title: Modeling practice effects in healthy middle-aged participants of the Alzheimer and Families parent cohort.
abstract: BACKGROUND
  Repetitive administration of neuropsychological tests can lead to performance improvement merely due to previous exposure. The magnitude of such practice effects (PEs) may be used as a marker of subtle cognitive impairment because they are diminished in healthy individuals subsequently developing Alzheimer's disease (AD).
  
  
  METHODS
  To explore the relationship between sociodemographic factors, AD family history (FH), andAPOEε4 status, and the magnitude of PE, four subtests of the Wechsler Adult Intelligence Scale-IV were administered twice to 400 middle-aged healthy individuals, most of them first-degree descendants of AD patients.
  
  
  RESULTS
  PEs were observed in all measures. Sociodemographic variables did not show a uniform effect on PE. Baseline score was the strongest predictor of change, being inversely related to PE magnitude. Significant effects of the interaction termAPOEε4∗Age in processing speed and working memory were observed.
  
  
  CONCLUSIONS
  PEs exert a relevant effect in cognitive outcomes at retest and, accordingly, they must be taken into consideration in clinical trials. The magnitude of PE in processing speed and working memory could be of special interest for the development of cognitive markers of preclinical AD.
authors.affiliation: Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Sánchez-Benavides
authors.affiliation: Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain; Universitat Pompeu Fabra, Barcelona, Spain.
authors.forename: Juan D
authors.initials: JD
authors.lastname: Gispert
authors.affiliation: Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain.
authors.forename: Karine
authors.initials: K
authors.lastname: Fauria
authors.affiliation: Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Molinuevo
authors.affiliation: Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain.
authors.forename: Nina
authors.initials: N
authors.lastname: Gramunt
keywords: APOE; Alzheimer's disease; Cognition; Family history; Practice effects; Preclinical