Intellectual loss in Alzheimer's dementia and WAIS-R intrasubtest scatter

Patterns of intrasubtest scatter in the WAIS-R protocols of patients (n = 32) with Alzheimer's disease were compared to those of normal elderly controls (n = 32). The Alzheimer's patients showed more randomly dispersed item failures on some subtests, but normal controls showed more intrasubtest variability on other measures. Rates of correct diagnostic classification based on scatter measures were only slightly better than chance despite the presence of prominent anomia, memory impairment, construction apraxia, and significant decline from premorbid intellectual level in demented patients. In contrast, demographically based estimates of intellectual loss produced accurate diagnostic classification in 81% of the cases. The incremental validity of qualitative scatter analysis in the evaluation of suspected Alzheimer's disease appears to be minimal.