title: Preserved differentiation between physical activity and cognitive performance across young, middle, and older adulthood over 8 years.
abstract: OBJECTIVE
  A critical question in the activity engagement literature is whether physical exercise alters the trajectory of age-related cognitive decline (differential preservation) or is associated with enhanced baseline cognitive ability (preserved differentiation). Further, investigations considering that these relations may differ across young, middle, and older adulthood are rare.
  
  
  METHODS
  We evaluated data from the PATH Through Life Project, where participants aged 20-24, 40-44, and 60-64 years at baseline (n = 6,869) completed physical activity (PA; mild, moderate, and vigorous) and cognitive measurements thrice over 8 years.
  
  
  RESULTS
  Multilevel models accounting for employment status, sex, education, health, and mental and social activity showed that between-person differences in PA participation positively predicted baseline performance on fluid cognitive ability (perceptual speed, short-term memory, working memory, and episodic memory). These effects were similar across age groups, but strongest for the youngest cohort, for whom there was also evidence of covariation between within-person change in PA and cognitive score. PA was not associated with change in cognition over time.
  
  
  CONCLUSIONS
  Results support preserved differentiation, where physically active adults have higher initial cognitive ability, and the advantage is maintained over time. PA appears to be unique in showing differences across young, middle, and older adulthood in predicting cognition.
authors.affiliation: Department of Human Development and Family Studies, Colorado State University, Fort Collins. allison.bielak@colostate.edu.
authors.forename: Allison A M
authors.initials: AA
authors.lastname: Bielak
authors.affiliation: Centre for Research on Ageing, Health and Wellbeing, The Australian National University, Canberra.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Cherbuin
authors.affiliation: Institute of Psychological Sciences, Faculty of Medicine and Health, University of Leeds.
authors.forename: David
authors.initials: D
authors.lastname: Bunce
authors.affiliation: Centre for Research on Ageing, Health and Wellbeing, The Australian National University, Canberra.
authors.forename: Kaarin J
authors.initials: KJ
authors.lastname: Anstey
mesh_terms: D000328:Adult; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013997:Time Factors; D055815:Young Adult
keywords: Activity engagement; Adulthood; Cognitive change; Longitudinal; Physical activity.