Structural magnetic resonance imaging demonstrates abnormal cortical thickness in Down syndrome: Newborns to young adults.

Down syndrome (DS) is a genetic disorder caused by an extra copy of all or part of chromosome 21 and is characterized by intellectual disability. We performed a retrospective analysis of 47 magnetic resonance imaging (MRI) examinations of participants with DS (aged 5 to 22 years) and compared them with a large cohort of 854 brain MRIs obtained from neurotypical participants (aged 5 to 32 years) with the objective of assessing the clinical presentation of Down syndrome, towards better understanding the neurological development associated with the condition. An additional cohort of 26 MRI exams from patients with DS and 139 exams from neurotypical participants (aged 0-5 years) are included as part of a supplementary analysis. Regionally distributed cortical thickness measurements, including average measurements as well as standard deviations (intra-regional cortical thickness variability) were extracted from each examination. The largest effect sizes observed were associated with increased average cortical thickness in the postcentral gyrus with specific abnormalities observed in Brodmann's areas 1 and 3b in DS, which was observed across all age ranges. We also observed strong effect sizes associated with decreased cortical thickness variability in the lateral orbitofrontal gyrus, the postcentral gyrus and more in DS participants. Findings suggest regionally irregular gray matter development in DS that can be detected with MRI.