ABSTRACT
Major depressive disorder （MDD） is an affective disorder characterized by significant and long-lasting depression， hypoactivity， and thinking and cognitive retardation. Some patients may conduct self-hram or suicide and have delusion， hallucination， and other mental symptoms. MDD is believed to be correlated with brain and heart， but there is no complete theory or mechanism fully explaining the pathogenesis of MDD. Traditional Chinese medicine （TCM） holds that the brain and heart dominate the formation of and change in mind， and MDD falls into the category of mental disease. It is mainly diagnosed as depression， visceral agitation， or Lily disease. Triple energizer is a key zang-fu organ that governs Qi transformation. There has always been some controversy about its anatomical structure. In recent years， important progress has been made in the research on the substantive structure of triple energizer. It is found that the structure and function of triple energizer are highly consistent to those of "mesenchyme"， a fluid space supported by a complex network of collagen fibers and widely distributed throughout the body. Different from known tissues and organs， it is a large organ responsible for information communication， material exchange， and energy metabolism. The triple energizer is partially contained in the structure of brain and heart and connects with the brain and heart， thus forming a "brain-heart-triple energizer" system with close physiological and pathological connections. With the association of "brain-heart-triple energizer" as the basis and Qi transformation as the core link， this paper elucidated the pathogenesis of MD and put forward that MDD resulted from "brain and heart Yang deficiency and Qi depression due to triple energizer obstruction"， so as to improve TCM understanding of the pathogenesis of MDD and perfect the TCM theories of encephalopathy and triple energizer.