title: The association between vitamin D and cognition: a systematic review.
abstract: Vitamin D insufficiency and deficiency are a major health care problem. The association between vitamin D levels and cognitive function is still under debate. We conducted a systematic review to assess the association between levels of vitamin D and cognition. Therefore, the databases of Embase and Pubmed were searched through June 2012 for observational studies relating vitamin D levels to cognition. Our initial search yielded 2182 articles. After applying exclusion criteria, there were 28 studies eligible for inclusion: 25 cross-sectional and 6 prospective studies (3 studies show cross-sectional as well as prospective data). The main finding of the 25 cross-sectional studies was a statistically significant worse outcome on one or more cognitive function tests or a higher frequency of dementia with lower vitamin D levels or intake in 18 out of 25 (72%) studies, whereas 7 (28%) studies failed to show an association. Four out of 6 (66.7%) prospective studies showed a higher risk of cognitive decline after a follow-up period of 4-7 years in participants with lower vitamin D levels at baseline. In conclusion, this review supports the hypothesis that hypovitaminosis D is associated with worse outcome on one or more cognitive function tests or a higher frequency of dementia in cross-sectional as well as prospective studies. Further studies should focus on the role of vitamin D supplementation in the prevention of cognitive decline in participants with low vitamin D levels.
authors.affiliation: Department of Geriatrics, University Medical Center Utrecht, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: van der Schaft
authors.forename: H L
authors.initials: HL
authors.lastname: Koek
authors.forename: E
authors.initials: E
authors.lastname: Dijkstra
authors.forename: H J J
authors.initials: HJ
authors.lastname: Verhaar
authors.forename: Y T
authors.initials: YT
authors.lastname: van der Schouw
authors.forename: M H
authors.initials: MH
authors.lastname: Emmelot-Vonk
mesh_terms: D000818:Animals; D003071:Cognition / Q000187:drug effects / Q000502:physiology*; D003072:Cognition Disorders / Q000097:blood* / Q000175:diagnosis / Q000523:psychology; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D006801:Humans; D014807:Vitamin D / Q000008:administration & dosage* / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000175:diagnosis / Q000523:psychology
chemical_list: D014807:Vitamin D
keywords: Cognition; Deficiency; Systematic review; Vitamin D