Serum 25-hydroxyvitamin D and cognitive performance in hospitalized older adults: a cross-sectional study from Central Poland

Abstract

Introduction Dementia constitutes a major and rapidly growing public health challenge worldwide. The identification of its risk factors and potential contributors has therefore become a major focus of research. This study aimed to investigate the association between serum 25(OH)D concentration and cognitive performance, as well as the odds of cognitive impairment and documented dementia in a hospitalized geriatric population. Materials and methods This cross-sectional study included 1,539 hospitalized individuals aged ≥60 years from Central Poland. Cognitive performance was assessed using the Mini-Mental State Examination (MMSE) and the Clock Drawing Test (CDT). The age- and education-adjusted MMSE score was used in the statistical analyses. The test-based adverse cognitive outcomes were defined separately as MMSE <24, based on the age- and education-adjusted MMSE score, and CDT < 6. Information on documented dementia was obtained from medical records. Univariate analysis was performed using Mann–Whitney U test for continuous variables and chi-square test for categorical variables. Multivariable logistic regression models were used to assess the associations between serum 25(OH)D concentration and MMSE < 24, CDT < 6, and documented dementia, with adjustment for age, sex, BMI, albumin concentration, depressive symptoms, and history of stroke. Results Vitamin D deficiency (<20 ng/mL) was present in 53.3% of participants, and only 27.6% had concentrations ≥30 ng/mL. Higher serum 25(OH)D concentration was associated with lower odds of MMSE < 24 (OR = 0.984; 95% CI: 0.973–0.994; p = 0.001), CDT < 6 (OR = 0.988; 95% CI: 0.978–0.998; p = 0.018), and documented dementia (OR = 0.980; 95% CI: 0.970–0.990; p < 0.001). These estimates correspond to approximately 11–18% lower odds of adverse cognitive outcomes per 10 ng/mL increase in serum 25(OH)D. Older age, higher depressive symptom burden, and history of stroke were associated with worse cognitive outcomes, whereas higher albumin concentration was associated with better cognitive performance. Conclusion Higher serum 25(OH)D concentration was associated with better cognitive performance and lower odds of cognitive impairment and documented dementia in hospitalized older adults. These findings should be interpreted as observational associations. Due to the cross-sectional design, causality cannot be inferred, and prospective studies are warranted.