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.