Blunted cortisol response to stress is associated with higher body mass index in low-income preschool-aged children

No known studies have tested the hypothesis that a blunted pattern of cortisol reactivity to stress, which is often found following exposure to chronic life stressors, is associated with a higher body mass index (BMI) in very young children. Low-income children (n = 218, mean age 56.6 (range: 38.1-78.5; SD 7.0) months, 49.1% male, 56.4% white, 16.1% black, 11.5% Hispanic/Latino) participated in a series of behavioral tasks designed to elicit stress. Cortisol was sampled in saliva 5 times during the protocol, and area under the curve (AUC), representing total cortisol output during stress elicitation, was calculated. Children were weighed and height measured and body mass index (BMI) z-score was calculated. Linear regression was used to evaluate the association between cortisol AUC and BMI z-score, controlling for child age, sex, and race/ethnicity (non-Hispanic white vs. not); primary caregiver weight status (overweight, defined as BMI >= 25 vs. not); and family income-to-needs ratio. Mean child BMI z-score was 0.88 (SD = 1.03). Mean cortisol AUC was 6.11 mu g/dUmin (SD = 10.44). In the fully adjusted model, for each 1-standard deviation unit decrease in cortisol AUC, the child's BMI z-score increased by 0.17 (SE 0.07) standard deviation units (p < 0.02). A blunted cortisol response to stress, as is often seen following chronic stress exposure, is associated with increased BMI z-score in very young children. Further work is needed to understand how associations between stress, cortisol, and elevated body mass index may develop very early in the lifespan. (C) 2013 Elsevier Ltd. All rights reserved.