MAPT and Alzheimer disease: To our knowledge, this is the first study to examine p-tau181 in synapses, however, previous work has reported elevations of p-tau S396/404 and S202 in AD cases SN,83 as well as misfolded and hyperphosphorylated tau in both AD and age-control SN.124 The current study shows that p-tau181 is present within synapses in both ageing and in AD.