Aphasia, family history, and the longitudinal course of senile dementia of the Alzheimer type.

Aphasia, was present in a majority of subjects in a longitudinal study of 43 subjects with senile dementia of the Alzheimer type. Aphasic subjects had a more rapidly progressive course but a lower prevalence of familial cases than the study group, other study groups, or the nonaphasic subjects. Conversely, the lack of aphasia was associated with a higher prevalence of familial cases and a slower rate of progression. It is concluded that senile dementia of the Alzheimer type is a heterogeneous disorder in which the presence of aphasia early in the course signifies a nonfamilial, rapidly progressive variety of illness.