Early White Matter Microstructure Alterations in Infants with Down Syndrome.

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• Down syndrome (DS), caused by Trisomy 21, is the most common chromosomal disorder and a primary cause of intellectual disability.
• While its impact on brain development is known, early white matter (WM) microstructure in infants with DS is under-researched.
• Previous studies show reduced WM integrity in older individuals with DS, but not in infancy.

Purpose of the Study:

• To investigate early white matter (WM) microstructure in infants with Down syndrome (DS).
• To utilize advanced neuroimaging techniques, Diffusion Tensor Imaging (DTI) and Neurite Orientation Dispersion and Density Imaging (NODDI), for detailed analysis.
• To identify specific patterns of WM alterations in infants with DS.

Main Methods:

• Recruited 49 infants with DS and 36 typically developing controls, all scanned at 6 months of age.
• Employed Diffusion Tensor Imaging (DTI) to assess white matter integrity.
• Utilized Neurite Orientation Dispersion and Density Imaging (NODDI) to examine neurite density and dispersion.

Main Results:

• Infants with DS exhibited significantly reduced fractional anisotropy and neurite density index in key association tracts like the inferior fronto-occipital fasciculus and superior longitudinal fasciculus II.
• Increased radial diffusivity, indicative of disrupted myelination, was observed in these tracts.
• Elevated orientation dispersion index in several tracts suggested increased neurite dispersion and fanning in infants with DS.

Conclusions:

• Early infancy reveals widespread white matter (WM) microstructural developmental alterations in Down syndrome (DS).
• Findings highlight reduced structural integrity, neurite density, and altered myelination in infants with DS.
• These insights into early neurodevelopment in DS may guide the timing of therapeutic interventions.