Background: Down syndrome (DS) is the most prevalent chromosomal disorder characterized by intellectual disability, multiple organ anomalies, generalized muscular hypotonia, and characteristic physical features. The presence of DS-associated medical comorbidities has contributed to brain morphologic changes. The aim of this study was to evaluate brain morphologic characteristics during infant and toddler ages in patients with DS using structural brain magnetic resonance imaging.
Methods: Structural brain T1-weighted magnetic resonance images from participants with DS with complete chromosome 21 trisomy (n = 20; 1.6 ± 0.6 [mean ± standard deviation] years old) were analyzed using FreeSurfer. The measurements were compared with those of 60 gender- and age-matched neurotypical controls by Cohen's d statistic and unpaired t test with false discovery rate correction for multiple comparisons and analyzed using a univariate general linear model with the following DS-associated medical comorbidities: congenital cardiac disease, infantile spasms, and hypothyroidism.
Results: We identified 27 candidate measurements with large effect sizes (absolute d > 0.8) and statistically significant differences (P < 6.9 × 10-3). Among them were decreased volumes in bilateral cerebellar gray matter and right cerebellar white matter and brainstem and cortical abnormalities in the right superior temporal, right rostral anterior cingulate, and left rostral middle frontal gyrus, independent of comorbid effects. Only bilateral cerebellar gray matter volumes and brainstem volume showed differences between DS and healthy groups during infancy.
Conclusion: These results suggest that cerebellar gray matter and brainstem may represent the primary regions affected by the presence of an additional copy of chromosome 21.
Keywords: Brain morphology; Brainstem; Cerebellum; Epilepsy; Hypothyroidism.
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