"Utsubyo" in Japanese is similar to major depressive disorder (MDD) as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). "Utsubyo (DSM-5)/major depressive disorder" was agreed upon in 2014; however, utsubyo was diagnosed in Japan before the DSM-5. It was called endogenous depression.
 Endogenous depression is a disease whereas MDD is a syndrome. A disease presupposes a physical cause underlying the symptoms. The basis of MDD does not have to be physical, it can be a depressive or sad event (depressive reaction) or a conflict repressed in the unconscious (depressive neurosis).
 Depression and sadness in endogenous depression are manifested in the area where the mind and body intersect. Vital depression, vital sadness, vital inhibition, inability to mourn, and primary suicidal ideation are different in quality from the depression experienced in daily life and are unresponsive to empathic or sympathetic support.
 The DSM term "loss of pleasure" refers to the unresponsiveness and nonreactivity of mood in endogenous depression. It is also called anhedonia. In particular, loss of consummatory pleasure has high sensitivity and specificity for endogenous depression and is an important indicator of the efficacy of antidepressants.
 Diagnosis of endogenous depression is for the purpose of treatment. Diagnosis, education, consent, and information of the procedure lead to a good outcome. Electroconvulsive therapy or tricyclic antidepressants and a psychotherapeutic attitude based on an understanding of the psychopathology of the disease are essential in treatment. Kasahara summarized this in little psychotherapy, and Okuma added that encouragement of the patient is contraindicated. In addition to the therapeutic significance of the diagnosis of endogenous depression itself, physical treatment and psychotherapeutic guidelines specific to the diagnosis were given. This is the utility of the concept of endogenous depression.
 Author's abstract