Serum 25-Hydroxyvitamin D and Cognitive Decline: A Longitudinal Study among Non-Demented Older Adults

Background/Aims: Very few studies have investigated the longitudinal association between serum levels of 25-hydroxyvitamin D [25(OH) D] and cognitive impairment not due to dementia. This longitudinal study analysed 25(OH) D and the risk of cognitive decline among non-demented older adults. Methods: A subsample of the ESTHER cohort study, aged >= 70 years, was assessed with the Cognitive Telephone Screening Instrument (COGTEL) and underwent 25(OH) D measurements standardized with a reference method (n = 1,302). After an average follow-up of 4.6 years, 527 participants had repeated COGTEL testing and were eligible for analysis. Linear regression models were used to assess longitudinal associations between 25(OH) D levels and cognitive function. Possible practice effects of repeated cognitive testing were addressed with the reliable change index. Results: A trend of a more pronounced cognitive decline with lower vitamin D levels was observed among both women and men, with a statistically significant difference in COGTEL scores in the lowest vitamin D quintile of the total sample. Conclusions: This study indicates that low levels of vitamin D might be associated with cognitive decline among non-demented elderly individuals and highlights the need for further large-scale prospective studies to clarify the potential role of vitamin D in cognitive function at an old age. (C) 2014 S. Karger AG, Basel