Structural abnormalities of the corpus callosum (CC), such as reduced size and increased shape variability, have been documented in individuals with fetal alcohol spectrum disorders (FASD). However, the regional specificity of altered CC structure, which may point to the timing of neurodevelopmental disturbances and/or relate to specific functional impairments, is unclear. Further, associations between facial dysmorphology and callosal structure remain undetermined.
153 participants (age range 8–16) including 82 subjects with FASD and 71 non-exposed controls were included in this study. The structural magnetic resonance imaging (sMRI) data of these subjects was collected at 3 sites (Los Angeles and San Diego, California, and Cape Town, South Africa) and analyzed using classical parcellation schemes as well as more refined surface based geometrical modeling methods to identify callosal morphological alterations in FASD at high spatial resolution.
Reductions in callosal thickness and area, specifically in the anterior third and the splenium, were observed in FASD compared to non-exposed controls. In addition, reduced CC thickness and area significantly correlated with reduced palpebral fissure length.
Consistent with previous reports, findings suggest an adverse effect of prenatal alcohol exposure on callosal growth and further indicate that fiber pathways connecting frontal and parieto-occipital regions in each hemisphere may be particularly affected. Significant associations between callosal and facial dysmorphology provide evidence for a concurrent insult to midline facial and brain structural development in FASD.