Vitamin D is associated with cognitive status in patients with Alzheimer’s disease

Abstract

Introduction: Previous studies have reported an association between low 25-hydroxyvitamin D (25(OH)D) levels and cognitive impairment. However, this association has not been reported in Turkish patients with cognitive impairment. We investigated this relationship in Turkish patients diagnosed with Alzheimer’s disease (AD). Materials and Method: Seventy-two patients with a diagnosis of “Probable AD” were included in the study. Demographic and disease specific characteristics were recorded. Cognitive performance was assessed using the Mini-mental State Examination (MMSE). Patients were categorized into two groups with regard to their 25(OH)D levels based on the recommended cut-off value (30 ng/ml) for 25(OH)D insufficiency. Association between 25(OH)D levels and MMSE scores was assessed using a regression model taking probable confounding factors into account. Results: Sixty-nine patients were included in the final analysis. Patients with 25(OH)D levels higher than 30 ng/ml performed (n=18) significantly better in MMSE than the group with lower values (n=51) (p=0.027). Subsequently, the multiple linear regression analysis showed a significant association between 25(OH)D levels and MMSE scores; this association was independent of the confounding effects of age, gender, education, disease duration, anti-dementia medication and depressive state (B= 2.81, p=0.04). Conclusion: Our results support that low 25(OH)D levels are associated with worse cognitive performance in Turkish patients with AD. Larger population-based studies are required to clarify this relationship in Turkish population not only in patients with AD, but also in individuals with mild cognitive impairment and healthy elderly.