Chapter 12 - Apolipoprotein E and Alzheimer's disease

Abstract

This chapter discusses various aspects of apolipoprotein E and Alzheimer's disease (AD). Apolipoprotein E (ApoE) is a polymorphic protein associated with plasma lipoproteins. It interacts with the remnant receptor and the LDL receptor of the liver and other organs, to modulate the catabolism of triglyceride-rich lipoprotein particles. It is observed that in addition to the transport of cholesterol required for synaptogenesis, ApoE could also affect the cholinergic activity of the hippocampus through the availability of precursor lipid in the synthesis of acetylcholine. There is a highly significant correlation between the ApoE4 allele frequency and the AD prevalence in six different countries for which allele frequencies and AD prevalence values are currently available. There is no correlation between the ApoE3 and ApoE2 allele frequencies and AD prevalence in those same regions. The observation suggests that the well-established association between ApoE4 and AD is not population specific but represents a worldwide effect of genetic aetiology. The interactions between ApoE4 and Aβ appear to be closely related to the formation of amyloid plaques and could play a role in the pathophysiological process leading to AD.