HDAC6 and Alzheimer disease: Of importance, HDAC6 expression has been shown to be elevated in AD patients (10,11), and HDAC6 activity is increased in a transgenic mouse model of Aβ amyloidosis, as well as primary hippocampal neurons exposed to Aβ1−42, indicating that Aβ may initiate the pathogenic cascade by increasing HDAC6 activity (8).