Mechanisms of stress, energy homeostasis and insulin resistance in European adolescents--the HELENA study.

ABSTRACT

BACKGROUND AND AIMS: Stress is hypothesized to facilitate the development of obesity, whose the foundations are already set during childhood and adolescence. We investigated the relationship between the stress-system, selected mechanisms of energy homeostasis and insulin resistance (IR) in a sample of European adolescents. METHODS AND RESULTS: Within HELENA-CSS, 723 adolescents (12.5-17.5 years) from 10 European cities provided all the necessary data for this study. Fasting blood samples were collected for cortisol, leptin, insulin and glucose analysis. HOMA-IR was calculated from insulin and glucose concentrations. Adolescents' body fat (BF) %, age and duration of exclusive breastfeeding were assessed. For boys and girls separately, the relationship of cortisol with leptin, insulin, glucose and HOMA-IR was examined by computing Pearson correlation coefficients and Hierarchical Linear Models (HLMs), with 'city' as cluster unit, adjusting for age, BF% and duration of exclusive breastfeeding. In boys, Pearson correlation coefficients illustrated positive correlations of cortisol with insulin (r = 0.144; p = 0.013), glucose (r = 0.315; p < 0.001) and HOMA-IR (r = 0.180; p = 0.002), whilst in girls, this positive relationship was observed for leptin (r = 0.147; p = 0.002), insulin (r = 0.095; p = 0.050) and HOMA-IR (r = 0.099; p = 0.041), but not for glucose (r = 0.054; p = 0.265). Observed associations were independent of adolescents' age, BF% and duration of exclusive breastfeeding after computing HLMs. CONCLUSION: This study suggests that the stress-system is positively related to mechanisms of energy homeostasis and IR in European adolescents, and reveals a potential small gender difference in this relationship. The hypothesis that stress might facilitate the development of obesity during adolescence is supported.