title: Association between 25-hydroxyvitamin D levels and cognitive performance in middle-aged and older European men.
abstract: BACKGROUND
  Although there is evidence that vitamin D inadequacy may be linked to adverse cognitive outcomes, results from studies on this topic have been inconsistent. The aim of this trial was to examine the association between 25-hydroxyvitamin D (25(OH)D) levels and cognitive performance in middle-aged and older European men.
  
  
  METHODS
  This population-based cross-sectional study included 3,369 men aged 40-79 years from eight centres enrolled in the European Male Ageing Study. Cognitive function was assessed using the Rey-Osterrieth Complex Figure (ROCF) test, the Camden Topographical Recognition Memory (CTRM) test and the Digit Symbol Substitution Test (DSST). Serum 25(OH)D levels were measured by radioimmunoassay. Additional assessments included measurement of physical activity, functional performance and mood/depression. Associations between cognitive function and 25(OH)D levels were explored using locally weighted and linear regression models.
  
  
  RESULTS
  In total, 3,133 men (mean (+/-SD) age 60+/-11 years) were included in the analysis. The mean (+/-SD) 25(OH)D concentration was 63+/-31 nmol/l. In age-adjusted linear regressions, high levels of 25(OH)D were associated with high scores on the copy component of the ROCF test (beta per 10 nmol/l = 0.096; 95% CI 0.049 to 0.144), the CTRM test (beta per 10 nmol/l = 0.075; 95% CI 0.026 to 0.124) and the DSST (beta per 10 nmol/l = 0.318; 95% CI 0.235 to 0.401). After adjusting for additional confounders, 25(OH)D levels were associated with only score on the DSST (beta per 10 nmol/l = 0.152; 95% CI 0.051 to 0.253). Locally weighted and spline regressions suggested the relationship between 25(OH)D concentration and cognitive function was most pronounced at 25(OH)D concentrations below 35 nmol/l.
  
  
  CONCLUSIONS
  In this study, lower 25(OH)D levels were associated with poorer performance on the DSST. Further research is warranted to determine whether vitamin D sufficiency might have a role in preserving cognitive function in older adults.
authors.affiliation: ARC Epidemiology Unit, The University of Manchester, Manchester M13 9PT, UK. david.m.lee@manchester.ac.uk
authors.forename: David M
authors.initials: DM
authors.lastname: Lee
authors.forename: Abdelouahid
authors.initials: A
authors.lastname: Tajar
authors.forename: Aslan
authors.initials: A
authors.lastname: Ulubaev
authors.forename: Neil
authors.initials: N
authors.lastname: Pendleton
authors.forename: Terence W
authors.initials: TW
authors.lastname: O'Neill
authors.forename: Daryl B
authors.initials: DB
authors.lastname: O'Connor
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Bartfai
authors.forename: Steven
authors.initials: S
authors.lastname: Boonen
authors.forename: Roger
authors.initials: R
authors.lastname: Bouillon
authors.forename: Felipe F
authors.initials: FF
authors.lastname: Casanueva
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Finn
authors.forename: Gianni
authors.initials: G
authors.lastname: Forti
authors.forename: Aleksander
authors.initials: A
authors.lastname: Giwercman
authors.forename: Thang S
authors.initials: TS
authors.lastname: Han
authors.forename: Ilpo T
authors.initials: IT
authors.lastname: Huhtaniemi
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kula
authors.forename: Michael E J
authors.initials: ME
authors.lastname: Lean
authors.forename: Margus
authors.initials: M
authors.lastname: Punab
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Silman
authors.forename: Dirk
authors.initials: D
authors.lastname: Vanderschueren
authors.forename: Frederick C W
authors.initials: FC
authors.lastname: Wu
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology; D000368:Aged; D000375:Aging / Q000097:blood / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D003430:Cross-Sectional Studies; D005060:Europe; D006801:Humans; D016014:Linear Models; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology*; D011863:Radioimmunoassay; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D