DKK1 and Alzheimer disease: First, LRP6 is dysregulated in the AD brain.165 LRP6 is downregulated in the AD brain, and deficiency in LRP6-mediated Wnt/β-catenin signalling contributes to synaptic dysfunction and amyloid pathology in AD.165 Second, DKK1 upregulation suppresses Wnt/β-catenin signalling in the AD brain.