Association between 25-hydroxyvitamin D levels and cognitive performance in middle-aged and older European men.
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.
Lee
David M
DM
ARC Epidemiology Unit, The University of Manchester, Manchester M13 9PT, UK. david.m.lee@manchester.ac.uk
Tajar
Abdelouahid
A
Ulubaev
Aslan
A
Pendleton
Neil
N
O'Neill
Terence W
TW
O'Connor
Daryl B
DB
Bartfai
Gyorgy
G
Boonen
Steven
S
Bouillon
Roger
R
Casanueva
Felipe F
FF
Finn
Joseph D
JD
Forti
Gianni
G
Giwercman
Aleksander
A
Han
Thang S
TS
Huhtaniemi
Ilpo T
IT
Kula
Krzysztof
K
Lean
Michael E J
ME
Punab
Margus
M
Silman
Alan J
AJ
Vanderschueren
Dirk
D
Wu
Frederick C W
FC
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
D014807:Vitamin D; C104450:25-hydroxyvitamin D