Dissertation committee:
Γεώργιος Χρούσος, Ομότιμος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παναγιώτα Περβανίδου, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Χριστίνα Κανακά-Gantenbein, Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Μαρία Γιαννακούλια, Αναπληρώτρια Καθηγήτρια, Χαροκόπειο Πανεπιστήμιο
Εμμανουήλ Ζουμάκης, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Μερόπη Κοντογιάννη, Επίκουρη Καθηγήτρια, Χαροκόπειο Πανεπιστήμιο
Κωνσταντίνος Τσίγκος, Καθηγητής, Χαροκόπειο Πανεπιστήμιο
Summary:
We examined the associations between multiple indices of stress, inflammation and metabolism vs. body composition parameters in 121 (43 boys, 78 girls) children and adolescents, aged 5-15 y. Participants were divided into 2 groups: normal weight (N=40, BMI z-score = -0.1923 ± 0.6), and overweight/obese (N=81, BMI z-score= 2.1947 ± 1.4). All subjects completed the State-Trait Anxiety Inventory for Children (STAIC) and Children’s Depression Inventory (CDI), and had cortisol measured in hair, diurnal series of saliva, and morning serum. Circulating concentrations of high sensitivity C-reactive protein (hsCRP) and other inflammation biomarkers, such as ferritin, and metabolic indices, such as lipids and insulin, were also obtained. Body composition analysis was performed with a clinically validated, advanced bioimpedance apparatus (BIA), while heart rate variability (HRV) was measured as an additional stress biomarker by photoplethysmography (PPG) (eustasiometer). The overweight/obese group had a higher STAIC-state score, BMI-z score, waist-to-hip ratio, skeletal muscle mass, and total and abdominal fat mass, and a lower percent fat-free mass and bone density than the normal weight subjects. HRV did not differ between the two groups. In the entire population, percent fat mass correlated strongly with circulating hsCRP (r=0.397, p=0.001), ferritin, and other inflammatory biomarkers, as well as with indices of insulin resistance. A strong correlation between hair cortisol and serum hsCRP was also observed (r=0.777, p<0.001), suggesting presence of interrelated chronic stress and inflammation. Thus, body fat accumulation in children and adolescents was associated with an elevation in clinical and laboratory biomarkers of stress, inflammation, and insulin resistance. However, unlike adults, neither HRV, nor skeletal muscle mass were influenced negatively by adiposity. -BIA-ACC and PPG can be used as a direct screening and monitoring tool for assessing overweight- and obesity -related health risks in children and adolescents. Moreover, we examined these associations in a smaller group including only 50 girls (tanner stage 1): 25 obese girls and 25 normalweighted, age-matched girls were enrolled. In this smaller part of the study both hair cortisol concentrations and salivary cortisol AUCs were higher in the obese than the normal-weight girls (p < 0.001 and p < 0.002, respectively). A positive correlation between hair cortisol and BMI Z-score was found (rho = 0.327, p< 0.025), while hair cortisol correlated positively with salivary cortisol AUCg (rho = 0.3, p < 0.048). We conclude that obese prepubertal girls have higher hair and salivary cortisol concentrations than their age-matched lean counterparts. Hair cortisol assessment seems to be a sensitive method of evaluating systemic cortisol exposure, which is supported by our finding that hair cortisol is associated with salivary concentrations of the hormone. Cortisol is the key hormone of the stress response. Childhood obesity has been associated with cortisol production dysregulation. Our findings suggest a positive association between obesity in prepubertal girls and elevated cortisol concentrations, measured in saliva and hair. Finally, in a group of 78 girls (50 girls with obesity or overweight and 28 normal-weight girls) from our sample we examined the associations between fibroblast growth factor 21 (FGF21) and the above mentioned stress, inflammation and body composition indices. In normal-weight girls we observed a correlation between hair cortisol concentration and FGF21 levels (r=0.54, p=0.006), as well as a correlation between salivary cortisol concentration and FGF21 levels (r=0.463, p=0.020). FGF 21 possibly plays an important role in the HPA axis activation.
Keywords:
Stress, Childhood obesity, Bioelectrical Impedance, Body composition, Inflammation, Eustasiometer
