ABSTRACT
“Alzheimer’s disease” is so universally recognized as the major dementing disorder of aging that the term has become part of everyday speech. This recognition reflects the reality of late 20th century demography: Alzheimer’s disease epitomizes the age-dependent disorders of late life with the prevalence doubling every 5 years of age, at least between ages 65 and 85. For research to progress, the question of the identity of Alzheimer’s disease as a presenile disorder and senile dementia had to be established. The unique molecule at the core of the neuritic plaque in Alzheimer’s disease has been shown to be a small protein or peptide, 38 to 42 amino acids long, which has been termed A/ß-amyloid. The second fibrous protein characteristic of Alzheimer’s disease is tau, the protein that constitutes the paired helical filament. Among the neurodegenerative diseases, ß-amyloid plaques only occur in Alzheimer’s disease and Down’s syndrome.
