Background: Chronic stress and increased adiposity have been associated with each other in children. Further studies are needed, however, to evaluate both the directionality of this association and the mediating metabolic mechanisms.
Objective and hypotheses: This study investigates the interrelations between BMI, body composition parameters, indices of the stress response, such as hair and salivary cortisol levels, and, metabolic mediators, such as insulin.
Method: 26 obese prepubertal girls (BMI 24.7±3.4 kg/m2) and 24 normal weight prepubertal girls (BMI 16.9±1.7 kg/m2), aged 5-10 years, were studied. Anthropometrics were obtained, conducted alongside with body composition analysis using an advanced bioimpedance apparatus (BIA-ACC, Biotekna, Venice, Italy). Scalp hair samples from the posterior vertex were collected to measure hair cortisol concentrations. Cortisol was extracted overnight in methanol, followed by solid phase extraction. Quantification of cortisol was performed using a Waters Xevo TQ-S LC-MS/MS system. Five serial saliva samples over a weekend day (0830, 1200, 1500, 1800, 2100 h) were also collected for cortisol measurements.
Results: Body fat mass as an absolute value in kg was positively associated with morning fasting insulin (P<0.01) and serial salivary cortisol excretion (computed as the area under the curve (AUC), P<0.01) while body fat mass (Kg) also correlated positively with hair cortisol (P<0.05). Skeletal muscle as a percentage (%) of total body mass was positively associated with morning fasting insulin (P<0.01) and serial salivary cortisol excretion (computed as the AUC, P<0.01) but not with hair cortisol.
Conclusion: The positive correlations between total body fat mass and hair and salivary cortisol suggest that long-term activation of the hypothalamicpituitaryadrenal axis is associated with excessive fat mass accumulation and elevated fasting insulin levels in prepubertal girls.
10 Sep 2016 - 12 Sep 2016