However, evidence is accumulating that dysfunctional Wnt signaling activities, such as a reduction in the levels of β-catenin, constitutively active GSK-3β, and increasing expression of Wnt signaling inhibitor, DKK-1, are associated with AD pathology [2, 5, 8, 20–22, 62, 63]. This evidence concerns the gene DKK1 and Alzheimer disease.