Vitamin D Insufficiency is Associated with Higher Incidence of Dementia, a Large Community-Based Retrospective Cohort Study

Abstract

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.