title: Homocysteine, B vitamins, and the incidence of dementia and cognitive impairment: results from the Sacramento Area Latino Study on Aging.
abstract: BACKGROUND
  High concentrations of homocysteine have been linked to a greater risk of Alzheimer disease, dementia, and cognitive decline.
  
  
  OBJECTIVE
  We evaluated the association between homocysteine and 4.5-y combined incidences of dementia and cognitive impairment without dementia (CIND) in a cohort of 1779 Mexican Americans aged 60-101 y.
  
  
  METHODS
  Homocysteine, red blood cell (RBC) folate, and plasma vitamin B-12 were measured at baseline. New cases of dementia or CIND were ascertained by neuropsychological and clinical examinations and expert adjudication. We used proportional hazards models to estimate the risk of homocysteine-associated dementia or CIND and the influence of RBC folate and plasma vitamin B-12 on that association.
  
  
  RESULTS
  High homocysteine concentrations were associated with a greater risk of dementia or CIND: hazard ratio (HR): 2.39; 95% CI: 1.11, 5.16. Plasma vitamin B-12 modified the association between homocysteine and the outcome. The rates of dementia or CIND associated with homocysteine for those in the lowest and highest tertiles of vitamin B-12, respectively, were significantly higher (HR: 1.61, P = 0.04) and lower (HR: 0.94, P = 0.015) than the risk for those in the middle tertile.
  
  
  CONCLUSIONS
  Homocysteine is an independent risk factor for both dementia and CIND. Higher plasma vitamin B-12 may reduce the risk of homocysteine-associated dementia or CIND.
authors.affiliation: Epidemiology Program, School of Public Health, University of Michigan, Ann Arbor, MI 48104, USA. mnhaan@umich.edu
authors.forename: Mary N
authors.initials: MN
authors.lastname: Haan
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Miller
authors.forename: Allison E
authors.initials: AE
authors.lastname: Aiello
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Whitmer
authors.forename: William J
authors.initials: WJ
authors.lastname: Jagust
authors.forename: Dan M
authors.initials: DM
authors.lastname: Mungas
authors.forename: Lindsay H
authors.initials: LH
authors.lastname: Allen
authors.forename: Ralph
authors.initials: R
authors.lastname: Green
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D002140:California / Q000453:epidemiology; D003072:Cognition Disorders / Q000453:epidemiology*; D003704:Dementia / Q000453:epidemiology*; D004198:Disease Susceptibility; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006306:Health Surveys; D006630:Hispanic or Latino / Q000706:statistics & numerical data*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D020521:Stroke; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12