A state-trait model of cortisol in early childhood: Contextual and parental predictors of stable and time-varying effects.

This study examined state-trait models of diurnal cortisol (morning level and diurnal slope), and whether income, cumulative risk and parenting behaviors predicted variance in trait and state levels of cortisol. The sample of 306 mothers and their preschool children included 29% families at or near poverty, 27% families below the median income, and the remaining families at middle and upper income. Diurnal cortisol, income, cumulative risk, and parenting were measured at 4 time points, once every 9months, starting when children were 36-40months. State-trait models fit the data, suggesting significant state but not trait variance in cortisol. Low income and cumulative risk were related to trait levels of diurnal cortisol with little evidence of time-varying or state effects. Stable levels of parenting predicted trait levels of diurnal cortisol and time-varying levels of parenting predicted time-varying state levels of diurnal cortisol. Findings highlight the allostatic process of adaptation to risk as well as time-specific reactivity to variability in experience.