VDR and vitamin D deficiency: Vitamin D deficiency may be involved in AD development because of the lack of vitamin D-driven protective effects related to the enhancement of clearance and phagocytosis of amyloid-beta (Aβ) peptide across the blood–brain barrier [78], and the prevention of cortical neurons degeneration induced by Aβ through LVCC down-regulation mediated by VDR up-regulation [56,79].