title: Vitamin D and cognitive function: The Tromsø Study.
abstract: OBJECTIVE
  There are indications that vitamin D may be important for more than skeletal health, including cognitive function.
  
  
  METHODS
  The study was performed in Tromsø, Northern Norway (The Tromsø Study). In a cross-sectional study serum 25-hydroxyvitamin D (25(OH)D) was measured and cognitive function (word recall, digit-symbol coding, finger tapping, Mini Mental State Examination) tested in 4624 subjects; in a prospective study serum 25(OH)D was measured in samples from 1994 and compared to cognitive function tested in 3436 subjects in 2001 and 2044 subjects in 2007; and in a Mendelian randomization study single nucleotide polymorphisms (SNPs) related to vitamin D were evaluated versus cognitive function in 5980 subjects.
  
  
  RESULTS
  In the cross-sectional study all tests were positively associated with serum 25(OH)D levels with ~5% better performance in subjects in the highest versus lowest serum 25(OH)D quartile. This relation was only seen in subjects older than 65 years. After full adjustment for season, age, gender, body mass index, blood pressure, physical activity and education, the relation was only significant for finger tapping. In the prospective study, serum 25(OH)D from 1994 similarly predicted cognitive function 7-13 years later. In the Mendelian randomization study, only one SNP in the VDR gene (Apal, rs7975232) was significantly associated with cognition (word recall and digit-symbol coding).
  
  
  CONCLUSIONS
  There is an association between serum 25(OH)D and cognition, but randomized controlled trials are needed to establish causality.
authors.affiliation: Tromsø Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway; Division of Internal Medicine, University Hospital of North Norway, 9038 Tromsø, Norway; The School of Population Health, University of Auckland, Auckland, New Zealand. Electronic address: rolf.jorde@unn.no.
authors.forename: Rolf
authors.initials: R
authors.lastname: Jorde
authors.affiliation: Brain and Circulation Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Norway; Department of Neurology and Neurophysiology, University Hospital of North Norway, 9038 Tromsø, Norway. Electronic address: ellisiv.mathiesen@ism.uit.no.
authors.forename: Ellisiv Bøgeberg
authors.initials: EB
authors.lastname: Mathiesen
authors.affiliation: Division of Internal Medicine, University Hospital of North Norway, 9038 Tromsø, Norway. Electronic address: sigrogne@online.no.
authors.forename: Sigbjørn
authors.initials: S
authors.lastname: Rogne
authors.affiliation: Department of Community Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway. Electronic address: tom.wilsgaard@ism.uit.no.
authors.forename: Tom
authors.initials: T
authors.lastname: Wilsgaard
authors.affiliation: Tromsø Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway; Division of Internal Medicine, University Hospital of North Norway, 9038 Tromsø, Norway. Electronic address: marie.kjaergaard@unn.no.
authors.forename: Marie
authors.initials: M
authors.lastname: Kjærgaard
authors.affiliation: Tromsø Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway; Division of Internal Medicine, University Hospital of North Norway, 9038 Tromsø, Norway. Electronic address: guri.grimnes@unn.no.
authors.forename: Guri
authors.initials: G
authors.lastname: Grimnes
authors.affiliation: Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway; Division of Cardiothoracic and Respiratory Medicine, University Hospital of North Norway, 9038 Tromsø, Norway. Electronic address: h.schirmer@ucl.ac.uk.
authors.forename: Henrik
authors.initials: H
authors.lastname: Schirmer
mesh_terms: D000368:Aged; D003071:Cognition / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D005838:Genotype; D006801:Humans; D016014:Linear Models; D008297:Male; D057182:Mendelian Randomization Analysis; D008609:Mental Status Schedule; D008875:Middle Aged; D009483:Neuropsychological Tests; D009664:Norway; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D018167:Receptors, Calcitriol / Q000235:genetics; D012189:Retrospective Studies; D012907:Smoking / Q000453:epidemiology; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D018167:Receptors, Calcitriol; C579457:VDR protein, human; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: Cognition; Mendelian randomization; Polymorphisms; Prospective study; Vitamin D; Vitamin D receptor