Objective: We examined associations of different adiposity measures with cortisol responses during the Trier Social Stress Test for children (TSST-C).
Design: Descriptive study.
Setting: Holdsworth Memorial Hospital, Mysore, India.
Participants: Adolescents aged 13.5y from a birth cohort were recruited (N=269, 133 boys).
Methods: The stressor (TSST-C) was 5-minutes each of public speaking and mental arithmetic tasks in front of two unfamiliar 'judges'. Salivary cortisol concentrations were measured at baseline and at regular intervals after TSST-C. Weight, height, sub scapular and triceps skinfold thickness, and waist and hip circumference were measured, and percentage body fat was estimated (fat%; bioimpedance). Body mass index (BMI) and Waist-to-hip ratio (WHR) were calculated. All variables were converted into within-cohort SD scores before analysis. Stress-induced change in cortisol concentrations from baseline (cortisol response) was examined in relation to adiposity.
Results: Stress increased cortisol concentrations significantly from baseline (mean (SD): 5.5 (6.4) ng/mL; P<0.001). Higher WHR was associated with lower cortisol response at 20 and 30-minutes after stress (~0.13 SD decrease in cortisol response per SD higher WHR, P<0.05). Higher fat% was also associated with lower cortisol response only in girls 20-minutes post-stress (0.23 SD lower response per SD higher fat%, P=0.004). Sum of skinfold thickness and BMI were not associated with cortisol responses.
Conclusion: Abdominal adiposity is associated with reduced hypothalamic-pituitary-adrenal axis reactivity to stress in this adolescent population.