Relation of plasma lipids to Alzheimer disease and vascular dementia.

BACKGROUND: The relation between plasma lipid levels and Alzheimer disease (AD) and vascular dementia (VaD), and the impact of drugs to lower lipid levels remains unclear. OBJECTIVE: To investigate the relation between plasma lipid levels and the risk of AD and VaD and the impact of drugs to lower lipid levels on this relationship. DESIGN AND SETTING: Cross-sectional and prospective community-based cohort studies. PARTICIPANTS: Random sample of 4316 Medicare recipients, 65 years and older, residing in northern Manhattan, NY. MAIN OUTCOME MEASURES: Vascular dementia and AD according to standard criteria. RESULTS: Elevated levels of non-high-density lipoprotein (HDL-C) and low-density lipoprotein cholesterol (LDL-C) and decreased levels of HDL-C were weak risk factors for VaD in either cross-sectional or prospective analyses. Higher levels of total cholesterol were associated with a decreased risk of incident AD after adjustment for demographics, apolipoprotein E genotype, and cardiovascular risk factors. Treatment with drugs to lower lipid levels did not change the disease risk of either disorder. CONCLUSIONS: We found a weak relation between non-HDL-C, LDL-C, and HDL-C levels and the risk of VaD. Lipid levels and the use of agents to lower them do not seem to be associated with the risk of AD.