Abstract

Objective: This observational cohort study addressed the hypothesis that after preterm delivery brain growth between 24 and 44 weeks postmenstrual age (PMA) is related to global neurocognitive ability in later childhood. Methods: Growth rates for cerebral volume and cortical surface area were estimated in 82 infants without focal brain lesions born before 30 weeks PMA by using 217 magnetic resonance images obtained between 24 and 44 weeks PMA. Abilities were assessed at 2 years using the Griffiths Mental Development Scale and at 6 years using the Wechsler Preschool and Primary Scale of Intelligence–Revised (WPPSI-R), the Developmental Neuropsychological Assessment (NEPSY), and the Movement Assessment Battery for Children (MABC). Analysis was by generalized least-squares regression. Results: Mean test scores approximated population averages. Cortical growth was directly related to the Griffiths Developmental Quotient (DQ), the WPPSI-R full-scale IQ, and a NEPSY summary score but not the MABC score and in exploration of subtests to attention, planning, memory, language, and numeric and conceptual abilities but not motor skills. The mean (95% confidence interval) estimated reduction in cortical surface area at term corrected age associated with a 1 SD fall in test score was as follows: DQ 7.0 (5.8–8.5); IQ 6.0 (4.9–7.3); and NEPSY 9.1 (7.5–11.0) % · SD−1. Total brain volume growth was not correlated with any test score. Conclusions: The rate of cerebral cortical growth between 24 and 44 weeks PMA predicts global ability in later childhood, particularly complex cognitive functions but not motor functions. During late fetal life, brain growth is rapid, particularly in the cerebral cortex. In infants born preterm, the reduced growth of the cortical surface area relative to total brain volume correlates with lower postmenstrual age (PMA) at birth and a lower Griffiths Developmental Quotient (DQ) at 2 years of age.1 Preterm birth also leads to local changes in brain volume2 and perhaps to a reduction in total brain volume, although this is controversial.3,4 These data raised the hypothesis that brain growth in the perinatal period, particularly of the cerebral cortex, predicts later neurocognitive function in infants born preterm. To address this, we examined childhood abilities in a cohort of infants in whom growth of the cortical surface area and cerebral volume between 24 and 44 weeks PMA had been measured.