample, n = 115).

SETTING

Belgium.

PARTICIPANTS

Two hundred eighteen adolescents (aged 13.7 ± 1.77 years) and parent dyads.

MAIN OUTCOME MEASURES

Child's EE.

ANALYSIS

Linear regression and moderation (cross-sectional) and linear mixed models (longitudinal). Models adjusted for multiple testing with a false discovery rate of 10% (Benjamini-Hochberg), age, sex, body mass index, socioeconomic status, and cohort.

RESULTS

Cross-sectionally but not longitudinally, there was a positive association between predictors restriction and monitoring with the outcome child's EE (β = 0.19, P = 0.006; β = 0.17, P = 0.01, respectively). Restrained eating of the parent was negatively associated with the child's EE (β = -0.22, P = 0.003). The child's maladaptive ER significantly moderated the associations of 5 feeding practices and parental EE with the child's EE.

CONCLUSIONS AND IMPLICATIONS

Parents continue to play a role in the eating behavior of their adolescent offspring, not only through their feeding practices (restrictive parenting was most detrimental) but also by displaying restrained eating (beneficial). A child's ER appears as an important moderator of the established associations; however, more research is needed to better understand these observations.

Assessment of the Feasibility of a Future Integrated Larger-Scale Epidemiological Study to Evaluate Health Risks of Air Pollution Episodes in Children

Air pollution exposure can lead to exacerbation of respiratory disorders in children. Using sensitive biomarkers helps to assess the impact of air pollution on children’s respiratory health and combining protein, genetic and epigenetic biomarkers gives insights on their interrelatedness. Most studies do not contain such an integrated approach and investigate these biomarkers individually in blood, although its collection in children is challenging. Our study aimed at assessing the feasibility of conducting future integrated larger-scale studies evaluating respiratory health risks of air pollution episodes in children, based on a qualitative analysis of the technical and logistic aspects of a small-scale field study involving 42 children. This included the preparation, collection and storage of non-invasive samples (urine, saliva), the measurement of general and respiratory health parameters and the measurement of specific biomarkers (genetic, protein, epigenetic) of respiratory health and air pollution exposure. Bottlenecks were identified and modifications were proposed to expand this integrated study to a higher number of children, time points and locations. This would allow for non-invasive assessment of the impact of air pollution exposure on the respiratory health of children in future larger-scale studies, which is critical for the development of policies or measures at the population level.

Hair Cortisol, Perceived Stress, and the Effect of Group Dynamics: A Longitudinal Study of Young Men during Compulsory Military Training in Lithuania

Previous research shows a nonlinear dependency between hair cortisol concentrations and perceived stress levels. This may be due to stress being targeted at the individual level despite it also being a social phenomenon which is often affected by group dynamics. Therefore, the objective of this study was to determine the influence of perceived stress on the hair cortisol level, considering the impact of the variables of group dynamics (interpersonal, task, and norm cohesion). Information was collected on 11 groups of, in total, 112 young men in three phases of time during their compulsory military training (covering nine months in total). The classification and regression tree (C&RT) method was used to predict hair cortisol concentrations in groups. The results show that the variability of the hair cortisol level in young men groups can be explained by perceived stress only when the groups were in formation process (47.7% normalised importance in Model 1) and when the groups were working on their final tasks (37.80% normalised importance in Model 3); meanwhile, the importance of perceived stress in explaining hair cortisol concentrations is low when the group is in a routine period of a group life-span (28.9% normalised importance in Model 2). Interpersonal cohesion (normalised importance 100% in Model 1 and 80.0% in Model 3) and task cohesion (normalised importance 78.6% in Model 2) were the most important predictors in the study area. These results point to the importance of the elements of group dynamics when it comes to explaining the nature of hair cortisol as accumulated stress biomarkers in young men.

Stress Responsiveness and Emotional Eating Depend on Youngsters' Chronic Stress Level and Overweight

The persistent coexistence of stress and paediatric obesity involves interrelated psychophysiological mechanisms, which are believed to function as a vicious circle. Here, a key mechanistic role is assumed for stress responsiveness and eating behaviour. After a stress induction by the Trier Social Stress Test in youngsters (n = 137, 50.4% boys, 6–18 years), specifically those high in chronic stress level and overweight (partial η² = 0.03–0.07) exhibited increased stress vulnerability (stronger relative salivary cortisol reactivity and weaker happiness recovery) and higher fat/sweet snack intake, compared to the normal-weight and low-stress reference group. Stress responsiveness seems to stimulate unhealthy and emotional eating, i.e., strong cortisol reactivity was linked to higher fat/sweet snack intake (β = 0.22) and weak autonomic system recovery was linked to high total and fat/sweet snack intake (β = 0.2–0.3). Additionally, stress responsiveness acted as a moderator. As a result, stress responsiveness and emotional eating might be targets to prevent stress-induced overweight.

