The neuroendocrine system following preterm birth and its effects on cognitive and brain development at age 7

© 2012 Dr. Shannon Elizabeth ScratchPreterm birth is associated with a well-defined pattern of neurodevelopmental impairments which include a range of cognitive deficits, as well as structural brain abnormalities. Further, preterm infants are known to have a transiently altered neuroendocrine system during the first weeks of postnatal life. Although recent studies have focused on characterising long-term neurobehavioural deficits, few have examined potential mechanisms that may, at least partly, explain these poorer outcomes. This study aimed to address this shortcoming by focusing on the postnatal neuroendocrine system and its association with neurodevelopmental outcomes at age 7 in a group of children born very preterm. Postnatal concentrations of three hormones, free thyroxine, cortisol, and growth hormone, were examined using both direct hypothesis testing and exploratory hypothesis-generating approaches. Three direct hypotheses were proposed following review of the literature. Firstly, it was hypothesised that lower postnatal free thyroxine concentrations would be associated with poorer performances on measures of intellect, attention, and visuoperceptual abilities, as well as reductions in grey and white matter volumes at age 7 in children born very preterm. Secondly, it was hypothesised that higher postnatal cortisol concentrations would be associated with poorer performances on tasks of new learning and memory and volumetric reductions in the hippocampi at age 7 in children born very preterm. The final hypothesis predicted that elevated postnatal growth hormone concentrations would be related to deficits in attention and executive functioning and reductions in the prefrontal brain volumes at age 7 in children born very preterm. The current study investigated 83 children born very preterm (gestational age <30 weeks and/or birth weight