title: Plasma vitamin D levels and cognitive function in aging women: the nurses' health study.
abstract: BACKGROUND
  Vitamin D may play a role in preserving cognitive function. However, there is a paucity of prospective studies on the relationship between vitamin D and cognition with aging. The aim of this study was to examine the association between plasma levels of vitamin D and subsequent cognitive function.
  
  
  METHODS
  This is a prospective study including 1,185 women aged 60-70 years from the Nurses' Health Study, who had plasma 25-hydroxy-vitamin D levels measured in 1989-1990 and completed an initial Telephone Interview of Cognitive Status approximately 9 years later. Subsequently, three follow-up cognitive assessments were conducted at 1.5-2.0 years intervals. We used multivariable-adjusted linear regression to model initial cognitive function, and mixed linear regression to model change in cognitive function over time.
  
  
  RESULTS
  Lower vitamin D levels were associated with significantly worse cognitive function 9 years later. For example, the mean global composite score averaging all the cognitive tests was 0.20 lower (95% Confidence Interval (CI):-0.33,-0.08; p-trend=0.009) in women in the lowest quintile (median=14.1 ng/mL) compared with women in the highest quintile of vitamin D (median=38.4 ng/mL). The observed differences were equivalent to the effect estimates we found for women who were approximately 4-6 years apart in age. However, vitamin D levels were not significantly associated with subsequent cognitive decline during 6 years of follow-up.
  
  
  CONCLUSIONS
  Higher levels of plasma vitamin D in women aged 60-70 years were associated with better cognitive function about a decade later but were not associated with cognitive decline during 6 years of follow-up.
authors.affiliation: B. Bartali, New England Research Institutes, Epidemiology, 9 Galen St., Watertown, MA, Email: bbartali@neriscience.com, Phone number: 617-972-8350, Fax number: 617-924-0968.
authors.forename: B
authors.initials: B
authors.lastname: Bartali
authors.forename: E
authors.initials: E
authors.lastname: Devore
authors.forename: F
authors.initials: F
authors.lastname: Grodstein
authors.forename: J H
authors.initials: JH
authors.lastname: Kang
mesh_terms: D000368:Aged; D000375:Aging / Q000097:blood* / Q000523:psychology*; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000097:blood* / Q000503:physiopathology / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D015577:Geriatric Assessment; D006306:Health Surveys; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D009726:Nurses; D011446:Prospective Studies; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D