How children cope with stressful events is an important subject in child development and pediatric medicine. Although most work on childhood stress is behavioral,1 growing evidence that chronic stress is related to a variety of childhood illnesses2 makes it imperative that we understand the relations between children's behavioral and physiologic responses. The focus of the research covered in this manuscript is activity of the hypothalamic-pituitary-adrenocortical (HPA) system. Since Hans Selye's3 initial formulations of the stress concept, activity of this neuroendocrine system has been viewed as almost synonymous with the term stress. The work on human adults and infrahuman species shows that this system plays a central role in stress resistance, although the mechanisms are not fully understood.4,5 With the exception of our own work, there has been little systematic hormone-behavior research on this system in healthy, normal children. However, the recent modification of radioimmunoassays to allow assessment of cortisol levels in small samples of saliva is altering this picture, and researchers are now including salivary cortisol level in their research as one of a number of indices of emotional distress. The results of this recent work indicate that elevations in cortisol appear to be part of the biologic cost of adaptive functioning, a conclusion consistent with previous work in animals and adults.3 Furthermore, increases in cortisol level frequently correlate with children's active and appropriate attempts to cope with potentially distressing circumstances.
DESCRIPTION, RATIONALE, AND MEASUREMENT
Cortisol is the primary glucocorticoid of the HPA system in humans. Organisms deprived of cortisol can survive in protected environments, but without replacement hormones they cannot tolerate even the normal physical and emotional perturbations of daily life.6