Does hair cortisol really reflect perceived stress? Findings from low-income mother-preschooler dyads

Abstract

Hair cortisol concentration (HCC) has emerged as an objective biological measure of stress in humans, but findings on the relationships between perceived stress and HCC and between mothers’ HCC and children’s HCC are inconsistent. To advance the understanding of HCC and its relationship with perceived stress, this study aimed to examine the relationships among mothers’ HCC, perceived stress, distress, coping, and preschoolers’ HCC in a low-income population. A correlational study was conducted with 35 Head Start mother-preschooler dyads. Mothers’ mean HCC was 6.97 pg/mg, and preschoolers’ mean HCC was 32.02 pg/mg. The receiver operating characteristic analysis identified an optimal HCC cutoff of 4.1 pg/mg based on the 10-item Perceived Stress Scale to divide mothers into low and high HCC groups. Mothers’ perceived stress was negatively related to their HCC (ρ = −0.49, p = 0.005). While there were no statistically significant relationships between mothers' HCC and their perceived distress or coping in the low HCC group, mothers' HCC in the high HCC group was positively related to their perceived coping (ρ = 0.53, p = 0.036). Mothers’ HCC was positively correlated with preschoolers’ HCC (ρ = 0.39, p = 0.030). In the high HCC group, mothers’ perceived stress and distress had very small correlations with preschoolers’ HCC. In contrast, in the low HCC group, mothers’ perceived stress and distress had very large correlations with preschoolers’ HCC (ρ = 0.83, p < 0.001; ρ = 0.74, p = 0.001, respectively). The findings suggest mothers’ coping ability plays a significant buffering role in modifying the influence of mothers’ perceived stress on preschoolers’ stress; however, considering the limited sample size, this conclusion warrants further investigation. This study provides an important foundation for studying HCC in low-income mothers and their preschoolers.