Vulnerability of the developing brain - Neuronal mechanisms

About 300,000 low birth weight neonates are born in the United States each year [1], and 60,000 of them are classified as very low birth weight (< 1500 g). An overwhelming majority of these children are born preterm, at a time when the brain's architecture and vasculature have not developed completely. The percentage of low birth weight and very low birth weight babies has increased gradually in the last 20 years, with a concurrent decline in neonatal and infant mortality rates (Fig. 1). It has been suggested that this decline in mortality rates could be the result of improved obstetric and neonatal care [1]. Despite impressive achievements in the increasing survival of this population, parents and teachers may be dismayed to find a high prevalence of cognitive deficits, learning difficulties, and abnormal behaviors during their early childhood and primary school years. Multiple follow-up studies of ex-preterm neonates have reported a high prevalence of major neurodevelopmental deficits [2-4], with lifetime needs for special assistance [5] and increasing burdens on the annual health care budget [6].