Objective: Royall and colleagues identified a latent dementia phenotype, “d”, reflecting the “cognitive correlates of functional status.” We sought to cross-validate and extend these findings in a large clinical case series of adults with and without dementia. Method: A confirmatory factor analysis (CFA) model for d was fit to National Alzheimer’s Coordinating Center data (n = 26,068). Factor scores derived from d were compared with the Clinical Dementia Rating Sum of Boxes (CDR-SB) and to clinically diagnosed dementia. A longitudinal parallel-process growth model compared changes in d with changes in CDR-SB over 6 annual evaluations. Results: The CFA model fit well; CFI = 0.971, RMSEA = 0.070. Factor scores derived from d discriminated between demented and nondemented participants with an area under the curve of .96. The growth model also fit well, CFI = 0.969, RMSEA = 0.032. Conclusions: The d construct represents a novel approach to measuring dementia-related changes and has potential to improve cognitive assessment of neurodegenerative diseases.
