ABO and Alzheimer disease: Given that Aβo enhance LTD and that LTD requires tau phosphorylation (Regan et al., 2015), we hypothesized that there may be a connection between synaptic changes induced by Aβo and tau hyperphosphorylation in AD, with LTD, or a pathological LTD-like process, serving as a potential mechanistic link between the two.