The Use of Short Versions of the Japanese WAIS-III to Aid in Differentiation Between Alzheimer's Disease and Dementia with Lewy Bodies

Abstract

Objective: We examined the cognitive characteristics of patients with Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) using the Wechsler Adult Intelligent Scale-Third Edition (WAIS-III). In addition, the utility of short versions of WAIS-III for estimating IQ scores and index scores were examined. Methods: The subjects were 83 patients with probable AD, 33 patients with probable DLB, and 83 cognitively normal individuals. Results: Patients with DLB showed significantly lower scores in Performance IQ and Processing Speed compared with those with AD. The short versions of WAIS-III with Information, Similarities, Arithmetic, Digit Span, Picture Completion, Digit Symbol-Coding, and Block Design demonstrated relatively small amount of error, high correlations, and reliabilities with the full version. Conclusions: The results indicated that Performance IQ and Processing Speed in WAIS-III can be an indicator for differentiating AD and DLB in WAIS-III, and a short version obtained by the Similarities, Information, Picture Completion, Block Design, Arithmetic, Digit Span, and Digit-Symbol Coding yields high accuracy and can be used to estimate full-scale IQ scores on the WAIS-III.