title: Prospective study of risk factors for Alzheimer's disease: results at 7.5 years.
abstract: OBJECTIVE
  The primary goal of this study was to evaluate increased platelet membrane fluidity as a putative risk factor for Alzheimer's disease and its relationship to the APOE epsilon4 genotype.
  
  
  METHODS
  This report describes the results of a prospective, longitudinal study of 330 initially asymptomatic, first-degree relatives of probands with Alzheimer's disease.
  
  
  RESULTS
  Nine incident cases of Alzheimer's disease were detected during the first 2,220 subject-years of the follow-up period. Age, increased platelet membrane fluidity, and the APOE epsilon4 allele made significant independent contributions to the risk of developing Alzheimer's disease, while sex and years of education did not. Increased platelet membrane fluidity was associated with incident Alzheimer's disease cases between the ages of 64 and 71, while the epsilon4 allele was associated with incident Alzheimer's disease cases from age 64 until at least age 80.
  
  
  CONCLUSIONS
  These results indicate that increased platelet membrane fluidity is not produced by the APOE epsilon4 allele. Instead, increased platelet membrane fluidity and the epsilon4 allele appear to make significant independent contributions to the risk of developing Alzheimer's disease among the first-degree relatives of patients with this disorder. Moreover, the age ranges over which these risk factors operate appear to be different.
authors.affiliation: Department of Psychiatry, University of Pittsburgh School of Medicine, PA, USA.
authors.forename: G S
authors.initials: GS
authors.lastname: Zubenko
authors.forename: E
authors.initials: E
authors.lastname: Winwood
authors.forename: B
authors.initials: B
authors.lastname: Jacobs
authors.forename: I
authors.initials: I
authors.lastname: Teply
authors.forename: J S
authors.initials: JS
authors.lastname: Stiffler
authors.forename: H B
authors.initials: HB
authors.lastname: Hughes
authors.forename: F J
authors.initials: FJ
authors.lastname: Huff
authors.forename: T
authors.initials: T
authors.lastname: Sunderland
authors.forename: A J
authors.initials: AJ
authors.lastname: Martinez
mesh_terms: D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000544:Alzheimer Disease / Q000097:blood / Q000453:epidemiology* / Q000235:genetics; D001057:Apolipoproteins E / Q000097:blood / Q000235:genetics*; D001792:Blood Platelets / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008560:Membrane Fluidity / Q000235:genetics / Q000502:physiology; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D001057:Apolipoproteins E