Corpus callosum structural characteristics in very preterm children and adolescents: developmental trajectory and relationship to cognitive functioning

The corpus callosum is the largest white matter commissural pathway, important for inter-hemispheric communication. Previous studies suggest that structural alteration of the corpus callosum occurs after a preterm birth in the neonatal period that lasts across childhood, adolescence and young adulthood. The present study aims to unravel corpus callosum structural characteristics across development in very preterm children and adolescents aged 6 to 15 years, as well their associations with general intellectual, executive and social functioning. Neuropsychological assessments of general intellectual, executive and social functioning as well as T1-weighted and multi-shell diffusion MRI were collected in 79 very preterm and 46 full term controls aged 6 to 15 years. Volumetric, diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) measures were extracted on 7 portions of the corpus callosum using TractSeg. A multivariate data-driven approach (partial least squares correlation) and an age normative modelling approach were used to explore associations between callosal characteristics and neuropsychological outcomes. The very preterm and full-term control group showed similar trends of white-matter maturation over time, i.e., increase FA and reduced ODI, in all segments of the corpus callosum, that was associated with increase in general intellectual functioning. However, using age-related normative modelling of volumetric, tensor and NODDI diffusion measures, findings show atypical pattern of callosal development in the very preterm group with reduced callosal maturation over time. Atypical developmental trajectory of callosal maturation was associated with poorer general intellectual and working memory functioning as well as with greater prematurity. The present study also illustrates how normative age modelling approach allows to shed new insight into neurodevelopmental trajectory in the VPT population and its association with functional outcomes.