Abstract
Developmental language disorder is a highly common yet underdiagnosed neurodevelopmental disorder which impacts receptive and/or expressive language abilities and cannot be attributed to another etiology such as hearing loss or a lack of early exposure to language. There is very little research into the brain differences that characterize developmental language disorder, especially in adult populations In this study, we used diffusion MRI to determine whether adults with DLD show differences in white matter microstructure of the brain when compared to adults with typical language. Participants included 23 adults identified as meeting criteria for developmental language disorder, as well as a group of 26 adults with typical language. White matter microstructure was examined with fractional anisotropy via diffusion tensor imaging and precise biophysical models of intra-axonal signal fraction and orientation coherence via the Standard Model of diffusion imaging, using tractometry to evaluate microstructure differences along white matter tracts. Analysis showed reduced myelin integrity in DLD in the corpus callosum, but increased myelin integrity in the left superior longitudinal fasciculus. It is yet unclear whether differences exist in childhood and are retained into adulthood, are a result of different language environments during childhood, or are a result of behavioral and neural compensation.