Apolipoprotein E4 promotes incipient Alzheimer pathology in the elderly

To evaluate the influence of the apolipoprotein E (ApoE) epsilon 4 allele on the age at which Alzheimer-like lesions appear in the brain, we analyzed the degree of cerebral beta-amyloidosis and neurofibrillary tangle formation in the hippocampal formation and adjacent cortical areas 28, 27, and 36 of persons who had died between the ages of 50 and 93 years and who had shown no signs of clinical dementia. The occurrence of the three common polymorphisms of the ApoE gene in this sample of 147 routine autopsy cases from eastern Germany was comparable to previously reported values in European and North American populations: ApoE epsilon 2/2, 0.7%; ApoE epsilon 2/3, 14.3%; ApoE epsilon 2/4, 4.1%; ApoE epsilon 3/3, 56.5%; ApoE epsilon 3/4, 22.4%; and ApoE epsilon 4/4, 2.0%. Nondemented persons carrying the ApoE epsilon 4 allele were significantly more likely to have senile plaques, diffuse amyloid deposits, cerebrovascular amyloid and neurofibrillary tangles than were those lacking epsilon 4. Comparing the two largest ApoE subgroups, ApoE epsilon 3/3 and ApoE epsilon 3/4, the relative increase in the occurrence of beta-amyloid in the epsilon 3/4 group was evident by the mid-60s, with the relative increase in neurofibrillary tangles in this group emerging slightly earlier. The ApoE epsilon 2 allele appears to delay the appearance of the lesions somewhat. We conclude that ApoE epsilon 4, promotes the early appearance of beta-amyloid and neurofibrillary tangles in the elderly and that the increased frequency of these lesions is related to the higher risk of Alzheimer disease in persons bearing the ApoE epsilon 3 allele.