Long-term stability of cortisol production and metabolism throughout adolescence: longitudinal twin study

Life-course experiences have been postulated to program hypothalamus-pituitary-adrenal (HPA) axis activity, suggesting that HPA axis activity is, at least partially, stable over time. Yet, there is paucity of data on the long-term stability of cortisol production and metabolism. We performed a prospective follow-up study in twins recruited from a nationwide register to estimate the stability of cortisol production and metabolism over time, and the contribution of genetic and environmental factors to this stability. In total, 218 healthy mono- and dizygotic twins were included. At the ages of 9, 12 and 17 years, morning urine samples were collected for assessment (by gas chromatography-tandem mass spectrometry) of cortisol metabolites, enabling the calculation of cortisol metabolite excretion rate and cortisol metabolism activity. Our results showed a low stability for both cortisol metabolite excretion rate (with correlations <.20) and cortisol metabolism activity indices (with correlations of .25 to .46 between 9 and 12 years, -.02 to .15 between 12 and 17 years and .09 to .28 between 9 and 17 years). Because of the low stability over time, genetic and environmental contributions to this stability were difficult to assess, although it seemed to be mostly determined by genetic factors. The low stability in both cortisol production and metabolism between ages 9 and 17 years reflects the dynamic nature of the HPA axis

Long-Term Neurodevelopmental and Functional Outcomes of Infants Born Very Preterm and/or with a Very Low Birth Weight

Background: Birth weight (BW) is often used as a proxy for gestational age (GA) in studies on preterm birth. Recent findings indicate that, in addition to perinatal outcomes, subjects born very preterm (VP; GA <32 weeks) differ from those with a very low birth weight (VLBW; BW <1,500 g) in postnatal growth up to their final height. Objective: To study whether neurodevelopmental and functional outcomes at the age of 19 years differ in VP and/or VLBW subjects. Methods: 705 19-year-old subjects from the Project on Preterm and Small-for-Gestational-Age Infants (POPS) cohort were classified as (1) VP+/VLBW+ (n = 354), (2) VP+/VLBW– (n = 144), or (3) VP–/VLBW+ (n = 207), and compared with regard to IQ as assessed with the Multicultural Capacity Test-intermediate level; neuromotor function using Touwen’s examination of mild neurologic dysfunction; hearing loss; self- and parent-reported behavioral and emotional functioning; educational achievement and occupation; and self-assessed health using the Health Utilities Index and the London Handicap Scale. Results: VP+/VLBW– infants, on average, had 3.8-point higher IQ scores (95% confidence interval [CI] 0.5– 7.1), a trend towards higher educational achievement, 3.3- dB better hearing (95% CI 1.2–5.4), and less anxious behavior, attention problems, and internalizing behavior than to VP+/VLBW+ subjects. VP–/VLBW+ infants reported 1.8 increased odds (95% CI 1.2–2.6) of poor health compared to VP+/VLBW+ subjects. Conclusions: At the age of 19 years, subjects born VP+/VLBW+, VP+/VLBW–, and VP-/VLBW+ have different neurodevelopmental and functional outcomes, although effect sizes are small. Hence, the terms VP and VLBW are not interchangeable. We recommend, at least for industrialized countries, to base inclusion in future studies on preterm populations on GA instead of on B

Breast-Milk Cortisol and Cortisone Concentrations Follow the Diurnal Rhythm of Maternal Hypothalamus-Pituitary-Adrenal Axis Activity

Very preterm infants often receive donor milk from mothers who deliver at term, but its composition differs from that of their own mother's milk. Because breast-milk glucocorticoids can support developing neonates, we explored concentration variability within and between mothers. We hypothesized that breast-milk glucocorticoid concentrations would be higher after very preterm delivery [gestational age (GA) <32 wk; study 1] and would follow the diurnal rhythm of maternal adrenocortical activity (study 2). Study 1 assessed differences in milk cortisol, cortisone, and the cortisone-to-(cortisol+cortisone) ratio of mothers who delivered at (median) GA: 28.6 wk or at term weekly during the first month postpartum. Study 2 assessed variations in milk cortisol, cortisone, and the cortisone-to-(cortisol+cortisone) ratio over 24 h, and tested Pearson correlations between milk and salivary concentrations in mothers who delivered at term (median GA: 38.9 wk) during week 4 postpartum. In these studies, foremilk glucocorticoids were measured by liquid chromatography-tandem mass spectrometry. Associations of milk cortisol, milk cortisone, and the milk cortisone-to-(cortisol+cortisone) ratio with prematurity (study 1) or collection time (study 2) were studied with longitudinal data analyses. In study 1, giving birth to a very preterm infant was associated with reductions in milk cortisol and cortisone concentrations of 50% (β: 0.50; 95% CI: 0.26, 0.99; P = 0.05) and 53% (β: 0.53; 95% CI: 0.30, 0.93; P = 0.03), respectively, when adjusted for collection time. In study 2, concentrations of milk cortisol and cortisone were associated with collection time (both P <0.01), peaking at ∼0700. Milk and salivary concentrations of cortisol (r = 0.92, P <0.01) and cortisone (r = 0.93, P <0.01) as well as the cortisone-to-(cortisol+cortisone) ratio (r = 0.64, P <0.01) were correlated with one another. Breast-milk glucocorticoid concentrations follow the diurnal rhythm of maternal hypothalamus-pituitary-adrenal axis activity and are lower in mothers who deliver very preter