A systematic literature review on obesity: Understanding the causes & consequences of obesity and reviewing various machine learning approaches used to predict obesity

Obesity is considered a principal public health concern and ranked as the fifth foremost reason for death globally. Overweight and obesity are one of the main lifestyle illnesses that leads to further health concerns and contributes to numerous chronic diseases, including cancers, diabetes, metabolic syndrome, and cardiovascular diseases. The World Health Organization also predicted that 30% of death in the world will be initiated with lifestyle diseases in 2030 and can be stopped through the suitable identification and addressing of associated risk factors and behavioral involvement policies. Thus, detecting and diagnosing obesity as early as possible is crucial. Therefore, the machine learning approach is a promising solution to early predictions of obesity and the risk of overweight because it can offer quick, immediate, and accurate identification of risk factors and condition likelihoods. The present study conducted a systematic literature review to examine obesity research and machine learning techniques for the prevention and treatment of obesity from 2010 to 2020. Accordingly, 93 papers are identified from the review articles as primary studies from an initial pool of over 700 papers addressing obesity. Consequently, this study initially recognized the significant potential factors that influence and cause adult obesity. Next, the main diseases and health consequences of obesity and overweight are investigated. Ultimately, this study recognized the machine learning methods that can be used for the prediction of obesity. Finally, this study seeks to support decision-makers looking to understand the impact of obesity on health in the general population and identify outcomes that can be used to guide health authorities and public health to further mitigate threats and effectively guide obese people globally.

No Differential Reward Responsivity and Drive, Punishment Sensitivity or Attention for Cues Signaling Reward or Punishment in Adolescents With Obesity

Although it has been proposed that obese and healthy weight individuals might differ in their reward and punishment sensitivity, the literature shows diverse and inconsistent findings. The current study was set out to examine the role of reward and punishment sensitivity in adolescent obesity by differentiating between reward responsivity and reward drive, and by complementing self-report measures with performance-based measures indexing attention for cues signaling reward and punishment as well as effort to approach reward and avoid punishment. Participants were adolescents aged 12-23, with obesity (n = 51, adjusted BMI [(actual BMI/Percentile 50 of BMI for age and gender) × 100) between 143 and 313%], and with a healthy weight (n = 51, adjusted BMI between 75 and 129%). Individuals with obesity did not significantly differ from adolescents with a healthy weight in reward responsivity, reward drive or attention to cues signaling reward. Further, no differences in self-reported punishment sensitivity or attention for cues signaling punishment were found between obese and healthy weight adolescents. The current study thus does not corroborate the theories that general reward and punishment sensitivity play a role in obesity.

Residential landscape as a predictor of psychosocial stress in the life course from childhood to adolescence

BACKGROUND

The effects of residential landscape, i.e., land use and traffic, on psychosocial stress in children are unknown, even though childhood stress might negatively affect normal development. In a longitudinal study, we investigate whether the residential landscape predicts childhood psychosocial stress and whether associations are independent of noise and air pollution.

METHODS

Belgian children aged 6.7-12.2 (N = 172, 50.9% boys) were followed for three years (2012-2015). Information on stress was obtained using standardized behavioral and emotional questionnaires and by a measure of hair cortisol. Residential landscape, including natural, agricultural, industrial, residential areas, and traffic, in a 100-m to 5-km radius around each child's home was characterized. Cross-sectional and longitudinal associations between psychosocial stress and the residential landscape were studied using linear regression and mixed models, while adjusting for age, sex, and parental socioeconomic status.

RESULTS

Natural landscapes were positively associated with better emotional status (increased happiness and lower sadness, anxiousness, and total negative emotions, β = 0.14-0.17, 95% CI = 0.01-0.30). Similarly, we observed an inverse association between residential and traffic density with hyperactivity problems (β = 0.13-0.18, 95% CI = 0.01-0.34). In longitudinal analyses, industrial area was a predictor of increases in negative emotions, while a natural landscape was for increases in happiness. Only the effect of natural landscape was partly explained by residential noise.

CONCLUSION

Residential greenness in proximity to a child's residence might result in a better childhood emotional status, whereas poorer emotional status and behavioral problems (hyperactivity problems) were seen with residential and industrial areas and increased traffic density in proximity to a child's home.

Psychosocial stress and inflammation driving tryptophan breakdown in children and adolescents: A cross-sectional analysis of two cohorts

BACKGROUND

Tryptophan breakdown is an important mechanism in several diseases e.g. inflammation and stress-induced inflammation have been associated with the development of depression via enhanced tryptophan breakdown. Depression is a major public health problem which commonly starts during adolescence, thus identifying underlying mechanisms during early life is crucial in prevention. The aim of this work was to verify whether independent and interacting associations of psychosocial stress and inflammation on tryptophan breakdown already exist in children and adolescents as a vulnerable age group.

METHODS

Two cross-sectional population-based samples of children/adolescents (8-18 y) were available: 315 from the European HELENA study and 164 from the Belgian ChiBS study. In fasting serum samples, tryptophan, kynurenine, kynurenic acid, C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (IFN)-ɣ, soluble vascular adhesion molecule 1 (sVCAM1) and soluble intercellular adhesion molecule 1 (sICAM1) were measured. Psychological stress was measured by stress reports (subjective) and cortisol (objective - awakening salivary cortisol or hair cortisol). Linear regressions with stress or inflammation as predictor were adjusted for age, sex, body mass index, puberty, socio-economic status and country.

RESULTS

In both cohorts, inflammation as measured by higher levels of CRP, sVCAM1 and sICAM1 was associated with kynurenine/tryptophan ratio and thus enhanced tryptophan breakdown (beta: 0.145-0.429). Psychological stress was only associated with tryptophan breakdown in the presence of higher inflammatory levels (TNF-α in both populations).

CONCLUSIONS

Inflammatory levels were replicable key in enhancing tryptophan breakdown along the kynurenine pathway, even at young age and in a non-clinical sample. The stress-inflammation interaction indicated that only the stress exposures inducing higher inflammatory levels (or in an already existing inflammatory status) were associated with more tryptophan breakdown. This data further contributes to our understanding of pathways to disease development, and may help identifying those more likely to develop stress or inflammation-related illnesses.

