TABLE 3.

Main diffusion magnetic resonance imaging (MRI) findings in DS by age and diagnostic groups.

Age/Diagnostic groups	Mian diffusion MRI findings	References
Children/teenagers DS	Underdevelopment of projection fibres, such as anterior thalamic radiation, Internal capsule, cerebral and cerebellar peduncles, as well as pontine-cerebellar and olivo-cerebellar pathways. Furthermore, one study evidenced underdevelopment of the IFOF, ILF, UF.	Gunbey et al., 2017; Lee et al., 2020
Adult DS	All the main long association fibres and the corpus callosum are affected. Moreover, some studies evidenced reduced microstructural integrity of the anterior thalamic radiation and corticospinal tract.	Powell et al., 2014; Fenoll et al., 2017; Romano et al., 2018; Patrick et al., 2019; Bazydlo et al., 2021
DS with preclinical/prodromal AD	FA reduction of all the main long association fibres and the corpus callosum when compared to healthy adults with DS. FA of cingulum bundle, splenium of corpus callosum, ILF, and UF can distinguish DS with preclinical/prodromal AD from healthy DS	Rosas et al., 2020
DsAD	FA reduction of all the main long association fibres and the corpus callosum when compared to healthy adults with DS	Patrick et al., 2019; Rosas et al., 2020; Bazydlo et al., 2021

DS, Down syndrome; DsAD, Down syndrome with Alzheimer disease; IFOF, inferior fronto-occipital fasciculus, ILF, inferior longitudinal fasciculus; SLF, superior longitudinal fasciculus; UF, uncinate fasciculus.