In 1907, Aloysius "Alois" Alzheimer presented a rare case of dementia in a 51-year-old woman. This "presenile dementia" (younger than 60) was thought distinct enough from "senile dementia" (older than 65) to warrant a new name, thus it became known as, "Alzheimer's disease" (AD).

In the 1970s, however, some researchers argued that because of their similar symptoms and diagnostic hallmarks, "Alzheimer disease and senile dementia should be considered a single disease."1 This would mean that Alzheimer was wrong. Since then, AD research has been directed at finding a pathogenic cause, be it genetic, metabolic, toxic, or some other causative factor. But after 30 years, while the cause for presenile dementia, or early-onset familial AD, has been essentially found in the form of three mutant genes, the cause for senile dementia, or late-onset sporadic AD, remains unknown.2 Perhaps Alzheimer was right,...