title: Homocysteine, vitamin B-12, and folic acid and the risk of cognitive decline in old age: the Leiden 85-Plus study.
abstract: BACKGROUND
  High concentrations of homocysteine and low concentrations of vitamin B-12 and folic acid are frequently observed in subjects with dementia.
  
  
  OBJECTIVE
  We assessed whether serum concentrations of homocysteine, vitamin B-12, or folic acid predict cognitive decline in old age.
  
  
  METHODS
  This was a prospective, population-based, longitudinal study of 599 subjects (Leiden 85-Plus Study, Netherlands). The subjects were administered a battery of cognitive tests (including the Mini Mental State Examination, the Stroop test, a letter digit coding test, and a word recall test) at 85 y of age and yearly thereafter until 89 y of age. Serum concentrations of homocysteine, vitamin B-12, and folic acid were measured at 85 and 89 y of age. Cross-sectional associations between serum concentrations and cognition were assessed at 85 and 89 y of age. The association between baseline serum concentrations and subsequent longitudinal cognitive decline was assessed with the use of mixed linear models.
  
  
  RESULTS
  In the cross-sectional analyses, serum concentrations of homocysteine and folic acid were significantly associated with cognitive performance, but serum concentrations of vitamin B-12 were not. In the longitudinal analyses, there were no significant associations of serum concentrations of homocysteine, vitamin B-12, or folic acid with rate of cognitive decline.
  
  
  CONCLUSIONS
  Elevated serum concentrations of homocysteine and reduced folic acid are associated with cognitive impairment in elderly persons but do not predict an increased rate of cognitive decline. The association of high serum concentrations of homocysteine and low folic acid with cognitive impairment in old age is likely to be a consequence of disease and not a contributory cause.
authors.affiliation: Departments of Gerontology and Geriatrics and Clinical Chemistry, Leiden University Medical Center, Leiden, Netherlands.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Mooijaart
authors.forename: Jacobijn
authors.initials: J
authors.lastname: Gussekloo
authors.forename: Marijke
authors.initials: M
authors.lastname: Frölich
authors.forename: Jelle
authors.initials: J
authors.lastname: Jolles
authors.forename: David J
authors.initials: DJ
authors.lastname: Stott
authors.forename: Rudi G J
authors.initials: RG
authors.lastname: Westendorp
authors.forename: Anton J M
authors.initials: AJ
authors.lastname: de Craen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood* / Q000502:physiology / Q000523:psychology*; D003071:Cognition / Q000502:physiology; D003430:Cross-Sectional Studies; D003704:Dementia / Q000097:blood* / Q000453:epidemiology; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D011446:Prospective Studies; D012307:Risk Factors; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12