Does the Cortisol Awakening Response Link Childhood Adversity to Adult BMI?

Objectives: Childhood adversity is a risk factor for the development of obesity in adulthood. Dysregulated hypothalamic-pituitary-adrenal (HPA) activity, which has been associated separately with both adverse childhood experiences and obesity, has been posited as a mechanism by which stressful experiences influence body mass index (BMI); however, this mechanism has not yet been tested longitudinally. The present study uses multireporter, longitudinal data across three time points to test whether the adolescent cortisol awakening response (CAR), an index of diurnal HPA activity, mediates the association between adversity in childhood and BMI in adulthood. Method: Eighty-two youth, mothers, and fathers reported on adverse childhood experiences from middle childhood to late adolescence. During adolescence, youth provided saliva samples three times each morning across three days, which were assayed for cortisol to calculate CAR. During early adulthood, youth reported height and weight to calculate BMI. Results: Greater adversity predicted flatter CAR and higher young adult BMI. Flatter CAR partially mediated the association between childhood adversity and young adult BMI. Conclusions: Stress-related alterations to HPA activity account in part for the childhood adversity-adult obesity link. Findings are consistent with theoretical models implicating HPA alterations as linking childhood adversity to metabolic and behavioral determinants of BMI in adulthood.