Longitudinal association between psychosocial stress and retinal microvasculature in children and adolescents

BACKGROUND

Retinal microvessels provides a window to assess the microcirculation of heart and brain, and might reflect cardio- or cerebrovascular disease risk. Limited information exist on the relation between psychosocial stress and the microcirculation, even though psychosocial stress might trigger vascular diseases. This study investigates whether childhood psychosocial stress is a predictor of retinal microvasculature.

METHODS

We followed-up 182 Belgian children, aged 5.7-11.3 years at baseline (53.3% boys). Information about psychosocial stress was obtained using emotional, behavioral and negative life events questionnaires and hair cortisol, an objective stress marker. Retinal photographs were used to calculate vessel diameters, bifurcation angles and optimality deviation with semiautomated software. Cross-sectional and longitudinal associations were explored using multivariable regression analysis with retinal parameters in 2015 as outcome, while adjusting for age, sex, socioeconomic status, cardiovascular parameters and lifestyle factors.

RESULTS

Feelings of happiness, sadness and negative life events were associated with retinal vascular diameter, but behavior and hair cortisol were not. High stress levels over a 4-year time period (less happy, sadder and higher total negative emotions) were associated with larger venules (β = 0.21-0.43) and children who experienced more negative life events had smaller arterioles (β = -0.15). No consistent patterns were seen with bifurcation angles and optimality deviation.

CONCLUSION

Based on the results, we conclude that high levels of childhood psychosocial stress unfavorably affect the retinal vascular diameters, potentially reflecting the microvasculature of the heart and brain. It seems this might even be independent of lifestyle and BMI, but further research on mechanisms is necessary.

Hand-to-foot bioelectrical impedance analysis to measure fat mass in healthy children: A comparison with air-displacement plethysmography

AIM

To identify children at risk of overweight, assessing children's body composition in a valid way is crucial. The present cross-sectional study examines the comparability of children's fat mass percentage obtained by hand-to-foot bioelectrical impedance analysis (BIA) versus BodPod air-displacement plethysmography as a reference method.

METHODS

The body composition of 206 Belgian children (7-13 years; 7.7% overweight) was measured with BodPod and hand-to-foot BIA (Tanita BC418 with built-in formula).

RESULTS

Overall, comparability was the highest in girls. Good ranking agreement (rho = 0.819) and interchangeability (intra-class correlation (ICC) = 0.757) were found in girls but not in boys (rho = 0.568; ICC = 0.512). Although bioelectrical impedance resulted in an overall overestimation of only 0.5 fat%, it underestimated and overestimated fat% in children with, respectively, higher and lower fat%. The 95% limits of agreement distance was around 17 fat%, and there was a significant difference from the line of identity (intercept ≠ 0; slope ≠ 1).

CONCLUSIONS

Despite good ranking agreement, the use of BIA as an alternative for the BodPod is not recommended because of over-/underestimation and wide limits of agreement. It is not possible to calculate a simple correction factor for the whole fat% range to make the two approaches interchangeable.

Chronic Psychosocial Stress and Gut Health in Children: Associations With Calprotectin and Fecal Short-Chain Fatty Acids

OBJECTIVES

The mechanisms underpinning the association between chronic stress and gut health are poorly understood. We aimed to investigate the relationship between bacterial produced short-chain fatty acids, gut barrier function, and stress measures.

METHODS

A fecal sample, hair sample, and questionnaire data were collected from 113 Belgian children (8-16 years old). Biological measures of stress included hair cortisol (most proximal 3 cm) and 5-minute heart rate variability (high frequency). Self-report measures of stress included emotional problems and negative events. Fecal calprotectin was determined as a marker of intestinal inflammation and an indirect indicator of gut barrier integrity. Fecal short-chain fatty acids (butyrate, propionate, acetate, valerate, isobutyrate, and isovalerate) were measured with gas chromatography. Linear regression analyses were adjusted for sex, age, socioeconomic status, body mass index, fiber intake, and protein intake.

RESULTS

Emotional problems were significantly associated with higher butyrate (β = 0.263), valerate (β = 0.230), isovalerate (β = 0.231), and isobutyrate (β = 0.233). Heart rate variability reflecting higher parasympathetic activity was related to lower valerate levels (β = -0.217). Hair cortisol was not associated with the short-chain fatty acids. None of the stress measures and none of the fecal short-chain fatty acids were significantly related to fecal calprotectin.

CONCLUSIONS

In healthy children, the impact of chronic stress is manifested more obviously in short-chain fatty acids than in intestinal inflammation as measured by levels of calprotectin. Despite the rather counterintuitive associations with butyrate, these results point to the need for further research on gut microbiome composition.

BIS/BAS Scale in Primary School Children: Parent-Child Agreement and Longitudinal Stability

The current study provided psychometric information on the parent and child version of the Behavioural Inhibition System (BIS)/Behavioural Approach System (BAS) scale. Parent-child agreement was evaluated (N = 217, 7.5 to 14 years, 50% boys). Moreover, absolute and rank order stability of mother-reported BIS/BAS scores over a 2-year period were assessed (N = 207, 5.5 to 11 years at baseline, 49% boys). Only full measurement invariant (sub-)scales were considered in the parent-child agreement and longitudinal stability assessment. Parent and child ratings were found to be measurement invariant but discrepant on BAS Drive and BAS Reward Responsiveness. In younger children, child ratings on BAS Drive tended to be higher than parent ratings, whereas in older children, child ratings tended to be lower than parent ratings. Further, the discrepancy between the BAS Drive ratings of fathers and children was higher than the discrepancy between the BAS Drive ratings of mothers and children. Finally, the study results suggested 2-year absolute and rank order stability of the measurement-invariant, mother-reported BIS and BAS Drive scores in children aged 5.5 to 11 years at baseline.

