Growth of the corpus callosum in adolescents born preterm.

OBJECTIVE To examine the growth of the corpus callosum between adolescence and early adulthood in individuals who were born before 33 weeks' gestation (very preterm [VPT]) and its relation to neuropsychological function. DESIGN A longitudinal cohort study of VPT individuals born between January 4, 1982, and December 29, 1984, and a term-born comparison group. SETTING A long-term follow-up study into perinatal predictors of outcome after preterm birth at University College Hospital, London. PARTICIPANTS A total of 72 VPT and 34 term-born individuals were assessed in adolescence (aged 15 years) and in early adulthood (aged 19 years). Adult assessments took place between June 6, 2002, and October 23, 2004. MAIN EXPOSURE Birth before 33 weeks' gestation. OUTCOME MEASURE The cross-sectional area of 4 segments of the corpus callosum, measured on the midsagittal slice of high-resolution structural magnetic resonance images in adolescence and young adulthood. RESULTS Total corpus callosum size increased in term and VPT groups, but growth was much greater in the VPT group (13.4% in the VPT group vs 3.3% in the term group). There were significant associations between adult performance IQ and growth of anterior (P = .001), midposterior (P = .009), and posterior (P = .009) segments in the VPT group. CONCLUSIONS The corpus callosum grows dramatically in VPT adolescents, and this growth is associated with neuropsychological outcome. This may represent a delay of a normal maturational process in VPT individuals.