Cognitive development in children born preterm: implications for theories of brain plasticity following early injury.

The human brain is functionally altered through experience, a phenomenon known as plasticity. Relevant experiences may be negative, as in brain injury. Adult brain injury results in permanent impairment. However, it has been assumed that early injury leads to substantial functional recovery. Animal studies suggest several predictions regarding whether this principle generally holds true. These studies indicate that the timing of brain injury, relative to the expected course of neurodevelopment, impacts the extent of recovery. Injuries occurring during the period of cell migration are particularly detrimental. However, outcome must be assessed longitudinally because apparent recovery in childhood may reverse as the brain matures. Moreover, recovery of one function may come at the expense of others. Whether these findings characterize outcome following preterm birth is the focus of this review. Preterm birth is associated with high rates of neurodevelopmental disability, primarily due to hypoxic-ischemic events. Periventricular brain structures and white matter tracts are particularly vulnerable to damage. Through school age, preterm children exhibit diminished levels of global intellectual function, attention, memory, and reasoning skills relative to full-term peers. It is questionable whether these deficits persist. Because few studies have followed recent cohorts into young adulthood, it is argued that outcome cannot be reliably described based on the available literature. Moreover, important contributors to later development have been neglected, including both genetic and experiential factors. With improved assessment, it may be possible to develop interventions based on the individual child's constellation of genetic, biological, and sociodemographic risks.