A negative association between functional profiles in multiple cognitive domains and cortical thickness in Down...

People with Down syndrome (DS) have intellectual disability and a distinct neuroanatomy due to genetic-induced atypical neurodevelopment. Although a few previous studies have shown increased cortical thickness (CT) in this syndrome, their functional impact remains to be investigated. Here we addressed this question by studying structure-behaviour associations to better understand how regional neuroanatomical profiles in individuals with DS relate to their cognitive functioning.

Structural T1-weighted MRI imaging was performed on 17 young adults non-demented participants with DS (mean age 29 ± 7.84 years), and 19 age- and sex-matched typically developed (TD) controls. CT measurements were conducted using the CAT12 SPM toolbox, which was also used to perform between-group comparisons of the CT maps. We then investigated in the group of individuals with DS the association between CT and their performance on verbal comprehension, perceptual organization, processing speed indices provided by the WAIS-III, by computing vertex-wise multiple linear regressions.

Between-group comparisons of the morphological data showed a significantly (q < 0.05, FDR corrected) enlarged frontal, occipitoparietal cortex, and dorsal posterior cingulate areas but reduced ventral posterior cingulate and precentral gyrus in individuals with DS. Cognitive performance in verbal, perceptual and speed processing domains was negatively associated with CT increments in several brain regions previously implicated in these functions.

An abnormally thicker cortex in young non-demented adults with DS appears to have a detrimental effect on cognitive functioning, as suggested by the negative correlation between cognitive performance and regional cortical thickness.