title: Plasma beta amyloid and the risk of Alzheimer disease and dementia in elderly men: a prospective, population-based cohort study.
abstract: BACKGROUND
  Beta amyloid (Abeta) protein accumulates in the brains of individuals with Alzheimer disease (AD) and is detectable in cerebrospinal fluid and plasma.
  
  
  OBJECTIVE
  To examine plasma levels of Abeta peptides Abeta(40) and Abeta(42) as predictors of incident AD and other types of dementia.
  
  
  METHODS
  Prospective, population-based cohort study.
  
  
  METHODS
  The Uppsala Longitudinal Study of Adult Men.
  
  
  METHODS
  Plasma Abeta(40) and Abeta(42) levels were analyzed as predictors of incident AD in 1045 men at age 70 years and 680 men at age 77 years using Cox proportional hazards analyses. Alzheimer disease and other types of dementia were diagnosed by standardized screening, clinical evaluation, and medical record review.
  
  
  METHODS
  Hazard ratios of AD (primary outcome) and vascular dementia or other dementia (secondary outcomes) according to baseline levels of plasma Abeta(40) and Abeta(42).
  
  
  RESULTS
  From the age of 77 years at baseline, 46 individuals developed AD at follow-up (median, 5.3 years). A low plasma Abeta(40) level at age 77 years was associated with higher incidence of AD. The multivariate-adjusted hazard ratio was 4.87 (95% confidence interval, 1.63-14.6) for the lowest Abeta(40) tertile compared with the highest tertile. On follow-up from age 70 years at baseline (median, 11.2 years), 82 individuals developed AD. Plasma Abeta(40) and Abeta(42) levels measured at age 70 years were not significantly associated with incident AD.
  
  
  CONCLUSIONS
  Low plasma Abeta(40) levels predicted incident AD in elderly men independently of potential confounders. Plasma Abeta(42) levels were not significantly associated with AD incidence. The clinical value of Abeta measurement in plasma remains to be established in future studies.
authors.affiliation: Uppsala University, Department of Public Health and Geriatrics, Uppsala Science Park, Dag Hammarskölds väg 14B, Uppsala, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Sundelöf
authors.forename: Vilmantas
authors.initials: V
authors.lastname: Giedraitis
authors.forename: Michael C
authors.initials: MC
authors.lastname: Irizarry
authors.forename: Johan
authors.initials: J
authors.lastname: Sundström
authors.forename: Erik
authors.initials: E
authors.lastname: Ingelsson
authors.forename: Elina
authors.initials: E
authors.lastname: Rönnemaa
authors.forename: Johan
authors.initials: J
authors.lastname: Arnlöv
authors.forename: Malin Degerman
authors.initials: MD
authors.lastname: Gunnarsson
authors.forename: Bradley T
authors.initials: BT
authors.lastname: Hyman
authors.forename: Hans
authors.initials: H
authors.lastname: Basun
authors.forename: Martin
authors.initials: M
authors.lastname: Ingelsson
authors.forename: Lars
authors.initials: L
authors.lastname: Lannfelt
authors.forename: Lena
authors.initials: L
authors.lastname: Kilander
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000097:blood* / Q000453:epidemiology*; D016229:Amyloid beta-Peptides / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003704:Dementia / Q000097:blood / Q000453:epidemiology; D015140:Dementia, Vascular / Q000097:blood / Q000453:epidemiology; D018572:Disease-Free Survival; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers