Background: Older adults with hypovitaminosis D report more often subjective cognitive complaints, especially with regards to memory. This raises prospects that vitamin D may improve older adults' subjective experience of memory disorders.
Objective: To determine among older community-dwellers whether higher serum 25- hydroxyvitamin D (25OHD) concentrations were associated with fewer memory complaints, while considering different subtypes of memory complaints.
Method: One hundred eighty Caucasian community-dwellers with memory complaint and no dementia (mean±standard deviation, 71.1±3.4years; 33.3%female) from the French ‘EVATEM study' were included in this analysis. Subjective memory complaints regarding memory lapses, problems learning new information, problems finding words, problems calculating and problems concentrating were assessed using a standardized questionnaire. Participants were categorized according to the highest tertile of serum 25OHD (i.e., ≥68nmol/L). Age, gender, body mass index, morbidities burden, use of vitamin D supplements, cognitive performance, mood, serum concentrations of calcium, parathyroid hormone and vitamin B12, creatinine clearance, and season of evaluation were used as potential confounders.
Results: Compared to participants with 25OHD<68nmol/L (n=121), those with 25OHD≥68nmol/L had less often problems learning new information (P=0.027). There were no between-group differences for the other memory complaints. The highest 25OHD tertile was cross-sectionally associated with fewer problems learning new information (odds ratio (OR)=0.48, P=0.029), even after adjustment for potential confounders (OR=0.32, P=0.039).
Conclusion: Higher vitamin D status was associated with reduced problems memorizing new information in older community-dwellers. This novel finding provides a scientific base for vitamin D replacement trials attempting to improve older patients' subjective experience of cognitive decline.
Keywords: Cognition, dementia, learning, subjective memory complaint, neuroendocrinology, older adults, vitamin D.