Lipids play an important part as risk or protective factors for Alzheimer's disease. This review summarizes the current findings in which lipids influence Alzheimer's disease and introduces the molecular mechanism how these lipids are linked to amyloid production. Besides the pathological impact of amyloid in Alzheimer's disease, amyloid has a physiological function in regulating lipid homeostasis in return. The understanding of the resulting regulatory cycles between amyloid precursor protein processing and lipids provides a platform for the development of new causal therapeutic approaches for Alzheimer's disease.