Dementia affects an estimated 10% of the population older than 65 years. Because vascular and lipid-related mechanisms are thought to have a role in the pathogenesis of Alzheimer's disease and vascular dementia, we did an epidemiological study of the potential effect of HMGCoA (3 hydroxy-3methylglutaryl-coenzyme A) reductase inhibitors (statins) and other lipid-lowering agents on dementia.