δ scores predict mild cognitive impairment and Alzheimer's disease conversions from nondemented states

INTRODUCTION: We tested the latent variable “δ” (for “dementia”)'s ability to predict conversion to “mild cognitive impairment” (MCI) and Alzheimer's disease (AD). METHODS: An ethnicity equivalent d homolog (“dEQ”) was constructed in n = 1113 Mexican- American (MA) and n = 1958 non-Hispanic white (NHW) participants in the Texas Alzheimer's Research and Care Consortium. “Normal Controls” (NC) (n = 1276) and MCI cases (n = 611) were followed annually for up to 6 years [m = 4.7(0.6)]. RESULTS: 22.0% (n = 281) of NC converted to “MCI” or “AD”. 17.3%( n = 106) of MCI converted to “AD.” Independently of covariates, each quintile increase in the dEQ scores of NC increased the odds of conversion by 52%. Each quintile increase in the dEQ scores of MCI cases increased the odds of conversion to AD almost three-fold. DISCUSSION: Baseline δ scores predict MCI and AD conversions from nondemented states in MA and NHW.