Longitudinal Associations of Leptin and Adiponectin with Heart Rate Variability in Children

For early prevention of cardiovascular disease, early detection and risk factor insights are necessary. The autonomic balance reflects cardiovascular risk and can be measured by heart rate variability (HRV). Therefore, our purpose is to examine associations between HRV and the energy-related biomarkers leptin and adiponectin in children. Participants of this study were Belgian children recruited for the longitudinal ChiBS study (year 2010-2012). HRV was measured and fasting blood samples were taken in 249 children at baseline (4.4-11.0 y) and 223 children at follow-up (6.7-12.2 y). Cross-sectional and longitudinal linear regression analyses were separated by sex and adjusted for age, socio-economic status, body fat%, negative emotions, puberty, and mean heart rate. Leptin was a negative cross-sectional and longitudinal predictor of parasympathetic activity in boys; while leptin in girls was cross-sectionally associated with higher LF and LF/HF suggesting sympathetic predominance. Adiponectin was a negative cross-sectional and longitudinal predictor of parasympathetic activity in boys; but when adjusting for mean heart rate, this effect disappeared and adiponectin was a positive cross-sectional and longitudinal predictor of parasympathetic activity in girls. These results stress the importance of considering sex differences and adjustment for heart rate in testing HRV predictors. Leptin seemed disadvantageous for the autonomic balance, while adiponectin seemed advantageous for the autonomic balance in girls only. More research is needed to see whether leptin and adiponectin are interesting in cardiovascular screening/prevention or in determining the cardiovascular gain during weight loss follow-up.

Children's psychosocial stress and emotional eating: A role for leptin?

OBJECTIVE

Psychosocial stress can be a health threat by stimulating unhealthier eating behaviors. We aim to test the role of the hormone leptin in the association between stress and diet/emotional eating as detected in primary school children.

METHOD

In a two-wave longitudinal study with 308 Belgian children (5-12y) in 2010-2012, the association of fasting serum leptin with reported stress (negative events and emotional problems), measured stress by salivary cortisol (overall cortisol output and awakening response), emotional eating and food consumption frequency was examined. Analyses were split by sex. Mediation and moderation by leptin change were tested.

RESULTS

One stress marker (overall cortisol output) was significantly correlated with high leptin levels, but only in girls and cross-sectionally. Only in boys, leptin was associated with low emotional eating. Leptin was not a significant predictor of unhealthy food consumption. Leptin change was not a mediator but an enhancing moderator in the link between stress (high cortisol output and emotional problems) and emotional eating in girls: high reports of emotional eating in 2012 were present in the case of combined high 2-year leptin increase and high stress at baseline.

DISCUSSION

Stress (represented by emotional problems and high daily cortisol) seems to lead to hyperleptinemia in girls; and the combination of high stress and hyperleptinemia might make girls more vulnerable to stress-induced eating. No functional data on leptin sensitivity were present, but results might suggest that stress induces lower sensitivity to the anorexigenic leptin activity. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2017; 50:471-480).

Body fat evolution as predictor of retinal microvasculature in children

OBJECTIVES

Microvascular changes may represent an underlying mechanism through which overweight contributes to cardiovascular disease development. Therefore, the aim of this study was to investigate whether changes in children's body fat over time are associated with the retinal microvasculature, a marker of cardiovascular aging.

METHODS

In a longitudinal design, 171 healthy Flemish children (53.8% boys) were followed-up for 7 years (2008-2015), aged 2.7-8.1 years at baseline.Z-scores of body mass index (zBMI; 4.1% overweight), waist circumference (zWC) and fat mass index (zFMI by BODPOD) were obtained using standardized protocols during each visit. Retinal arteriolar (central retinal arteriolar equivalent (CRAE)) and venular equivalents (central retinal venular equivalent (CRVE)) were measured from digital retinal photographs (2015) using IVAN software. Cross-sectional and longitudinal associations between changes in body fat and retinal microvasculature were explored using multivariable regression analysis, while controlling for age, sex, mean arterial pressure, alternate retinal caliber, physical activity, diet and birth weight.

RESULTS

In cross-sectional analysis, children with high zFMI had a higher CRVE, but only in boys (β=0.25, P=0.02). In addition, boys with high zFMI had also a lower CRAE to CRVE ratio (β=-0.26, P=0.03). No associations were seen with the CRAE, or between zBMI or zWC and the retinal microvasculature. Only changes in zFMI over time were found to be positively associated with the CRVE in boys (β=0.38, P=0.01).

CONCLUSIONS

Our analysis over a 7-year period shows that changes in body fat during childhood are already associated with the CRVE (especially in boys).

