Journals of Gerontology: Medical ScienceS

HYPOVITAMINOSIS D is common among older adults, affecting up to 90 % of the elderly population ( 1). This is crucial in that results of epidemiological studies suggest that hypovitaminosis D is associated with cognitive function and Alzheimer ’ s d isease (AD) ( 2 – 7). From a physiological point of view, vitamin D is a steroid hormone that exhibits neurosteroid actions in the central nervous system ( 8 – 10) , and it has been proposed that the chronic defi cit of vitamin D neurotrophic, anti-infl ammatory as well as antioxidant properties may par-tially explain neuronal degeneration and AD ( 10). Correction of hypovitaminosis D may potentially protect older adults against cognitive decline. To date, no randomized placebo-controlled trial has explored yet the benefi ts of vita-min D supplementation to treat or prevent dementia ( 10). Prior to planning such a resource-consuming supplementation trial, considering the contribution of exogenous vitamin D in the die