The Impact of Vitamin D Deficiency on Cognitive and Neuromuscular Functions in Elderly Patients.

BACKGROUND/AIMS Vitamin D plays an important regulatory role in neuronal and neuromuscular signalling, partly through its effects on calcium homeostasis, neuroinflammatory pathways, and vitamin D receptor-mediated transcription in neurons and glial cells. Deficiency of vitamin D is common among older adults and has been associated with impaired cognitive performance, reduced neuromuscular function, and elevated inflammatory activity. This study aimed to investigate associations between serum 25-hydroxyvitamin D levels, cognitive performance, neuromuscular function, and inflammatory signalling markers in older adults.

METHODS A cross-sectional study was conducted over six months (March-August 2025) at Tikrit Teaching Hospital, enrolling 250 adults aged 65-85 years. Cognitive function was assessed using the Mini-Mental State Examination and Montreal Cognitive Assessment. Neuromuscular performance was evaluated by handgrip strength, gait speed, Timed Up and Go testing, bioelectrical impedance analysis, and electromyography. Serum 25-hydroxyvitamin D, calcium, phosphorus, parathyroid hormone, alkaline phosphatase, creatine kinase, C-reactive protein, and interleukin-6 were measured. Associations were analyzed using Pearson correlations and group comparisons.

RESULTS Vitamin D deficiency was prevalent in 62.0% of participants. Lower vitamin D levels were associated with reduced cognitive scores, weaker neuromuscular performance, altered calcium metabolism, and elevated inflammatory markers. Correlation analyses demonstrated moderate positive associations between vitamin D levels and cognitive and neuromuscular outcomes, and negative associations with inflammatory markers.

CONCLUSION Vitamin D deficiency in older adults is associated with impaired cognitive and neuromuscular function, potentially mediated by dysregulated calcium signalling and increased neuroinflammatory activity. These findings support a mechanistic link between vitamin D status and neuronal and neuromuscular communication pathways.