Dementia 2.6 X more likely if very low Vitamin D
Vitamin D Insufficiency is Associated with Higher Incidence of Dementia, a Large Community-Based Retrospective Cohort Study
J Geriatr Psychiatry Neurol . 2023 Mar 8;8919887231163292. PDF behind paywall
David Kiderman 1 2, Niv Ben-Shabat 3 4, Avishai M Tsur 5 6, Saar Anis 7, Abdulla Watad 3 4 8, Arnon D Cohen 9 10, Ziv Paz 11 12, Howard Amital 3 4
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Introduction: Active metabolite of vitamin D has neuro-immunomodulatory and neuroprotective properties. However, there is still a debate about the potential association between low serum levels of hydroxy-vitamin D and increased risk for dementia.
Objectives: To determine an association between hypovitaminosis D and dementia for different 25-hydroxyvitamin-D (25(OH)D) serum level cutoffs.
Methods: Patients were identified utilizing the database of Clalit Health Services (CHS), the largest healthcare provider in Israel. For each subject, all available values of 25(OH)D during the study period, which lasted from 2002 to 2019, were obtained. Rates of dementia were compared across different cutoffs of 25(OH)D levels.
Results: Cohort included 4278 patients, of whom 2454 (57%) were women. The mean age at the beginning of follow-up was 53 (±17). During the 17-year study period, a total of 133 patients (3%) were diagnosed with dementia. In a fully adjusted multivariate analysis, the risk for dementia was almost 2-fold higher in patients with an average of vitamin D insufficiency (<75 nmol/l) measurements (OR = 1.8, 95% C.I. = 1.0-3.2) compared to reference values (=75 nmol/l).
Patients with vitamin D deficiency (<50 nmol/l) demonstrated higher rates of dementia ( OR = 2.6 , 95% C.I. = 1.4-4.8). In our cohort, patients were diagnosed with dementia at a younger age in the deficiency (77 vs. 81 P-value = 0.05) and the insufficiency groups (77 vs. 81 P-value = 0.05) compared to the reference values (=75 nmol/l).
Conclusion: Insufficient levels of vitamin D are associated with dementia. Dementia is diagnosed at a younger age in patients with insufficient and deficient vitamin D levels.
Extrapolation of the data: no increased risk of Dementia if 125 nmol

VitaminDWiki - Dementia is associated with low vitamin D - many studies 50+
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