Myelination of Preterm Brain Networks at Adolescence

Abstract

Prematurity and preterm stressors severely affect the development of infants born before 37 weeks of gestation, with increasing effects seen at earlier gestations. Although preterm mortality rates have declined due to the advances in neonatal care, disability rates, especially in middle-income settings, continue to grow. With the advances in MRI imaging technology, there has been a focus on safely imaging the preterm brain to better understand its development and discover the brain regions and networks affected by prematurity. Such studies aim to support interventions and improve the neurodevelopment of preterm infants and deliver accurate prognoses. Few studies, however, have focused on the fully developed brain of preterm born infants, especially in extremely preterm subjects. To assess the long-term effect of prematurity on the adult brain, myelin related biomarkers such as myelin water fraction and g-ratio are measured for a cohort of 19-year-old extremely preterm subjects. Using multi-modal imaging techniques that combine T2 relaxometry and neurite density information, the results show that specific regions of the brain associated with white matter injuries due to preterm birth, such as the Posterior Limb of the Internal Capsule and Corpus Callosum, are still less myelinated in adulthood. Such findings might imply reduced connectivity in the adult preterm brain and explain the poor cognitive outcome.