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Stress Effects on the Developing Brain 137emotion systems among children who have experienced failures of the caregivingsystem early in life? The answers to these questions are just beginning to emergeand are likely to be qualified by individual differences among children reflectinginherited genetic vulnerabilities. I will deal first with the emerging literature onwhether it matters to human development and, if so, how. Then I will turn to thevery nascent intervention research.The does-it-matter question has two parts. Part one involves whether early experiencesshape reactivity of the HPA axis and/or the functioning of the stressemotionsystem. Part two involves whether these alterations predict children’sphysical and mental health. Unfortunately, to date, nearly all of our informationabout whether it matters comes from studies that have only indirectly measuredthe patterns of care children received early in development. Nonetheless, the resultsof this work are suggestive. One of the most interesting findings comes bywork of Essex and colleagues (Essex, Klein, Cho, & Kalin, 2002). They followeda large cohort of families recruited during pregnancy with the goal of examininghow families balanced work and family life. When the children were 4.5 yearsold, measures of cortisol were obtained in the late afternoon at home over severaldays. These researchers found that maternal stress during the child’s infancy combinedwith her stress when the child was 4 predicted child cortisol levels. Specifically,maternal stress at age 4 did not produce elevated child cortisol levels, unlessthe mother was also highly stressed during the child’s infancy. The authors arguedthat maternal stress during her child’s infancy impacted her parenting andshaped an HPA system in the child that was more reactive to stress—hence, thechild’s response to maternal stress at age 4. Notably, among their indices of maternalstress, it was maternal depression that accounted for the child cortisol finding.This is consistent with work by Lupien and colleagues (Lupien, King, Meaney,& McEwen, 2000). They studied school-aged children when the children arrivedat school in the morning. Higher cortisol levels were observed among childrenwhose mothers reported more symptoms of depression.Maternal depression has been the focus of a number of studies as it is associatedwith heightened risk for a variety of poor outcomes in children, includingboth anxiety/depression and delinquency/aggression (see review, Downey &Coyne, 1990). Children of depressed mothers tend to show more right-sided frontalEEG patterns, associated with withdrawal emotions (sadness, fear, anxiety), andthey also exhibit higher cortisol levels at home during the preschool period(Dawson & Ashman, 2000). The higher preschool-aged cortisol levels were associatedwith maternal depression in the child’s first year of life more so than themother’s depressive episodes after the child’s infancy. This same research group,however, failed to find direct associations with early maternal depression whenthey saw the children for laboratory testing at age 7 (Ashman, Dawson, Panagiotides,Yamada, & Wilkinson, 2002). Instead, at 7 years, HPA axis responsivityappeared to be a joint function of the mother’s earlier depressive episodes and the