The etiology of Alzheimer's disease: epidemiologic contributions with emphasis on the genetic hypothesis.

This report reviews the contributions of analytic epidemiology to the generation and testing of etiologic hypotheses for clinically diagnosed Alzheimer's disease (AD). Because AD can be diagnosed with certainty only at autopsy, currently available epidemiologic data are often based on a presumed clinical diagnosis. Several case-control studies have shown that cases of either dementia or Down's syndrome in other family members, advanced age of the mother at subject's birth, and head injury are possible risk factors. Many other factors have been investigated but were not found to be consistently associated.