Abstract
This article introduces the concept proposed by the eminent second-generation Japanese psychopathologist Tadao Miyamoto in 1992 that the manic-depressive mixed state is the basic psychopathology of manic-depressive illness. When Kraepelin first established the dichotomy between schizophrenia and manic-depressive illness, mania and depression were placed in a symmetrical relationship. Now, in Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), manic-depressive illness is divided into two distinct categories: bipolar and related disorders, and depressive disorders. Miyamoto pointed out that even in the average depressed state there is a manic-depressive mixed state and listed the following findings. The depressed mood of depression is itself a major fluctuation, but is constantly subject to more or less subtle fluctuations or swaying. What occurs in association with the incessant fluctuations of mood dysphoria are restlessness, agitation, irritability, and excitement, which manifest in a unique way in combination with a depressive mood. In depressive delusions, ideations of belittlement are developed in an exaggerated manner. Miyamoto concluded that mixed states are not incidental or accessory to manic-depressive illness; on the contrary, they may form a core component of manic-depressive illness.