During the last decade, senile dementia and the presenile disease that was named after Alois Alzheimer have been considered a single entity called Alzheimer's disease (AD). This same decade has witnessed the development of many diagnostic tools, such as CT, MRI, and SPECT imaging, that have made possible the systematic analysis of symptoms of brain disorders. With the aid of these sophisticated techniques, it is possible to divide the disorder into clinically relevant subgroups, one of which corresponds to the disease first described by Alzheimer. The disease exists in sporadic and familial forms, and in subgroups of these two basic types. Because the heterogeneity of AD is incontestable, it is time to reconsider the current use of the term “Alzheimer's disease.” Because it labels different subgroups whose characteristics are often markedly different, the term “Alzheimer syndrome” appears to be more appr