摘要: • Relatives of 125 probands, who had dementia the Alzheimer type as proved by autopsy, were subjects a genetic investigation. The relatives exhibited an excess dementing illness consistent with transmission. Risk to decreased sharply severity proband's decreased. Also, when compared control group and general population, excesses Down's syndrome, lymphoma, immune diatheses. These associated conditions also more likely be present proband severe illness. Mortality at all ages was increased among relatives.