In favor of the Aβ cascade theory we can say that mutations in genes involved in the genesis of Aβ cause AD [3,4]; mutations in the gene encoding the tau protein do not cause amyloid deposition [5,6]; the ApoE4 allele leads to a reduction in the clearance of the Aβ peptide and increases the risk of AD [7]; Aβ oligomers that are isolated from AD brains involve loss of synapses, neuronal density, and memory impairment [8]; Aβ peptide can induce hyper-phosphorylation of tau [9]. Here, APOE is linked to Alzheimer disease.