The association of hypothalamic-pituitary-adrenal axis activity and blood pressure in an Afro-Caribbean population

Hyperactivity of the hypothalamic-pituitary-adrenal axis (HPAA) resulting from fetal programming may play a role in the development of high blood pressure (BP) in black people. We assessed the diurnal salivary cortisol profile in children with and without increased BP and evaluated their mother's HPAA. In a cross-sectional study, 20 Afro-Caribbean children (mean age 9.6 years) with higher blood pressures and 20 children with lower blood pressures were chosen from a prospective study of 569 mothers and children in Jamaica. Daytime salivary cortisol profiles were collected in the children and their mothers. The mothers were also assessed for features of the metabolic syndrome. Children with higher BP had higher mean morning salivary cortisol concentrations than those with lower BP (7.9 S.D. 1.9 vs. 4.5 S.D. 2.4nmol/l; p=0.03). Their mothers also had increased morning salivary cortisol concentrations (9.9 S.D. 1.8 vs. 5.5 S.D. 2.5nmol/l; p=0.02), but no changes in fasting glucose, insulin, lipids, BP or adiposity. Maternal and offspring cortisol concentrations correlated significantly (r=0.465, p=0.004). Maternal cortisol concentrations were significantly associated with the child's BP. We conclude that Afro-Caribbean children with higher BP have higher morning salivary cortisol concentrations. The children's cortisol concentrations correlate significantly with the mother's cortisol concentrations. These findings suggest that the HPAA may play a role in the development of raised BP in Afro-Caribbean people.