Finally, elevated expression levels of Vitamin D receptor and 24-hydroylase mRNA in rat hippocampal versus cortical neurons [19] also supports that Vitamin D is particularly important for calcium metabolism and function of hippocampal neurons and supports evidence that localised impairment of Vitamin D uptake in the hippocampus, which is affected in early stages of AD, can account for loss of cellular function including memory in AD patients. This evidence concerns the gene VDR and Alzheimer disease.