Fat and lean tissue accretion in relation to reward motivation in children

'Reward sensitivity' explains inter-individual differences in the motivation to obtain rewards when reward cues are perceived. This psychobiological trait has been linked to higher consumption of palatable food when exposed to palatable food cues. The current study aims to examine if reward sensitivity explains differences in patterns of fat and lean tissue accretion over time in children. A longitudinal observational study with measurement waves in 2011 (baseline), 2012, 2013, and 2015 was conducted. The sample was a population-based Flemish cohort of children (n = 446, 50% boys and 5.5-12 years at baseline; 38.8% of the baseline sample also participated in 2015). Baseline reward sensitivity of the children was assessed by parent ratings on the Drive subscale of the Behavioral Inhibition System/Behavioral Approach System scales. Age- and sex-independent Fat and Lean Mass Index z-scores (zFMI and zLMI respectively) were computed for each study wave based on air-displacement plethysmography. In girls, but not boys, reward sensitivity was positively associated with the baseline zFMI and zLMI (95% confidence intervals of unstandardized estimates: 0.01 to 0.11 and 0.01 to 0.10 respectively, P values 0.01 and 0.02 respectively). Further, reward sensitivity explained 14.8% and 11.6% of the change in girls' zFMI and zLMI respectively over four years: the zFMI and zLMI increased and decreased respectively in high reward sensitive girls (95% confidence intervals of unstandardized estimates: 0.01 to 0.11 and -0.12 to -0.01 respectively, P values 0.01 and 0.02 respectively). Hence, girls high in reward sensitivity had significantly higher adiposity gain over four years parallel with lower increase in lean mass than was expected on the basis of their age and height. These results may help to identify appropriate targets for interventions for obesity prevention.

Stress exposure and psychological stress responses are related to glucose concentrations during pregnancy

OBJECTIVES

The role of stress in the development of gestational diabetes mellitus (GDM) has so far been neglected. We investigated the impact of stress exposure (pregnancy-related and pregnancy-unrelated major life events), psychological stress responses (perceived stress, subjective experience of stress, anxiety, depression, sleep), and physiological stress responses (salivary cortisol, plasma copeptin levels) on glucose concentrations during pregnancy.

DESIGN

Cross-sectional study, including 203 pregnant women at the maternity department of a Swiss university hospital.

METHODS

All women underwent routine screening for GDM with a 75-g oral glucose-tolerance test at 24-30 weeks of gestation. Pregnancy-related and pregnancy-unrelated major life events, perceived stress, general psychological distress, anxiety, depression, and amount of sleep were assessed by validated self-report questionnaires. Cortisol was measured using fasting and bedtime saliva samples, and copeptin using fasting plasma. All data were collected before communication of the screening test results.

RESULTS

Significant positive associations were found between the number of pregnancy-related major life events and fasting glucose, while there was no association with pregnancy-unrelated major life events. More anxiety and depressive symptoms, a higher general level of distress, and a shorter duration of sleep were related to fasting glucose, although the latter two were no longer significant when age and BMI were controlled for. However, physiological stress responses were not associated with glucose concentrations. When testing for unique associations with fasting glucose, more general distress and shorter duration of sleep independently accounted for higher fasting glucose levels. Finally, when comparing women with and without GDM, we found that women who subsequently received the diagnosis of GDM reported more pregnancy-related life events.

CONCLUSIONS

Some indicators of stress exposure and psychological stress responses were associated with fasting glucose concentrations in pregnant women, thus representing important risk factors for GDM development. Statement of contribution What is already known on this subject? Only approximately half of women with gestational diabetes mellitus (GDM) report any known risk factors. Women after GDM diagnosis reported more major life events compared to healthy pregnant controls. What does this study add? Stress exposure and psychological stress responses were associated with fasting glucose concentrations in pregnant before women were aware of their GDM diagnosis. These represent important risk factors for GDM development and potential targets for intervention.

The influence of dairy consumption, sedentary behaviour and physical activity on bone mass in Flemish children: a cross-sectional study

Background

This cross-sectional study aimed to look for an association in young children between whole body bone mineral content (BMC) and areal bone mineral density (aBMD) and dairy consumption as well as sedentary behaviour (SB) and physical activity (PA). Moreover, we investigated whether there was an interaction effect between dairy consumption and SB or PA on BMC and aBMD.

Methods

Healthy children (6-12 years) were recruited from primary schools. Body composition and whole body bone mass were measured with dual-energy X-ray absorptiometry (DXA), dairy consumption was assessed with a food frequency questionnaire (FFQ) and PA and SB with an accelerometer. In total, 272 children underwent a DXA scan. Complete FFQ data were available for 264 children and 210 children had matching data from accelerometry recordings. Regression analyses were used to study the associations between (1) BMC and aBMD and (2) dairy consumption, SB and PA, adjusting for age, gender, pubertal stage, height and body composition.

Results

Dairy consumption was positively associated with whole body BMC and aBMD (absolute value as well as z-score), after correction for relevant confounders. SB was negatively associated with aBMD z-score and light PA was positively associated with both BMC and aBMD z-score. No gender differences were found. Moreover, an interaction effect between vigorous PA (VPA) and dairy consumption on aBMD (z-score) and BMC z-score was found, indicating that children with both high VPA and high dairy consumption had higher values for BMC and aBMD of the whole body minus the head.

Conclusion

Already at young age, PA and dairy consumption positively influence whole body bone mass assessed by DXA. Moreover, this study indicates clearly that SB is negatively associated with whole body bone density. Promoting regular PA and sufficient dairy consumption in young children and limiting SB can be expected to positively influence their bone mass accumulation, which can help in the prevention of osteoporosis later in life.

