Catatonia as a putative nosological entity: A historical sketch.

Kahlbaum was the first to propose catatonia as a separate disease following the example of general paresis of the insane, which served as a model for establishing a nosological entity. However, Kahlbaum was uncertain about the nosological position of catatonia and considered it a syndrome, or "a temporary stage or a part of a complex picture of various disease forms". Until recently, the issue of catatonia as a separate diagnostic category was not entertained, mainly due to a misinterpretation of Kraepelin's influential views on catatonia as a subtype of schizophrenia. Kraepelin concluded that patients presenting with persistent catatonic symptoms, which he called "genuine catatonic morbid symptoms", particularly including negativism, bizarre mannerisms, and stereotypes, had a poor prognosis similar to those of paranoid and hebephrenic presentations. Accordingly, catatonia was classified as a subtype of dementia praecox/schizophrenia. Despite Kraepelin's influence on psychiatric nosology throughout the 20 century, there have only been isolated attempts to describe and classify catatonia outside of the Kraepelinian system. For example, the Wernicke-Kleist-Leonhard school attempted to comprehensively elucidate the complexities of psychomotor disturbances associated with major psychoses. However, the Leonhardian categories have never been subjected to the scrutiny of modern investigations. The first three editions of the DSM included the narrow and simplified version of Kraepelin's catatonia concept. Recent developments in catatonia research are reflected in DSM-5, which includes three diagnostic categories: Catatonic Disorder due to Another Medical Condition, Catatonia Associated with another Mental Disorder (Catatonia Specifier), and Unspecified Catatonia. Additionally, the traditional category of catatonic schizophrenia has been deleted. The Unspecified Catatonia category could encourage research exploring catatonia as an independent diagnostic entity.