HDAC9 and neurodegenerative disease: In fact, the SB-mediated improvement is correlated with elevated brain dopamine levels and HDAC inhibitors can be considered applicable in the treatment of neurodegenerative diseases where acetylation homeostasis is significantly destroyed, leading to a reduction in the histone acetylation level and a disrupted the HDAC/HAT (histone acetyltransferases) balance [224].