title: Intraindividual Cognitive Variability in Middle Age Predicts Cognitive Impairment 8-10 Years Later: Results from the Wisconsin Registry for Alzheimer's Prevention.
abstract: Intraindividual cognitive variability (IICV) has been shown to differentiate between groups with normal cognition, mild cognitive impairment (MCI), and dementia. This study examined whether baseline IICV predicted subsequent mild to moderate cognitive impairment in a cognitively normal baseline sample.
  
  
  
  Participants with 4 waves of cognitive assessment were drawn from the Wisconsin Registry for Alzheimer's Prevention (WRAP; n=684; 53.6(6.6) baseline age; 9.1(1.0) years follow-up; 70% female; 74.6% parental history of Alzheimer's disease). The primary outcome was Wave 4 cognitive status ("cognitively normal" vs. "impaired") determined by consensus conference; "impaired" included early MCI (n=109), clinical MCI (n=11), or dementia (n=1). Primary predictors included two IICV variables, each based on the standard deviation of a set of scores: "6 Factor IICV" and "4 Test IICV". Each IICV variable was tested in a series of logistic regression models to determine whether IICV predicted cognitive status. In exploratory analyses, distribution-based cutoffs incorporating memory, executive function, and IICV patterns were used to create and test an MCI risk variable.
  
  
  
  Results were similar for the IICV variables: higher IICV was associated with greater risk of subsequent impairment after covariate adjustment. After adjusting for memory and executive functioning scores contributing to IICV, IICV was not significant. The MCI risk variable also predicted risk of impairment.
  
  
  
  While IICV in middle-age predicts subsequent impairment, it is a weaker risk indicator than the memory and executive function scores contributing to its calculation. Exploratory analyses suggest potential to incorporate IICV patterns into risk assessment in clinical settings. (JINS, 2016, 22, 1016-1025).
authors.affiliation: 1Wisconsin Alzheimer's Institute,University of Wisconsin School of Medicine and Public Health,Madison,Wisconsin.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Koscik
authors.affiliation: 2Alzheimer's Disease Research Center,University of Wisconsin School of Medicine and Public Health,Madison,Wisconsin.
authors.forename: Sara E
authors.initials: SE
authors.lastname: Berman
authors.affiliation: 1Wisconsin Alzheimer's Institute,University of Wisconsin School of Medicine and Public Health,Madison,Wisconsin.
authors.forename: Lindsay R
authors.initials: LR
authors.lastname: Clark
authors.affiliation: 1Wisconsin Alzheimer's Institute,University of Wisconsin School of Medicine and Public Health,Madison,Wisconsin.
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: Mueller
authors.affiliation: 1Wisconsin Alzheimer's Institute,University of Wisconsin School of Medicine and Public Health,Madison,Wisconsin.
authors.forename: Ozioma C
authors.initials: OC
authors.lastname: Okonkwo
authors.affiliation: 3Geriatric Research Education and Clinical Center,Wm. S. Middleton Veterans Hospital,Madison Wisconsin.
authors.forename: Carey E
authors.initials: CE
authors.lastname: Gleason
authors.affiliation: 1Wisconsin Alzheimer's Institute,University of Wisconsin School of Medicine and Public Health,Madison,Wisconsin.
authors.forename: Bruce P
authors.initials: BP
authors.lastname: Hermann
authors.affiliation: 1Wisconsin Alzheimer's Institute,University of Wisconsin School of Medicine and Public Health,Madison,Wisconsin.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Sager
authors.affiliation: 3Geriatric Research Education and Clinical Center,Wm. S. Middleton Veterans Hospital,Madison Wisconsin.
authors.forename: Sterling C
authors.initials: SC
authors.lastname: Johnson
mesh_terms: D000544:Alzheimer Disease / Q000175:diagnosis*; D060825:Cognitive Dysfunction / Q000175:diagnosis*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis*; D008875:Middle Aged; D011379:Prognosis; D012042:Registries; D014922:Wisconsin
keywords: Alzheimer’s disease; Mild cognitive impairment; Neuropsychological tests; Prodromal period; Psychometrics; Risk screening