In a predominantly low-income population-based longitudinal sample of 1,292 children followed from birth, higher level of salivary cortisol assessed at ages 7, 15, and 24 months was uniquely associated with lower executive function ability and to a lesser extent IQ at age 3 years. Measures of positive and negative aspects of parenting and household risk were also uniquely related to both executive functions and IQ. The effect of positive parenting on executive functions was partially mediated through cortisol. Typical or resting level of cortisol was increased in African American relative to White participants. In combination with positive and negative parenting and household risk, cortisol mediated effects of income-to-need, maternal education, and African American ethnicity on child cognitive ability.

Parents' physiological regulation may support infants' regulation. Mothers (N= 152) and 6-month-old male and female infants were observed in normal and disrupted social interaction. Affect was coded at 1-s intervals and vagal tone measured as respiratory sinus arrhythmia (RSA). Maternal sensitivity was assessed in free play. Mothers and infants showed opposite patterns of RSA change. During disrupted interaction, mothers' RSA increased and infants' decreased, suggesting self-regulation of distress. During reunion, although the typical pattern was for infants to return to baseline levels, infants of sensitive mothers and sensitive mothers both showed a significant decrease in RSA from baseline. Mothers' and infants' physiological responses may be a function of mutual responsiveness.

This paper examined the relation of early environmental adversity associated with poverty to child resting or basal level of cortisol in a prospective longitudinal sample of 1,135 children seen at 7, 15, 24, 35, and 48 months of age. We found main effects for length of time in poverty, poor housing quality, African American ethnicity, and low positive caregiving behavior in which each was uniquely associated with an overall higher level of cortisol from age 7 months to 48 months. We also found that two aspects of the early environment in the context of poverty, adult exits from the home and perceived economic insufficiency, were related to salivary cortisol in a time dependent manner. The effect for the first of these, exits from the home, was consistent with the principle of allostatic load in which the effects of adversity on stress physiology accumulate over time. The effect for perceived economic insufficiency was one in which insufficiency was associated with higher levels of cortisol in infancy but with a typical but steeper decline in cortisol with age at subsequent time points.

The authors examined the associations between socioeconomic status (SES), race, maternal sensitivity, and maternal negative-intrusive behaviors and language development in a sample selected to reduce the typical confound between race and SES (n = 146). Mother-child interactions were observed at 12 and 24 months (coded by randomly assigned African American and European American coders); language abilities were assessed at 18, 24, 30, and 36 months. For receptive language, race was associated with ability level, and maternal sensitivity and negative-intrusive parenting were related to rate of growth. For expressive communication, race, SES, and maternal sensitivity were associated with rate of growth; race moderated the association between negative-intrusive parenting and rate of growth such that the relation was weaker for African American than for European American children. The results highlight the importance of sensitive parenting and suggest that the association between negative-intrusive parenting and language development may depend upon family context. Future work is needed concerning the race differences found, including examining associations with other demographic factors and variations in language input experienced by children, using culturally and racially validated indices of language development.