title: Reduced risk of Alzheimer's disease with high folate intake: the Baltimore Longitudinal Study of Aging.
abstract: BACKGROUND
  Study findings have suggested an association between Alzheimer's disease (AD) risk and several vitamins and have speculated about their use as preventive agents. Here, we examine whether total intake (intake from diet plus supplements) of antioxidant vitamins (E, C, carotenoids) and B vitamins (folate, B(6), and B(12)) is associated with a reduced risk of AD.
  
  
  METHODS
  Participants were 579 nondemented elderly volunteers from the Baltimore Longitudinal Study of Aging who completed dietary diaries and recorded supplement intake for a 7-day period. Cox regression was used to estimate the relative risk (RR) of AD associated with total vitamin intake categorized into levels above or below the Recommended Dietary Allowance (RDA).
  
  
  RESULTS
  After a mean follow-up of 9.3 years, AD developed in 57 participants. Higher intake of folate (RR, 0.41; 95% confidence interval [CI], 0.22 to 0.76), vitamin E (RR, 0.56; 95% CI, 0.30 to 1.06), and vitamin B(6) (RR, 0.41; 95% CI, 0.20 to 0.84) were associated individually with a decreased risk of AD after adjusting for age, gender, education, and caloric intake. When these 3 vitamins were analyzed together, only total intake of folate at or above the RDA (RR, 0.45; 95% CI, 0.21 to 0.97) was associated with a significant decreased risk of AD. No association was found between total intake of vitamins C, carotenoids, or vitamin B(12) and risk of AD.
  
  
  CONCLUSIONS
  These findings suggest that total intake of folate at or above the RDA is associated with a reduced risk of AD. Additional studies are necessary to further investigate whether folate or other(s) unmeasured factor(s) may be responsible for this reduction in risk.
authors: Department of Neurology, University of California Irvine, Irvine, CA, USA. mcorrada@uci.edu
authors: María M
authors: MM
authors: Corrada
authors: Claudia H
authors: CH
authors: Kawas
authors: Judith
authors: J
authors: Hallfrisch
authors: Denis
authors: D
authors: Muller
authors: Ron
authors: R
authors: Brookmeyer