title: Cognitive variability-A marker for incident MCI and AD: An analysis for the Alzheimer's Disease Neuroimaging Initiative.
abstract: BACKGROUND
  The potential of intra-individual cognitive variability (IICV) to predict incident mild cognitive impairment (MCI) or Alzheimer's disease (AD) was examined and compared to well-established neuroimaging and genetic predictors.
  
  
  METHODS
  IICV was estimated using four neuropsychological measures for n = 1324 Alzheimer's Disease Neuroimaging Initiative (ADNI) participants who were cognitively healthy or diagnosed with MCI at baseline. IICV was used to predict time to incident MCI or AD, and compared to hippocampal volume loss and APOE ε4 status via survival analysis.
  
  
  RESULTS
  In survival analyses, controlling for age, education, baseline diagonosis, and APOE ε4 status, likelihood ratio tests indicate that IICV is associated with time to cognitive status change in the full sample (P < .0001), and when the sample was restricted to individuals with MCI at baseline (P < .0001).
  
  
  CONCLUSIONS
  These findings suggest IICV may be a low-cost, noninvasive alternative to traditional AD biomarkers.
authors.affiliation: Department of Human Services, School of Education and Human Services, Wright State University, Dayton, OH, USA.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Anderson
authors.affiliation: Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA; Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Wahoske
authors.affiliation: Department of Human Services, School of Education and Human Services, Wright State University, Dayton, OH, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Huber
authors.affiliation: Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI, USA.
authors.forename: Derek
authors.initials: D
authors.lastname: Norton
authors.affiliation: Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI, USA.
authors.forename: Zhanhai
authors.initials: Z
authors.lastname: Li
authors.affiliation: Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Koscik
authors.affiliation: Department of Rehabilitation Psychology and Special Education, School of Education, University of Wisconsin, Madison, WI, USA.
authors.forename: Emre
authors.initials: E
authors.lastname: Umucu
authors.affiliation: Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA; Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA; Geriatric Research, Education and Clinical Center, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.
authors.forename: Sterling C
authors.initials: SC
authors.lastname: Johnson
authors.affiliation: Department of Neurology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
authors.forename: Jana
authors.initials: J
authors.lastname: Jones
authors.affiliation: Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA; Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Geriatric Research, Education and Clinical Center, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Asthana
authors.affiliation: Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA; Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Geriatric Research, Education and Clinical Center, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.
authors.forename: Carey E
authors.initials: CE
authors.lastname: Gleason
keywords: ADNI; Alzheimer's disease; Alzheimer's disease neuroimaging initiative; Biomarker; Cognitive biomarker; Cognitive variability; MCI; Mild cognitive impairment