title: Vitamin D deficiency, cognitive impairment and dementia: a systematic review and meta-analysis.
abstract: BACKGROUND
  Recent preventive strategies for patients with cognitive impairment include the identification of modifiable somatic risk factors like vitamin D deficiency.
  
  
  METHODS
  A systematic literature research and meta-analysis were conducted to assess the association of cognitive impairment and vitamin D deficiency.
  
  
  RESULTS
  Data from cross-sectional and longitudinal studies suggest an association between cognitive impairment and vitamin D deficiency. Meta-analysis of 5 cross-sectional and 2 longitudinal studies comprising 7,688 participants showed an increased risk of cognitive impairment in those with low vitamin D compared with normal vitamin D (OR 2.39, 95% CI 1.91-3.00; p < 0.0001).
  
  
  CONCLUSIONS
  Methodological limitations of these studies comprise heterogeneity of study populations, different forms of cognitive assessment, the problem of reverse causality, different definitions of vitamin D deficiency and inconsistent control for confounders. As the value of vitamin D substitution in cognitive impairment remains doubtful, a long-time major placebo-controlled randomized trial of vitamin D supplementation in participants with mild cognitive impairment (MCI) should be started.
authors: Department of Psychiatry and Psychotherapy, Technische Universität München, Munich, Germany. thorleif.etgen@klinikum-traunstein.de
authors: Thorleif
authors: T
authors: Etgen
authors: Dirk
authors: D
authors: Sander
authors: Horst
authors: H
authors: Bickel
authors: Kerstin
authors: K
authors: Sander
authors: Hans
authors: H
authors: Förstl
mesh_terms: D060825:Cognitive Dysfunction / Q000209:etiology / Q000503:physiopathology*; D003704:Dementia / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D012307:Risk Factors; D014807:Vitamin D / Q000378:metabolism* / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000503:physiopathology*
chemical_list: D014807:Vitamin D