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Development of cortisol circadian rhythm in infancy

Carolina de Weerth1, Robbert H Zijl, Jan K Buitelaar

  • 1Child and Adolescent Psychiatry, University Medical Center of Utrecht, HP A01.468-Postbox 85500, 3508 GA, Utrecht, The Netherlands. C.deWeerth@psych.azu.nl

Early Human Development
|August 23, 2003
PubMed

Insights

The diurnal cortisol rhythm emerges during infancy, with significant individual variability in its onset and stability. This variability, along with the chosen analysis method, impacts when the cortisol rhythm appears in infants.

Area of Science:

  • Endocrinology
  • Developmental Biology
  • Chronobiology

Background:

  • Cortisol, the final product of the hypothalamus-pituitary-adrenal (HPA) axis, is secreted with a circadian rhythm.
  • Infants acquire a cortisol circadian rhythm within their first year, but its onset age and relation to sleep-wake rhythms are debated.

Purpose of the Study:

  • To determine the age of appearance of the diurnal cortisol rhythm in infants.
  • To compare different analysis methods for assessing cortisol rhythm development.
  • To investigate the relationship between sleep-wake and cortisol circadian rhythms.

Main Methods:

  • Salivary cortisol levels were measured monthly in 14 infants from 2 to 5 months of age.
  • Data were analyzed using established methods and Multilevel Analysis (Hierarchical Linear Modeling).

Main Results:

  • Analysis methods yielded differing results for the age of cortisol rhythm appearance.
  • Significant individual differences were observed in the onset and stability of the diurnal cortisol rhythm.
  • A correlation was found between the emergence of sleep-wake and cortisol circadian rhythms.
  • High intraindividual variability in cortisol levels persisted even after accounting for confounding factors.

Conclusions:

  • The choice of statistical analysis method impacts the estimated age of cortisol rhythm onset.
  • Infants exhibit substantial individual variability in the development and stability of their cortisol circadian rhythm.
  • Hierarchical Linear Modeling highlighted the contribution of individual variability to differing study outcomes.
Abstract

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