Neuropsychological and computerized axial tomography volume characteristics of empirically derived dementia subgroups.
Neuropsychological assessment data from 138 Alzheimer's disease patients were cluster-analyzed to yield five separate subgroups. These clusters are best described as follows. Cluster I is a low-functioning subgroup characterized by severe generalized deficits (N = 25), cluster II is a subgroup characterized by a higher level of visual-spatial skills relative to the other groups (N = 39), cluster III (N = 21) and cluster IV (N = 42) are virtually indistinguishable in terms of verbal ability and memory, but do differ with regard to visual-spatial skills, and cluster V is a subgroup which presented with relatively better preserved verbal abilities (N = 11). Despite their different neuropsychological profiles, the subgroups did not differ significantly with regard to those complaints that were noted early in the course of the disease process. However, they were found to differ significantly with regard to the patients' educational backgrounds, the distribution of males and females, and the age of the patients at the time of onset of the disease. Analysis of the degree and lateralization of cortical atrophy using volumetric techniques suggested little relationship with neuropsychological examination results. Ventricular volume differences among the five subgroups were not found to be statistically significant after the effect of age had been partialled out. Results are discussed in relation to the multiple factors relating to brain structure and cognition in Alzheimer's disease.