Hypocortisolism in the form of low early morning cortisol levels has been found in a number of studies of children who have experienced conditions of chronic deprivation and neglect (see review, Gunnar and Vazquez, 2001). For example, a study involving infants in foster care revealed low early morning cortisol levels in these children relative to non-maltreated infants from families of similar socioeconomic standing (Dozier et al., 2006). Even lower early morning cortisol levels and atypical patterns of cortisol production over the day have been reported for toddlers in institutional care in Romania (Carlson and Earls, 1997). These results were similar to findings noted by both Gunnar and colleagues’ small study of post-institutionalized infants assessed 2 months post-adoption (Bruce et al., 2000) and Fisher and colleagues’ study of preschoolers entering a new foster placement (Bruce, Fisher et al., 2009). In all these studies, 30–40% of the children had early morning cortisol levels that were one standard deviation or more below the mean of children who had not experienced ELS.
