HDAC9 and Parkinson disease: In mice, the inhibition of HDACi in the frontal cortex and hippocampus alleviated depressive behavior,51 dementia, and brain trauma.52 Patients suffering from neurological disorders such as depression, Parkinson’s disease (PD), and schizophrenia, have higher than normal levels of HDAC.53 Parkinson’s disease is associated with increased cell numbers of enterobacteria and potentially harmful pro-inflammatory Proteobacteria, especially Ralstonia, and a decrease in Prevotella53,54 and butyrate-producing Blautia, Coprococcus, and Roseburia.