Dampening of Adrenocortical Responses during Infancy: Normative Changes and Individual Differences

Abstract

Changes in cortisol and behavioral responses were examined longitudinally in 83 infants (39 girls, 44 boys) tested at their well-baby exams with inoculations at 2, 4, 6, and 15 months (72 infants completed all testing). Another sample of 2-, 4-, and 6-month-olds (n = 18 per age) received mock exams without inoculations to determine early developmental changes to the exam procedures. Behavioral distress was coded every 30 sec during the exam, a 5-min inoculation period, and a 20-min recovery period. Salivary cortisol was obtained upon arrival at the clinic and 25 min after the beginning of the inoculation period. To the exam-inoculation procedures, cortisol responses were high at 2 months, decreased significantly between 2 and 4 months, remained comparable between 4 and 6 months, and then declined again between 6 and 15 months. Between 6 and 15 months there was also a decrease in pretest cortisol. By 15 months, significant increases in cortisol from pre- to posttest were no longer observed for most infants. To the exam-only procedures, cortisol responses decreased between 2 and 4 months, and by 4 months most infants failed to show pre- to posttest increases in cortisol. Behavioral distress decreased between 2 and 6 months, but increased again at 15 months. While crying and cortisol were modestly correlated during the 2- to 6-month exam-inoculation procedures, at 15 months no significant correlations were obtained. Behavioral and hormonal reactions thus followed different ontogenetic paths and may provide different information about infant functioning. There was some evidence that the emergence of the circadian rhythm in cortisol might be related to the early decrease in cortisol response.

The developmental course of salivary alpha-amylase and cortisol from 12 to 36 months: Relations with early poverty and later behavior problems

“…These results extend previous cross-sectional research showing that baseline cortisol levels at 12, 18 and 24 months were higher than those observed at 30 and 36 months (Watamura et al, 2004). These results are also broadly consistent with findings reported by Gunnar et al (1996) and others (Nachmias et al, 1996) that documented decreases in baseline cortisol in early childhood.…”

Infant Stress and Parent Responsiveness: Regulation of Physiology and Behavior During Still‐Face and Reunion

“…In addition, prior still-face studies evaluating heart rate and behavior examined infants at 5 months (Bazhenova et al, 2001) and 6 months (Weinberg & Tronick, 1996). In addition, infants of this age elicit cortisol responses to social challenges (Gunnar, Broderson, Krueger, & Rigatuso, 1996;Lewis & Ramsay, 1995).…”

Behavioral and Physiological Responsivity, Sleep, and Patterns of Daily Cortisol Production in Infants with and without Colic

“…The examination procedures were organized into two sets designed to be increasingly challenging and invasive. These sets were modeled after a typical well-baby examination on the basis of previous data showing that such procedures elicit behavioral distress and elevate salivary cortisol concentrations in infants of this age (Gunnar, Brodersen, Krueger, & Rigatuso, 1996). The first stressor set-Measurement-lasted 6 to 8 min ( M ϭ 8 min) and consisted of the parent undressing the infant and the researcher taking ear temperature, weight, length, and head circumference followed by a 2-min soothing protocol.…”