title: Folate, vitamin B-6, and vitamin B-12 intake and mild cognitive impairment and probable dementia in the Women's Health Initiative Memory Study.
abstract: BACKGROUND
  Whether higher B vitamin intake (ie, B-6, B-12, and folate) is protective against cognitive decline in later life remains uncertain. Several prospective, observational studies find higher B vitamin intake to be associated with lower risk of dementia; other studies, including most trials of B vitamin supplementation, have observed no effect on cognition. We examined this question in a large population of older women carefully monitored for development of mild cognitive impairment (MCI) and probable dementia.
  
  
  OBJECTIVE
  To determine whether baseline folate, vitamin B-6, and/or vitamin B-12 intake, alone or in combination, are associated with incident MCI/probable dementia among older women.
  
  
  METHODS
  Prospective, longitudinal cohort study. Participants were enrolled between 1993 and 1998, and B vitamin intake was self-reported using a food frequency questionnaire administered at baseline.
  
  
  METHODS
  Postmenopausal women (N=7,030) free of MCI/probable dementia at baseline in the Women's Health Initiative Memory Study.
  
  
  METHODS
  Over a mean follow-up of 5.0 years, 238 cases of incident MCI and 69 cases of probable dementia were identified through rigorous screening and expert adjudication.
  
  
  METHODS
  Cox proportional hazard models adjusting for sociodemographic and lifestyle factors examined the association of B vitamin intake above and below the Recommended Daily Allowance and incident MCI/probable dementia.
  
  
  RESULTS
  Folate intake below the Recommended Daily Allowance at study baseline was associated with increased risk of incident MCI/probable dementia (hazard ratio 2.0, 95% CI 1.3 to 2.9), after controlling for multiple confounders. There were no significant associations between vitamins B-6 or B-12 and MCI/probable dementia, nor any evidence of an interaction between these vitamins and folate intake.
  
  
  CONCLUSIONS
  Folate intake below the Recommended Daily Allowance may increase risk for MCI/probable dementia in later life. Future research should include long-term trials of folic acid supplementation to examine whether folate may impart a protective effect on cognition in later life.
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Agnew-Blais
authors.forename: Sylvia
authors.initials: S
authors.lastname: Wassertheil-Smoller
authors.forename: Jae H
authors.initials: JH
authors.lastname: Kang
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Hogan
authors.forename: Laura H
authors.initials: LH
authors.lastname: Coker
authors.forename: Linda G
authors.initials: LG
authors.lastname: Snetselaar
authors.forename: Jordan W
authors.initials: JW
authors.lastname: Smoller
mesh_terms: D000368:Aged; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008875:Middle Aged; D009043:Motor Activity; D016016:Proportional Hazards Models; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D012959:Socioeconomic Factors; D016896:Treatment Outcome; D014805:Vitamin B 12 / Q000008:administration & dosage*; D025101:Vitamin B 6 / Q000008:administration & dosage*
chemical_list: D025101:Vitamin B 6; D005492:Folic Acid; D014805:Vitamin B 12
keywords: Cognitive impairment; Dementia; Folic acid; Vitamin B-12; Vitamin B-6