Lab-based experimental studies with humans and in animal models demonstrate that the relation between glucocorticoid (GC) levels and performance on measures of higher-order cognitive ability such as executive function (EF) is best described by an inverted U-shape curve. Moderate levels of GCs (cortisol/corticosterone) are associated with comparatively better performance relative to GC levels that are particularly high or low. Although findings from experimental studies are definitive and have high internal validity, the external validity of this association as an aspect of children's development is unknown. Here we analyze data from the Family Life Project (N = 1292), a prospective longitudinal sample of children and families in predominantly low-income and rural communities followed longitudinally from infancy through age 60 months. Consistent with the prior experimental literature, we found evidence of an inverted-U relation. For children with relatively low cortisol levels, on average, between the ages 7, 15, 24, and 48 months, those illustrating moderate fluctuations in their cortisol levels over this span tended to show subsequently better EF performance at 60 months, than did children with either highly stable or highly variable temporal profiles. This curvilinear function did not extend to children whose cortisol levels were high, on average. These children tended to show lower EF performance, irrespective the stability of their cortisol levels over time.
Bibliographical noteFunding Information:
We thank the many families and research assistants that made this study possible. Support for this research was provided by the National Institute of Child Health and Human Development grants R01 HD51502 and P01 HD39667 with co-funding from the National Institute on Drug Abuse. The Family Life Project Key Investigators include Lynne Vernon-Feagans, The University of North Carolina, Mark Greenberg, The Pennsylvania State University, Martha Cox, The University of North Carolina, Clancy Blair, New York University, Peg Burchinal, The University of North Carolina, Michael Willoughby, The University of North Carolina, Patricia Garrett-Peters, The University of North Carolina, Roger Mills-Koonce, The University of North Carolina, Maureen Ittig, The Pennsylvania State University.
- Early childhood
- Executive functions