title: Selective attrition and intraindividual variability in response time moderate cognitive change.
abstract: OBJECTIVE
  Selection of a developmental time metric is useful for understanding causal processes that underlie aging-related cognitive change and for the identification of potential moderators of cognitive decline. Building on research suggesting that time to attrition is a metric sensitive to non-normative influences of aging (e.g., subclinical health conditions), we examined reason for attrition and intraindividual variability (IIV) in reaction time as predictors of cognitive performance.
  
  
  METHODS
  Three hundred and four community dwelling older adults (64-92 years) completed annual assessments in a longitudinal study. IIV was calculated from baseline performance on reaction time tasks. Multilevel models were fit to examine patterns and predictors of cognitive change.
  
  
  RESULTS
  We show that time to attrition was associated with cognitive decline. Greater IIV was associated with declines on executive functioning and episodic memory measures. Attrition due to personal health reasons was also associated with decreased executive functioning compared to that of individuals who remained in the study.
  
  
  CONCLUSIONS
  These findings suggest that time to attrition is a useful metric for representing cognitive change, and reason for attrition and IIV are predictive of non-normative influences that may underlie instances of cognitive loss in older adults.
authors.affiliation: a Department of Psychology , York University , Toronto , ON , Canada.
authors.forename: Christie
authors.initials: C
authors.lastname: Yao
authors.affiliation: b College of Public Health and Human Sciences, Oregon State University , Corvallis , OR , USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Stawski
authors.affiliation: c Department of Psychology , University of Victoria , Victoria , BC , Canada.
authors.forename: David F
authors.initials: DF
authors.lastname: Hultsch
authors.affiliation: c Department of Psychology , University of Victoria , Victoria , BC , Canada.
authors.forename: Stuart W S
authors.initials: SW
authors.lastname: MacDonald
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology; D018450:Disease Progression; D015340:Epidemiologic Research Design; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011930:Reaction Time / Q000502:physiology*; D012107:Research Design / Q000592:standards*
keywords: Intraindividual variability; aging; attrition; cognition; longitudinal change