Origin and development of concepts of bipolar mixed states.

This paper reviews the historical origins of the contemporaneous resurgence of interest in mixed states. This is a classical concept whose origins can be traced back to ancient times. In more modern times, already in the pre-Kraepelinian era we can find descriptions and classifications of "mixed states". For example, in his classification of mental disorders described "mixtures of exaltations and depression", and he distinguished among "mixed mood disorders", "mixed mental disorders", and "mixed volition disorders". Subsequently, (the father of empirical and biological psychiatric research in Germany) described the "mid-forms". Half a century later we encounter the crucial role of Emil Kraepelin and the development and systemization of his views between 1899 and 1913--leading to the characterization of such conditions as "depressive-anxious mania", "excited depression", and "stuporous mania". The remainder of this article focuses on the essential points of the first book on mixed states in the psychiatric literature: On The Mixed States of Manic-Depressive Insanity by. For much of the present 20th century nothing new emerges, followed by a contemporary renaissance of mixed states, particularly in the United States. The paper concludes with proposal of mixed states as temperament intruding into an episode of opposite polarity.