INS and Alzheimer disease: In this section, we summarize the biological features of lipid metabolism to provide a comprehensive overview of the intrinsic mechanisms by which lipid metabolism regulates Aβ protein deposition, tau protein hyperphosphorylation, and insulin resistance and emphasize its important role in the pathogenesis and progression of AD, DCI and VD, providing novel insights and approaches for the prevention and treatment of these types of dementia.