Economic disparities in parental hair cortisol are associated with externalizing behavior in children.

Socioeconomic disadvantage has been repeatedly found to increase risk for internalizing and externalizing problems in children. Socioeconomic disadvantage is theorized to exert these effects in part through its effects on parent and child stress physiology. Yet, these mechanistic pathways are not well understood. In this study, we examined the associations among socioeconomic factors, parental hair cortisol concentration (HCC) and emotional distress, and children's HCC and internalizing and externalizing symptoms. Participants were 106 typically developing 5- to 13-year-olds (57 % male; 74 % White, non-Hispanic/Latine) from a range of socioeconomic backgrounds. Hair samples 3 centimeters in length were collected from parents and children and assayed for cortisol. Parent self-reports of anxiety and depression symptoms and perceived stress were used to compute a parental emotional distress composite via factor analysis. Parents also reported on their children's internalizing and externalizing symptoms. Results indicated that lower family income-to-needs ratio was significantly associated with increased parental HCC and emotional distress. Controlling for parental emotional distress, higher parental HCC was significantly associated with greater externalizing behavior in children. Lower family income-to-needs ratio was indirectly associated with higher child HCC via higher parental HCC. These findings point to elevated parental HCC as potentially part of the mechanisms explaining socioeconomic disparities in children's mental health. Results align with calls for interventions that ensure economic resources and address caregiver well-being to support families and children.