Silent mating type information regulation 2 homolog 1 (SIRT1) is a protein in the Sirtuin family, and recent studies suggested that SIRT1 protein could affect monoamine transmitter levels in the brain by activating MAO-A transcription, thus the dysregulation of SIRT1 may be involved in depression [13,14]. Here, SIRT1 is linked to major depressive disorder.