Vitamin D, systemic inflammation, and motoric cognitive risk: exploring the risk factors and mediation pathways.

Introduction: Motoric cognitive risk (MCR) syndrome, defined by subjective cognitive complaints and slow gait, is a predementia condition associated with multiple adverse outcomes. Although vitamin D deficiency and systemic inflammation have been implicated in cognitive and motor decline, their interaction in the context of MCR remains unclear. Methods: This cross-sectional study included 312 hospitalized adults aged ≥60 years. Serum 25(OH)D levels, systemic immune-inflammation index (SII), and standardized clinical assessments were obtained within 48 h of admission. Multivariable regression and mediation analyses were performed to evaluate associations and underlying pathways. Results: The prevalence of MCR was 17.9%. Older age, greater comorbidity burden, poor sleep quality, lower 25(OH)D levels, and higher SII were independently associated with MCR. Mediation analysis showed that systemic inflammation accounted for approximately one-quarter of the association between lower 25(OH)D and higher MCR risk, with the strongest indirect effect observed at 25(OH)D ≤ 20 ng/mL. Discussion: Vitamin D deficiency and systemic inflammation are important determinants of MCR. The identified vitamin D-inflammation pathway may contribute to motoric cognitive vulnerability and provide insights for early risk stratification and preventive strategies in geriatric populations.