Association between Dementia Rating Scale performance and neurocognitive domains in Alzheimer's disease

The Dementia Rating Scale (DRS; Mattis, 1976, 1988) is commonly used in the assessment of dementia, although little is known about the relationship of performance on this test to specific cognitive deficits in Alzheimer's disease (AD). Additionally, cognitive profiles have not been investigated across different levels of dementia as determined by the DRS. A sample of 133 individuals diagnosed with possible or probable AD was administered the DRS as part of a comprehensive neuropsychological evaluation. Composite scores for the cognitive domains of attention, executive functioning, visuospatial skills, language abilities, immediate recall, and delayed memory were derived by averaging demographically corrected T scores of key measures. Individual domain scores were also averaged to develop a global index score. Pearson correlations between composite and total DRS scores were highly significant (p<.001) for all domains and the global index score, with the exception of delayed memory, which showed a floor effect. When the sample was divided into mild and moderate-to-severe groups to examine the effects of disease severity on the relationship between the DRS and standard neurocognitive domain scores, the resulting mean neuropsychological profile scores were significantly different while maintaining a parallel pattern of impairment across domains. Results demonstrate the relationship between the DRS and standard cognitive domain functions, which appears to underscore the validity and robustness of the DRS in characterizing patterns of cognitive impairment across the AD spectrum.