HDAC9 and Alzheimer disease: This result supports the fact that the available pharmaceutical therapies such as an acetylcholinesterase inhibitor and glutamate receptor antagonist can only ameliorate cognition of AD patients but fail to reverse the AD pathology [40]; while, the HDAC inhibitor, which affects transcriptional activity, is able to enhance neuronal survival and slow or prevent progressive neurodegeneration [33] and it has beneficial effects on learning and memory [10].