HDAC6 and Alzheimer disease: A sampling of evidence in support of this enzyme’s role in AD includes elevated HDAC-6 protein levels in AD brains (especially in the cortical and hippocampal regions) versus normal aged comparators, diminished tau phosphorylation in both HDAC-6 inhibition and knockdown studies, and cognitive improvement observations in cross studies of HDAC-6 knockdown versus amyloid beta (Aβ)-induced memory deficit models.