title: Effects of demographic and health variables on Rasch scaled cognitive scores.
abstract: OBJECTIVE
  To determine whether demographic and health variables interact to predict cognitive scores in Asset and Health Dynamics of the Oldest-Old (AHEAD), a representative survey of older Americans, as a test of the developmental discontinuity hypothesis.
  
  
  METHODS
  Rasch modeling procedures were used to rescale cognitive measures into interval scores, equating scales across measures, making it possible to compare predictor effects directly. Rasch scaling also reduces the likelihood of obtaining spurious interactions. Tasks included combined immediate and delayed recall, the Telephone Interview for Cognitive Status (TICS), Series 7, and an overall cognitive score.
  
  
  RESULTS
  Demographic variables most strongly predicted performance on all scores, with health variables having smaller effects. Age interacted with both demographic and health variables, but patterns of effects varied.
  
  
  CONCLUSIONS
  Demographic variables have strong effects on cognition. The developmental discontinuity hypothesis that health variables have stronger effects than demographic ones on cognition in older adults was not supported.
authors.affiliation: Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA. zelinski@usc.edu
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Zelinski
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gilewski
mesh_terms: D000367:Age Factors; D000368:Aged; D000375:Aging; D003071:Cognition; D003710:Demography; D004522:Educational Status; D005260:Female; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D008297:Male; D011594:Psychometrics; D012737:Sex Factors; D012959:Socioeconomic Factors; D014481:United States