NPC1 and Alzheimer disease: In contrast to the controversial role of changes in total brain cholesterol levels in AD [2, 14], our findings on the expression of putative intracellular cholesterol carriers (e.g. STARD1 and NPC1) in patients with AD and DS correlate with disease markers, such as Aβ42, and suggest that alterations in intracellular cholesterol homeostasis may be an early molecular event that favours the progression of the AD pathology.