Vitamin d 3 (cholecalciferol) insufficiency has been associated with cognitive impairment and dementia. despite considerable study variability, recent meta-analyses 1,2 reported an overall significant relationship between vitamin d deficiency and lower global cognitive functioning as assessed by MiniMental Status exam (MMSe) scores 1,2 . Similarly, analyses of case control studies revealed that vitamin d levels are 6-15 nmol/l lower in alzheimer's patients than age-matched controls. Meta-analytic pooling of longitudinal studies 3,4 revealed that vitamin d deficient individuals had significantly increased odds of 2.5, 95% confidence interval (Cis) [1.74-3.56], p<0.0001, of incident cognitive impairment at follow-up 2 .AbStRAct: Background: Vitamin d3 (cholecalciferol) deficiency has been associated with dementia and cognitive decline. Which cognitive domains are most associated with d3 levels and how seasonal fluctuations in levels relate to cognition is unclear. We addressed these questions using a prospective observational study examining associations between d3 levels and cognition among individuals living in northern latitudes (54°n) nmol/l were associated with inferior working memory/executive functioning. While our findings require confirmation, they suggest that sufficient d3 levels should be maintained year-round, likely necessitating supplementation, at least during winter at higher latitudes. (otS), (µ= 0,50 ; ét= 1,9 versus µ= -2,11 ; ét= 2,6 ; p = 0,01), un test de mémoire à court terme/ des fonctions exécutives. Conclusions : un déficit en vitamine d3 et une diminution saisonnière ≥ 15 nmol/l étaient associés à une mémoire à court terme / des fonctions exécutives moindres. Bien que ces observations méritent confirmation, elles suggèrent que des niveaux suffisants de vitamine d3 devraient être maintenus toute l'année, ce qui nécessite vraisemblablement une supplémentation en vitamine d3, du moins pendant l'hiver, aux latitudes plus nordiques.Can J neurol Sci.

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