Indeed, various HDAC inhibitors have been demonstrated to prevent neuronal apoptosis induced by oxidative stress9 or DNA damage.10 Furthermore, nervous diseases, including Alzheimer's disease (AD), Parkinson's disease, Huntington's disease, ischaemia, haemorrhage, multiple sclerosis and Friedreich's ataxia, were ameliorated with obvious decreases in apoptosis after administration of HDAC inhibitors.8, 11 However, decreasing HAT activity also results in a loss of acetylation; the critical HAT member whose loss of activity contributes to neuronal apoptosis remains to be identified. Here, HDAC9 is linked to Alzheimer disease.