title: Validation of a latent variable representing the dementing process.
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.
authors.affiliation: Department of Psychiatry, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA. royall@uthscsa.edu
authors.forename: Donald R
authors.initials: DR
authors.lastname: Royall
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Palmer
authors.forename: Sid E
authors.initials: SE
authors.lastname: O'Bryant
mesh_terms: D000203:Activities of Daily Living / Q000523:psychology*; D001288:Attention; D003071:Cognition; D003704:Dementia / Q000175:diagnosis* / Q000523:psychology; D056344:Executive Function; D006801:Humans; D007802:Language; D008568:Memory; D008960:Models, Psychological; D009483:Neuropsychological Tests