Pediatric reference values for tibial trabecular bone mineral density and bone geometry parameters using peripheral quantitative computed tomography

The purpose of this study was to establish reference data, in relation to age and body height, for tibial trabecular and cortical volumetric bone mineral density, bone mineral content, and cross-sectional bone geometry in healthy children and adolescents using peripheral quantitative computed tomography (pQCT). Over a 2-year period, 432 (207 male and 225 female) healthy children, with an age range of 5 to 19 years, from 6 different geographic areas in Belgium were recruited. Multislice pQCT scanning (XCT2000(®), Stratec Medizintechnik, Pforzheim, Germany) was performed at the distal metaphysis (at the 4% site) and the distal diaphysis (14 and 38% sites) of the tibia of the dominant leg. Gender-specific centile curves in relation to age and body height were generated with the LMS method for total and trabecular volumetric bone mineral density (at 4% site), bone mineral content, total bone cross-sectional area, periosteal circumference (all at 4, 14, and 38% site), cortical volumetric bone mineral density, endosteal circumference, and cortical thickness (at the 14 and the 38% site). These centile curves can be used for the interpretation of pQCT results at the 4, 14, and 38% site of the tibia in European children and adolescents, at least when a similar methodology is used.

The influence of dairy consumption and physical activity on ultrasound bone measurements in Flemish children

The study's aim was to analyse whether children's bone status, assessed by calcaneal ultrasound measurements, is influenced by dairy consumption and objectively measured physical activity (PA). Moreover, the interaction between dairy consumption and PA on bone mass was studied. Participants of this cross-sectional study were 306 Flemish children (6-12 years). Body composition was measured with air displacement plethysmography (BodPod), dairy consumption with a Food Frequency Questionnaire, PA with an accelerometer (only in 234 of the 306 children) and bone mass with quantitative ultrasound, quantifying speed of sound (SOS), broadband ultrasound attenuation (BUA) and Stiffness Index (SI). Regression analyses were used to study the associations between dairy consumption, PA, SOS, BUA and SI. Total dairy consumption and non-cheese dairy consumption were positively associated with SOS and SI, but no significant association could be demonstrated with BUA. In contrast, milk consumption, disregarding other dairy products, had no significant effect on calcaneal bone measurements. PA [vigorous PA, moderate to vigorous physical activity (MVPA) and counts per minute] was positively associated and sedentary time was negatively associated with BUA and SI, but no significant influence on SOS could be detected. Dairy consumption and PA (sedentary time and MVPA) did not show any interaction influencing bone measurements. In conclusion, even at young age, PA and dairy consumption positively influence bone mass. Promoting PA and dairy consumption in young children may, therefore, maximize peak bone mass, an important protective factor against osteoporosis later in life.

Caregivers' hair cortisol: a possible biomarker of chronic stress is associated with obesity measures among children with disabilities

BACKGROUND

The stress of caring for a loved one with chronic illness has been associated with childhood obesity. Hair cortisol has been proposed as a novel biomarker of chronic psychological stress. This study aimed to evaluate the associations between caregivers' chronic stress evaluated by hair cortisol concentrations (HCC) and obesity measures among children with disabilities such as autism.

METHODS

Eighty-five dyads of children with disabilities and their primary caregivers participated in the study between April and July 2013 in the Patagonia Region, Chile. Trained research staff conducted anthropometric measurements of children and caregivers. Cortisol concentrations, extracted from hair samples with methanol, were quantified using liquid chromatography tandem mass spectrometry. Pearson's correlation coefficients and linear regression models were used to examine the associations between caregiver HCC (log-transformed) and child obesity measures with adjustment for covariates.

RESULTS

Caregiver HCC were positively and significantly correlated with child weight (child age- and sex-adjusted r =0.23, P = 0.036), body mass index (BMI) (r = 0.23, P = 0.035), circumferences of neck (r = 0.30, P = 0.006), waist (r = 0.27, P = 0.014), and hip (r = 0.22, P = 0.044). After adjustment for children's age and sex, caregiver HCC were significantly related to child weight (kg) (beta = 4.47, standard error (SE) = 2.09), BMI (kg/m(2)) (beta = 1.52, SE = 0.71), neck circumference (cm) (beta = 1.20, SE = 0.43), waist circumference (cm) (beta = 3.75, SE = 1.50), and hip circumference (cm) (beta = 3.02, SE = 1.48). Caregiver HCC were also positively but not statistically significantly associated with child waist-to-hip ratio (beta = 0.01, SE = 0.01; P = 0.191) or body fat percentage (%) (beta = 2.11, SE = 1.28; P = 0.104). Further adjustment for other covariates including child disability diagnosis and caregiver age, sex, education, current smoking, perceived stress, and caregiver BMI did not change the results substantially.

CONCLUSIONS

Chronic stress of caregivers, evaluated by increased cortisol concentrations in hair, was positively associated with obesity measures among children with disabilities.

Cross-lagged associations between children's stress and adiposity: the Children's Body Composition and Stress study

OBJECTIVE

The public health threats stress and adiposity have previously been associated with each other. Longitudinal studies are needed to reveal whether this association is bidirectional and the moderating factors.

METHODS

In the longitudinal Children's Body Composition and Stress study, 316 children (aged 5-12 years) had measures of stress (questionnaires concerning negative life events, problem behavior, and emotions) and adiposity (body mass index, waist-to-height ratio, and fat percentage) in three waves at 1-year intervals. The bidirectionality of the association between stress and adiposity was examined using cross-lagged analyses. We tested moderation by cortisol and life-style (physical activity, screen time, food consumption, eating behavior and sleep duration).

RESULTS

Adiposity (body mass index: β = 0.48 and fat percentage: β = 0.18; p < .001) were associated with subsequent increased stress levels, but stress was not directly related to subsequent increases in adiposity indices. Cortisol and life-style factors displayed a moderating effect on the association between stress and adiposity. Stress was positively associated with adiposity in children with high cortisol awakening patterns (β = 0.204; p = .020) and high sweet food consumption (β = 0.190; p = .031), whereas stress was associated with lower adiposity in the most active children (β = -0.163; p = .022).

