Semiquantitative scales and quantitative computerized image analyses were used to determine the neurofibrillary tangle formation and AB amyloid deposition in the hippocampal formation and inferior temporal gyrus in 36 Down’s syndrome cases, aged 4 to 73 years. Neuropathological material was collected from several sources in Great Britain and America, and results are reported from the Massachusetts General Hospital, Boston, and the University of Manchester, England. Neurofibrillary tangles (NFTs) accumulated in patients with Down’s syndrome over the age range 35 to 75 years, in the same anatomic locale as individuals with sporadic Alzheimer’s disease. The entorhinal cortex, area CAl/subiculum, and other hippocampal subfields were especially vulnerable. Amyloid deposition is more widespread, accumulating over the years 30 to 50, and then reaching a plateau. Inheritance of the apolipoprotein E (Apo E) e4 genotype predisposed to more than double the amount of amyloid burden and was associated with increased numbers of senile plaques in Down’s syndrome individuals with Alzheimer’s disease. 
COMMENT. In a study at Mount Sinai School of Medicine, NY, the University of Kentucky, and the University of Geneva, Switzerland, quantitative analyses of neuropathologic changes in cerebral cortex of 16 patients (aged 6 to 74 years) with Down’s syndrome and in 10 elderly individuals with Alzheimer’s disease showed a similar time course of neurofibrillary tangle formation. Older patients with Down’s syndrome had more neurofibrillary tangles and senile plaques than patients with Alzheimer’s disease. Amyloid deposition preceeded neurofibrillary tangle formation.