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Updated: May 23, 2026

Lexical Decision Task for Studying Written Word Recognition in Adults with and without Dementia or Mild Cognitive Impairment
Published on: June 25, 2019
Validation of a latent variable representing the dementing process
Donald R Royall1, Raymond F Palmer, Sid E O'Bryant
1Department of Psychiatry, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA. royall@uthscsa.edu
Abstract:
The cognitive correlates of functional status are essential to dementia case-finding. Nevertheless, cognitive performance is a generally weak predictor of functional outcomes. We have employed structural equation models to explicitly distinguish functional status, and therefore "dementia-relevant" variance in cognitive task performance (i.e., δ) from the variance that is unrelated to a dementing process (i.e., g'). Together, g' + δ encompass Spearman's g. Although δ represents only a small fraction of the total variance in cognitive task performance, it is more strongly associated with dementia status than is g'. In this study, we validate δ in a well characterized Alzheimer's disease cohort, the Texas Alzheimer's Research and Care Consortium. Our approach results in "error free" continuous variables. This suggests that δ can serve as a dementia specific endophenotype. As a result, future studies may be able to associate δ with inflammatory and genetic biomarkers.
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