CONCLUSIONS

Stress is associated with the development of children's adiposity, but the effects depend on cortisol levels and life-style factors. This creates new perspectives for multifactorial obesity prevention programs. Our results also highlight the adverse effect of an unhealthy body composition on children's psychological well-being.

The influence of parenting style on health related behavior of children: findings from the ChiBS study

OBJECTIVE

Exploring associations between parenting behavior and children's health related behavior including physical activity, sedentary behavior, diet and sleep.

METHODS

We recruited 288 parents and their children (6-12y old). Children's weight and height were measured. Fat percentage was determined by air displacement plethysmography. Parents reported socio-demographic data, sleep information, physical activity and sedentary behavior of their child and completed the Comprehensive General Parenting Questionnaire (CGPQ) and a Food Frequency Questionnaire. Children completed the Dutch Eating Behavior Questionnaire. Associations between parenting behavior (CGPQ) and children's health related behavior were assessed with univariate and multiple regression analyses.

RESULTS

A small positive correlation was found between sweet food consumption frequency and "coercive control" (r = 0.139) and a small negative correlation between fruit and vegetables consumption frequency and "overprotection" (r = -0.151). Children consumed more frequently soft drinks when their parents scored lower on "structure" (r = -0.124) and higher on "overprotection" (r = 0.123); for the light soft drinks separately, a small positive correlation with "behavioral control" was found (r = 0.172). A small negative correlation was found between "emotional eating" and "structure" (r = -0.172) as well as "behavioral control" (r = -0.166). "Coercive control" was negatively correlated with the child's sleep duration (r = -0.171). After correction for confounding factors, the following significant associations were found: (1) a small negative association between "structure" and soft drinks consumption (β = -0.17 for all soft drinks and -0.22 for light soft drinks), (2) a small positive association between "behavioral control" and light soft drinks (β = 0.34), (3) a small positive association of "nurturance" and "coercive control" with sedentary behavior (β = 0.16 for both parent constructs) and (4) a small negative association between the parenting construct "coercive control" and sleep duration (β = -0.23).

CONCLUSION

The significant but small associations between parenting constructs and the investigated variables suggest that different aspects of parenting style play an important role in the genesis of the health related behavior of children. Overall, our findings suggest that health professionals should encourage parents to apply the more positive parenting constructs i.e., more "structure" and "behavioral control", and less "coercive control". They could, for instance, supervise and manage their child's activities and help their child to achieve certain goals.

Children's sleep and autonomic function: low sleep quality has an impact on heart rate variability

OBJECTIVES

Short sleep duration and poor sleep quality in children have been associated with concentration, problem behavior, and emotional instability, but recently also with disrupted autonomic nervous function, which predicts cardiovascular health. Heart rate variability (HRV) was used as noninvasive indicator of autonomic function to examine the influence of sleep.

DESIGN

Cross-sectional and longitudinal observational study on the effect of sleep on HRV.

PARTICIPANTS

Belgian children (5-11 years) of the ChiBS study in 2010 (N = 334) and 2011 (N = 293).

INTERVENTIONS

N/A.

METHODS

Sleep duration was reported and in a subgroup sleep quality (efficiency, latency, awakenings) was measured with accelerometry. High-frequency (HF) power and autonomic balance (LF/HF) were calculated on supine 5-minute HRV measurements. Stress was measured by emotion and problem behavior questionnaires. Sleep duration and quality were used as HRV predictors in corrected cross-sectional and longitudinal regressions. Stress was tested as mediator (intermediate pathway) or moderator (interaction) in sleep-HRV associations.

RESULTS

In both cross-sectional and longitudinal analyses, long sleep latency could predict lower HF (parasympathetic activity), while nocturnal awakenings, sleep latency, low sleep efficiency, and low corrected sleep duration were related to higher LF/HF (sympathetic/parasympathetic balance). Parental reported sleep duration was not associated with HRV. The significances remained after correction for stress. Stress was not a mediator, but a moderator (enhancer) in the relationship between sleep quality and HRV.

CONCLUSIONS

Low sleep quality but not parent-reported low sleep duration leads to an unhealthier heart rate variability pattern (sympathetic over parasympathetic dominance). This stresses the importance of good sleep quality for cardiovascular health in children.

Relation between salivary cortisol as stress biomarker and dietary pattern in children

PURPOSE

Psychological stress has been suggested to result in hormonal effects (e.g. changes in cortisol pattern) that may change food selection in unhealthy ways. This study examines whether children's dietary pattern is indeed related to salivary cortisol levels.

METHODS

In 323 children (5-10 years old) participating in the Belgian ChiBS study, salivary cortisol samples, a biomarker for stress, was sampled when waking up, 30 and 60 min after wake up and in the evening on two consecutive weekdays. Data on the children's dietary pattern (frequency of sweet foods, fatty foods, snacks, fruit and vegetables) was collected with a food frequency questionnaire. Multilevel time modelling was used with adjustments for sex, age, body mass index, parental education and wake up time.

RESULTS

Higher overall cortisol levels and a large cortisol awakening response (CAR) were associated with more frequent consumption of sweet foods. A steeper diurnal cortisol decline was associated with a higher sweet, fatty and snack food consumption frequency. No associations with fruit and vegetables consumption were found.

CONCLUSIONS

High cortisol levels were linked to an unhealthier dietary pattern (more fatty food, snacks and especially sweet food). This supports the theory of cortisol-induced comfort food preference and strengthens the stress-diet relation.

