title: Relation of plasma homocysteine to plasma amyloid beta levels.
abstract: BACKGROUND
  Elevated plasma homocysteine and amyloid beta (Abeta) have been associated with Alzheimer's disease (AD). We investigated the cross-sectional association between these biomarkers.
  
  
  METHODS
  We used linear regression to relate plasma homocysteine and Abeta adjusting for age, gender, creatinine, APOE-epsilon4, and ethnic group in 327 persons aged 78 +/- 6.6 years.
  
  
  RESULTS
  Plasma homocysteine correlated with age, serum creatinine, plasma Abeta40 and Abeta42, and was inversely correlated with serum vitamin B12, and folate. Abeta42, but not Abeta40, was related to later development of dementia. Homocysteine was related to higher Abeta40 levels (coefficient = 2.0; P < 0.0001) and this association was attenuated after adjustment for creatinine (coefficient = 1.0; P < 0.0001). The crude association between homocysteine and Abeta42 was weaker (coefficient = 0.5; P = 0.01) and became non-significant after adjustment for creatinine (coefficient = 0.4; P = 0.06). These associations were unrelated to ethnicity, the presence of APOE-epsilon4 or dementia. Analyses by quartiles of homocysteine showed that these association were driven primarily by the fourth quartile.
  
  
  CONCLUSIONS
  Plasma homocysteine is directly related to Abeta40. The association with Abeta42 is not significant. These results seem to indicate that homocysteine is related to aging but not specifically to AD.
authors.affiliation: Taub Institute for Research of Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA.
authors.forename: José A
authors.initials: JA
authors.lastname: Luchsinger
authors.forename: Ming-Xin
authors.initials: MX
authors.lastname: Tang
authors.forename: Joshua
authors.initials: J
authors.lastname: Miller
authors.forename: Ralph
authors.initials: R
authors.lastname: Green
authors.forename: Pankash D
authors.initials: PD
authors.lastname: Mehta
authors.forename: Richard
authors.initials: R
authors.lastname: Mayeux
mesh_terms: D000368:Aged; D016229:Amyloid beta-Peptides / Q000097:blood*; D000704:Analysis of Variance; D053327:Apolipoprotein E4 / Q000097:blood; D015415:Biomarkers; D003072:Cognition Disorders / Q000453:epidemiology; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D003704:Dementia / Q000453:epidemiology; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D016014:Linear Models; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data; D009519:New York City / Q000453:epidemiology; D010446:Peptide Fragments / Q000097:blood
chemical_list: D016229:Amyloid beta-Peptides; D053327:Apolipoprotein E4; D015415:Biomarkers; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); D006710:Homocysteine; D003404:Creatinine