DKK1 and Alzheimer disease: Crucially, synapse loss as a response to Dkk1 exposure was reversible in vitro and in vivo, where synapse number and function was restored following removal of Dkk1 by washout or by cessation of Dkk1 over-expression [111,121], indicating that the normalisation of Wnt signalling may enable restoration of synapses in AD patients.