Cross-sectional relationship between chronic stress and mineral concentrations in hair of elementary school girls

Chronic stress exposure is associated with diverse negative health outcomes. It has been hypothesised that stress may also negatively affect the body's mineral status. This study investigates the association between chronic stress and long-term mineral concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), phosphorus (P) and zinc (Zn) in scalp hair among elementary school girls. Complete information on child-reported stress estimates (Coddington Life Events Scale (CLES)), hair cortisone and hair mineral concentrations, and predefined confounders in the stress-mineral relationship (i.e. age, body mass index, physical activity, diet, hair colour and parental education) was provided cross-sectionally for 140 girls (5-10 years old). The relationship between childhood stress measures (predictor) and hair minerals (outcome) was studied using linear regression analysis, adjusted for the abovementioned confounders. Hair cortisone concentrations were inversely associated with hair mineral concentrations of Ca, Mg, Zn and the Ca/P ratio. Children at risk by life events (CLES) presented an elevated Ca/Mg ratio. These findings were persistent after adjustment for confounders. This study demonstrated an independent association between chronic stress measures and hair mineral levels in young girls, indicating the importance of physiological stress-mineral pathways independently from individual or behavioural factors. Findings need to be confirmed in a more heterogeneous population and on longitudinal basis. The precise mechanisms by which stress alters hair mineral levels should be further elucidated.

Cortisone in hair of elementary school girls and its relationship with childhood stress

Children may be exposed to stressful situations with adverse effects on their physiological and psychological health. As cortisone may be a useful additional biomarker for stress research and as it has been shown to be detectable in human hair, this study measured physiological concentrations of hair cortisone in 223 elementary school girls and explored its relationship with child-reported estimates of stress, more specifically questionnaires on major life events (i.e., Coddington Life Events Scale for Children), emotions (i.e., anger, anxiety, sadness, and happiness), and coping strategies (i.e., emotion- versus problem-focused coping). Cortisone concentrations were positively correlated with the overall life event score for the past 6 months (rho = 0.223, p = 0.004), as well as with the negative event score for this period (rho = 0.227, p = 0.003; N = 165). Cortisone did not correlate with emotions or coping styles reported by the children.

CONCLUSION

Despite its exploratory nature, this study may suggest elevated hair cortisone concentrations under psychosocial stress in young children. Although the observed findings should be interpreted with prudence, this study may encourage further research elucidating the potential importance and relevance of hair cortisone analysis as an additional or substituting stress biomarker for hair cortisol.

Hair minerals and metabolic health in Belgian elementary school girls

Literature has repeatedly shown a relationship between hair minerals and metabolic health, although studies in children are currently lacking. This study aims to investigate hair levels of calcium (Ca), copper (Cu), magnesium (Mg), iron (Fe), phosphorus (P), and zinc (Zn) and their association with (1) overweight/obesity and (2) metabolic health in Flemish elementary school girls between 5 and 10 years old. Two hundred eighteen girls participated in this study as part of the baseline ChiBS project. Children were subjected to physical examinations, blood and hair sampling. Hair minerals were quantitatively determined via inductively coupled plasma-mass spectrometry after microwave-assisted acid digestion. Body mass index (BMI) and body fat percentage (BF%) were studied as anthropometric parameters, and a metabolic score (including systolic and diastolic blood pressure, insulin resistance and non-high-density lipoprotein (non-HDL) cholesterol as parameters) was calculated, with higher scores indicating a more unhealthy metabolic profile. Hair Ca, Ca/Mg, and Ca/P positively correlated with the anthropometric parameters. An inverse correlation was observed between Ca, Mg, and Ca/P in hair and the metabolic score. Inverse correlations were also observed for individual metabolic parameters (i.e., diastolic blood pressure, homeostasis model assessment for insulin resistance, non-HDL cholesterol). In particular, girls with a total number of three or more metabolic parameters above the age-specific 75th percentile showed significantly reduced hair Ca, Mg, and Ca/P concentrations. This study showed reduced hair mineral concentrations in young girls with a more unhealthy metabolic profile. Positive associations were observed between some minerals and BMI and BF%.

Mineral concentrations in hair of Belgian elementary school girls: reference values and relationship with food consumption frequencies

Although evidence suggests that hair elements may reflect dietary habits and/or mineral intake, this topic remains controversial. This study therefore presents age-specific reference values for hair concentrations of Ca, Cu, Fe, Na, Mg, P and Zn using the LMS method of Cole, and investigates the relationship between dietary habits (i.e. food consumption frequencies) and hair mineral concentrations in 218 Belgian elementary school girls by reduced rank regression (RRR). Hair minerals were quantitatively determined via inductively coupled plasma-mass spectrometry after microwave-assisted acid digestion of 6-cm long vertex posterior hair samples. The Children's Eating Habits Questionnaire-Food Frequency Questionnaire was used to obtain information on food consumption frequency of 43 food items in the month preceding hair collection. The established reference ranges were in line with data for other childhood or adolescent populations. The retained RRR factors explained 40, 50, 45, 46, 44 and 48 % of the variation of Ca, Cu, Fe, Mg, P and Zn concentrations in hair, respectively. Although this study demonstrated that a large proportion of hair mineral variation may be influenced by food consumption frequencies in elementary school girls, a number of food groups known to be rich sources of minerals did not show a relation with certain hair minerals. Future research should focus on mechanisms and processes involved in mineral incorporation and accumulation in scalp hair, in order to fully understand the importance and influence of diet on hair minerals.