DEVELOPMENT OF APHASIA, APRAXIA, AND AGNOSIA AND DECLINE IN ALZHEIMERS-DISEASE

Objective: The purpose of this study was to compare the stage and the subtype models of disease progression in Alzheimer's disease. The auth ors address the issue of whether the overall rate of clinical decline is different in Alzheimer's disease patients with and without early de velopment of aphasia, apraxia, or agnosia. Method: The study was a cas e series study. Two separate cohorts of Alzheimer's disease patients w ere used, one from an ongoing single center study at Stanford Universi ty (N=57) and the other from a multicenter project across the state of California (N=70). Patients were assessed every 6 months in the Stanf ord study and yearly in the state study. All patients were assessed at least three times. The outcome measure was the average rate of declin e on the Mini-Mental State examination. Results: The average rates of decline on the Mini-Mental State were computed for each subject. Subje cts were then divided among groups according to whether and when they exhibited aphasia, agnosia, or apraxia. The effects of the presence of aphasia, agnosia, or apraxia were assessed by comparing the average r ates of decline on the Mini-Mental State. Conclusions: Alzheimer's dis ease patients who developed aphasia or apraxia declined more rapidly t han those patients who did not develop either sign. These results were not attributable to differences in Mini-Mental State scores at entry into the study. The results suggest the presence of subtypes of Alzhei mer's disease in which accelerated decline is associated with the earl y appearance of certain neurological signs.