Hair cortisol concentration, a biomarker of chronic stress, is associated with early breast development in girls and increased testicular volume in boys.
Scientists are trying to understand how childhood adversity affects puberty, but linking the two is difficult. Hair cortisol concentration (HCC) is a potentially useful biological marker of chronic stress. However, previous studies were unable to link childhood adversity to puberty in boys.
Research published in JAMA Pediatrics by Ying Sun and colleagues examined HCC and pubertal development in 1263 elementary school-aged children (age range 6.4 – 9.9 years) in China. Cortisol was extracted from hair samples and measured using a commercially available cortisol test kit. For girls, breast development was assessed by the same pediatric endocrinologist using Breast Tanner stages, a scale of physical development. For boys, a Prader orchidometer was used to estimate testicular volume. The study found no difference in cortisol levels between boys and girls. Early breast development was significantly higher for girls with the HCC levels in the third and fourth quartile compared to those with lower HCC levels. Overall, the investigators found a 2.5-fold increase in the risk of early breast development in girls in the highest quartile of HCC compared to those in the lowest quartile. Similarly, testicular volume in boys was significantly correlated (p< .001) with HCC, those with higher levels of HCC had larger mean testicular volumes. A 0.12-milliliter increase in testicular volume was observed with each quartile increase in HCC in boys.
This is the first study to measure the cortisol level in hair of children in relation to puberty. Scientists hope that additional studies will help us better understand the timing of puberty and how chronic stress increases the risk of early puberty.
Written By: Cindi A. Hoover, Ph.D.