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Author Notes:

E-mail Address: dario@uchicago.edu.

The data analyses presented in this article were part of Hannah Koch's undergraduate honor's thesis at the University of Chicago.

She thanks Anne Henly and Bob Martin for advice on her thesis.

The authors also thank Richelle Scales and Anne Graff for technical assistance with the research procedures.

Conflicts of interest: nothing to declare.


Research Funding:

This research was supported by NIH grants R01-MH62577 and R01-HD06717 to D.M., R21-MH01005 to M.M.S., and RR-00165 to the Yerkes Center.


  • Science & Technology
  • Social Sciences
  • Life Sciences & Biomedicine
  • Developmental Biology
  • Psychology
  • stress
  • HPA axis
  • development
  • early experience
  • individual differences
  • rhesus monkeys

The Development of the Hypothalamic-Pituitary-Adrenal Axis in Rhesus Monkeys: Effects of Age, Sex, and Early Experience


Journal Title:

Developmental Psychobiology


Volume 56, Number 1


, Pages 86-95

Type of Work:

Article | Post-print: After Peer Review


We investigated the development of the HPA axis in group-living rhesus monkeys. Forty-three infants were studied from birth through their third year of life; 22 infants were physically abused by their mothers, while 21 infants were not abused. Plasma cortisol levels in basal conditions and in response to a novel environment test were assessed at 6-month intervals. Both basal and stress cortisol increased steadily from 6 to 24 months of age and then dropped. Across all ages, stress cortisol levels were significantly higher than the basal levels. The cortisol responses to stress at 30 and 36 months of age were significantly lower than the responses at all other ages. At most ages there was an inverse relationship between basal and stress cortisol levels. Individual differences in basal cortisol levels were generally stable in the first 2 years and more variable in the third year while the opposite for true for cortisol responses to stress. At the end of the first year, but not later in life, abused infants had higher cortisol levels than controls across the basal and stress conditions. Rates of social interactions with the mother and other group members were positively correlated with basal cortisol levels early in life, and with cortisol responses to stress later in life. Altogether, these results indicate that there are strong individual differences in HPA function, that there is a relationship between basal activity and stress reactivity, and that early abuse has the short-term effect of increasing both basal activity and stress reactivity.

Copyright information:

© 2013 Wiley Periodicals, Inc.

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