Differences in cortical surface area in developmental language disorder
Approximately seven per cent of children have developmental language disorder (DLD), a neurodevelopmental condition associated with persistent language learning difficulties without a known cause. Our understanding of the neurobiological basis of DLD is limited. Here, we used FreeSurfer to investigate cortical surface area and thickness in 54 children and adolescents with DLD and 74 age-matched controls aged 10-16 years. We also examined cortical asymmetries in DLD using an automated surface-based technique. Those with DLD showed smaller surface area bilaterally in the inferior frontal gyrus extending to the anterior insula, in the posterior temporal and ventral occipito-temporal cortex, and in portions of the anterior cingulate and superior frontal cortex. There were no differences in cortical thickness, nor in asymmetry of these cortical metrics. Post-hoc exploratory analyses revealed that surface area in the left fusiform and inferior frontal cortex related to childrens reading and non-word repetition scores, respectively. This study highlights the importance of distinguishing between surface area and cortical thickness in investigating the brain basis of neurodevelopmental disorders and suggests the development of cortical surface area to be of importance to DLD. Future longitudinal studies are required to understand the developmental trajectory of these cortical differences in DLD and how they relate to language maturation.