DKK1 and Alzheimer disease: For example, HBO1 increases the activity of β-catenin in the Wnt signaling pathway in both the J82 and T24 cells [50], and either a reduced β-catenin in AD or the Wnt inhibitor Dkk1 (Dickkopf-1) positively regulates tau phosphorylation and exacerbates the cognitive deficits, establishing a link between HBO1 and AD [51, 52].