Longitudinal Examination of Hair Cortisol Concentrations and Weight Changes in Preschool-Aged Children of Latino Farmworkers

Background: Hair cortisol concentrations may serve as a measure of biologically embedded stress. While the cross-sectional association between hair cortisol and obesity in children has been examined, the data examining this relationship over time are limited. Methods: We examined hair cortisol and anthropometrics in 40 children with obesity from Latino families enrolled in a Head Start program serving farmworkers. All participants were enrolled in a clinical trial using parent mentors to encourage healthy lifestyles. We analyzed the proximal 3 cm of hair at the beginning and the end of the trial, a period of about 8 months. Linear mixed models were used to examine if changes in hair cortisol were associated with changes in adiposity. Results: Children had a median BMI percentile of 98% and parents with lower education with 25 of 40 having less than high school diploma and high food insecurity (17 of 40, 43%). Among the 40 children with valid data for both time points, the median hair cortisol concentration at baseline was 4.09 pg/mg (interquartile range [IQR] 2.65-8.68) and 6.05 pg/mg (IQR 3.95-9.33) at the end point. Increases in cortisol from baseline to follow-up had a small but significant association with decreased obesity over time. Hair cortisol did not moderate an association between food security and weight. Conclusion: In children with chronic stressors and obesity, we found that increases in cortisol over time were associated with decreases in adiposity. Further studies following hair cortisol concentrations over time are needed to understand how this biomarker relates to weight status and stressors.