NEUROPSYCHOLOGICAL SUBGROUPS OF PATIENTS WITH ALZHEIMERS-DISEASE

Neuropsychological data from 134 patients diagnosed with probable Alzh eimer's disease (AD) were studied retrospectively to investigate wheth er subgroups of patients with qualitatively distinct profiles could be identified. Three empirical classification approaches were undertaken in this regard: Q-type factor analysis, hierarchical agglomerative cl uster analysis, and iterative partitioning. Three subgroups were consi stently identified across the clustering methods. Subgroup 1, the larg est of the groups, was marked by moderate to severe anemia and constru ctional dyspraxia. Individuals in subgroup 2 displayed relatively spar ed visual-perceptual/constructional functioning but severe anemia. Mem bers of subgroup 3 exhibited intact naming and nonverbal reasoning and moderate difficulty in copying overlapping figures. The three subgrou ps did not differ with respect to age, age at disease onset, duration of illness, educational level, or Hamilton depression rating. Detailed description of the data analyses are provided as a tutorial outlining subtyping methodology. Results are discussed in terms of the subgroup and the stage model approaches to the conceptualization of AD.