Previously, we reported that a small number (∼1 in 15) of Alzheimer’s disease brain aqueous extracts disrupt LTP in a tau-dependent and Aβ-independent manner.34 Before testing the facilitation of LTD, we first confirmed that a relatively weak LFS conditioning protocol10 was just below the threshold for inducing stable hippocampal LTD in vivo. This evidence concerns the gene MAPT and Alzheimer disease.