title: Better Cognition in New Birth Cohorts of 70 Year Olds, But Greater Decline Thereafter.
abstract: OBJECTIVE
  To evaluate birth cohort differences in level of cognition and rate of change in old age.
  
  
  METHODS
  Data were drawn from three population-based Swedish samples including age-homogenous cohorts born 1901/02, 1906/07, and 1930, and measured on the same cognitive tests at ages 70, 75, and 79 as part of the Gerontological and Geriatric Populations Studies in Gothenburg (H70). We fitted growth curve models to the data using a Bayesian framework and derived estimates and inferences from the marginal posterior distributions.
  
  
  RESULTS
  We found moderate to large birth cohort effects in level of performance on all cognitive outcomes. Later born cohorts, however, showed steeper linear rate of decline on reasoning, spatial ability, and perceptual- and motor-speed, but not on picture recognition memory and verbal ability.
  
  
  CONCLUSIONS
  These findings provide strong evidence for substantial birth cohort effects in cognition in older ages and emphasize the importance of life long environmental factors in shaping cognitive aging trajectories. Inferences from cognitive testing, and standardization of test scores, in elderly populations must take into account the substantial birth cohort differences.
authors.affiliation: Department of Psychology, University of Gothenburg, Sweden. valgeir.thorvaldsson@psy.gu.se.
authors.forename: Valgeir
authors.initials: V
authors.lastname: Thorvaldsson
authors.affiliation: Department of Psychology, University of Gothenburg, Sweden.|School of Health and Welfare, Halmstad University, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Karlsson
authors.affiliation: Department of Psychology, University of Gothenburg, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Skoog
authors.affiliation: Department of Psychiatry and Neurochemistry, Institute of Neuroscience of Physiology, Sahlgrenska Academy at the University of Gothenburg, Sweden.
authors.forename: Ingmar
authors.initials: I
authors.lastname: Skoog
authors.affiliation: Department of Psychology, University of Gothenburg, Sweden.
authors.forename: Boo
authors.initials: B
authors.lastname: Johansson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000175:diagnosis* / Q000523:psychology*; D000066492:Cognitive Aging / Q000523:psychology*; D015331:Cohort Studies; D018450:Disease Progression; D006801:Humans; D016014:Linear Models; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011594:Psychometrics; D012931:Social Environment; D013548:Sweden
keywords: Aging; Cognition; Cognitive change; Cohort differences; Cohort effects