A comparison of selected subtest scores on the Wechsler Adult Intelligence Scale-Revised-Neuropsychological Instrument (WAIS-R-NI) and the Dementia Rating Scale (DRS) in classifying dementia.

Abstract

The purpose of this study was to investigate the relationship between the Verbal subtests of the Wechsler Adult Intelligence Scale-RevisedNeuropsychological Instrument (WAIS-R-NI) and the Initiation/Perseveration subtest of the Dementia Rating Scale (DRS) in classifying dementia. Additionally, DRS raw scores and WAIS-R-NI scaled score ranges were compared independently to Verbal 10 scores to determine a degree of relationship. The sample consisted of 30 senior citizens (females and males) ranging in age from 65 to 79. Both the WAIS-R-NI and DRS were administered to each participant. Scores for both tests were recorded for each participant. For the clinical sample, demographic information was obtained from medical records through the assistance of nursing home staff. This information included gender, date of birth, date of medical diagnosis for dementia and medications affecting alertness. Pearson product-moment correlation coefficients were calculated to determine the relationships between the DRS raw scores, WAIS-R-NI Verbal subtest scaled score ranges and Verbal 10 scores. A 2 X 2 chi square test of independence was calculated separately for the WAIS-R-NI and DRS subtests. This was done to determine if the expected test scores, categorized as medical diagnoses (dementia or non-dementia). corresponded with the observed scores in classifying dementia from non-dementia. Participants were categorized by two levels, medically diagnosed dementia and non-dementia. Correlations indicated no significant relationships between the produced scores of DRS and Verbal 10 , or WAIS-R-NI and Verbal 10. Participants in the non-dementia group had higher Verbal lOs than those medically diagnosed with dementia. Two chi square analyses were calculated separately for the DRS and the WAIS-R-NI. The results indicated that the DRS Initiation/Perseveration subtest identified correctly 100% of the dementia and non-dementia participants. The WAIS-R-NI scaled score range correctly identified 13% of the dementia participants, and 100% of those with non-dementia. Results suggest that the DRS is effective as a discriminant function between dementia and nondementia cases. The WAIS-R-NI scaled score range appears to be more favorable for identifying non-dementia over dementia participants but may not be considered a valid discriminant. These results indicate that the DRS Initiation/Perseveration subtest does correctly identify those individuals diagnosed with dementia and may be effective in detecting cognitive decline in those suspected of having brain organicity. However, its use may only be suggested for determining if a more comprehensive examination is warranted. Caution should be used when using the WAIS-R-NI scaled score range to differentiate dementia from non-dementia.