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Cortisol release in infants in response to inoculation
1Institute for the Study of Child Development, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick 08903.
Insights
Infant inoculation triggers a significant cortisol stress response. Basal cortisol levels and circadian rhythms influence stress reactivity, requiring careful consideration in infant stress studies.
Area of Science:
- Pediatric endocrinology
- Developmental psychology
- Stress physiology
Background:
- Infant stress responses are critical for development.
- Salivary cortisol is a key biomarker for physiological stress.
- Understanding infant stress requires accounting for multiple factors.
Purpose of the Study:
- To examine salivary cortisol changes in infants following inoculation.
- To investigate the relationship between basal cortisol, behavioral responses, and stress reactivity.
- To explore the influence of circadian rhythms on infant cortisol levels.
Main Methods:
- Cross-sectional study design.
- Salivary cortisol measurements in infants aged 2, 4, and 6 months.
- Data collection pre- and post-inoculation, with behavioral observation.
Main Results:
- Cortisol levels significantly increased after inoculation.
- Behavioral responses correlated with cortisol release patterns.
- Lower basal cortisol predicted a larger cortisol increase.
- A circadian rhythm in basal cortisol emerged by 6 months.
Conclusions:
- Infant stress responses are influenced by basal cortisol levels and circadian rhythms.
- Accurate assessment of infant stress requires consideration of these factors.
- Appropriate statistical methods are essential for analyzing infant stress data.
Abstract:
Using a cross-sectional design, salivary cortisol was obtained from infants aged 2, 4, and 6 months, prior to and 15 min following an inoculation. Cortisol rose significantly following inoculation. Behavioral responses to inoculation were consistent with the observed patterns of cortisol release. Cortisol base level was significantly and negatively related to the cortisol change score. At 6 months the basal levels also were influenced by an adult-like circadian rhythm; infants tested shortly after awakening had higher basal levels than those tested later in the day. These data provide strong evidence that studies of stress and cortisol release in infants must be sensitive to basal level, circadian rhythm, and behavioral effects, and that appropriate statistical procedures should be employed.