*Review* **Epigenetic Targeting of Histone Deacetylases in Diagnostics and Treatment of Depression**

**Hyun-Sun Park 1,\*, Jongmin Kim 2,3 , Seong Hoon Ahn <sup>4</sup> and Hong-Yeoul Ryu 5,\***


**Abstract:** Depression is a highly prevalent, disabling, and often chronic illness that places substantial burdens on patients, families, healthcare systems, and the economy. A substantial minority of patients are unresponsive to current therapies, so there is an urgent need to develop more broadly effective, accessible, and tolerable therapies. Pharmacological regulation of histone acetylation level has been investigated as one potential clinical strategy. Histone acetylation status is considered a potential diagnostic biomarker for depression, while inhibitors of histone deacetylases (HDACs) have garnered interest as novel therapeutics. This review describes recent advances in our knowledge of histone acetylation status in depression and the therapeutic potential of HDAC inhibitors.

**Keywords:** histone deacetylase (HDAC); depression; biomarker; anti-depressant therapy
