MAPT and Alzheimer disease: The presence of AD pathology in DS is similar to sporadic AD; however, the accumulation of amyloid beta (Aβ) brain plaques occurs several decades earlier,5, 6, 7, 8 followed by the presence of neurofibrillary tau tangles (NFTs),9, 10, 11, 12 and then neurodegeneration as evidenced by hippocampal atrophy, altered glucose metabolism, and increased glial fibrillary acidic protein levels.13, 14