HDAC9 and major depressive disorder: Aβ aggregates [35,36,37,38,39,40,41,42,44,46], tau protein aggregates [38,39], AD-associated depression (SERT, 5-HT1AR) [34], metal dyshomeostasis (transition metals) [38,39,40,41,44,47], BACE1 [39], MAO-B [43], MAO-A [43], 5-HT6R [42], neuroinflammation (ROS [34,37,38,39,40,44,45,47], FAAH [36], UPS degradation pathway [41], HDAC [44], NRF2 [37,45], calcium channels [45])