title: Plasma Abeta42 and Abeta40 as markers of cognitive change in follow-up: a prospective, longitudinal, population-based cohort study.
abstract: BACKGROUND
  Single measurements of plasma Aβ are not useful in the diagnostics of Alzheimer's disease (AD). However, changes in plasma Aβ levels during repeated testing may be helpful in the prediction and evaluation of progression of the incipient AD or mild cognitive impairment.
  
  
  OBJECTIVE
  To examine the relation of baseline and serial plasma Aβ levels to cognitive change in follow-up.
  
  
  METHODS
  269 subjects (52 cognitively impaired and 217 controls) from a population-based cohort were clinically followed up from 3 to 6 years. Serial plasma samples were available from 70 subjects who were followed up for 3 years and 43 subjects followed for 6 years. The plasma Aβ levels were measured using ELISA.
  
  
  RESULTS
  Subjects who declined cognitively during the follow-up had lower levels of plasma Aβ42 at the baseline. Plasma Aβ42 and the Aβ42/Aβ40 ratio decreased (-2.4 pg/ml for Aβ42 in 6 years) in those who declined in follow-up, whereas Aβ42 and the Aβ42/Aβ40 ratio increased in the subjects who remained cognitively stable or improved in follow-up. Subjects using acetylsalicylic acid, dipyridamole, antidiabetic or anticoagulant drugs as well as subjects with coronary heart disease had higher levels of Aβ40.
  
  
  CONCLUSIONS
  Low or decreasing plasma Aβ42 during the follow-up is associated with cognitive decline. Serial measurement of plasma Aβ42 may be useful in the detection of the subjects who are at risk for cognitive decline.
authors.affiliation: Department of Neurology, Kuopio University Hospital, University of Eastern Finland, Kuopio, Finland.
authors.forename: T T
authors.initials: TT
authors.lastname: Seppälä
authors.forename: S-K
authors.initials: SK
authors.lastname: Herukka
authors.forename: T
authors.initials: T
authors.lastname: Hänninen
authors.forename: S
authors.initials: S
authors.lastname: Tervo
authors.forename: M
authors.initials: M
authors.lastname: Hallikainen
authors.forename: H
authors.initials: H
authors.lastname: Soininen
authors.forename: T
authors.initials: T
authors.lastname: Pirttilä
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis*; D016229:Amyloid beta-Peptides / Q000097:blood*; D015415:Biomarkers / Q000097:blood*; D003072:Cognition Disorders / Q000097:blood / Q000175:diagnosis*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood*
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers; D010446:Peptide Fragments