The development of Kraepelin's mature diagnostic concept of hebephrenia: a close reading of relevant texts of Hecker, Daraszkiewicz, and Kraepelin.

In developing his mature concept of hebephrenic dementia praecox (DP) in his 4th (1893) through 6th textbook editions (1899), Kraepelin worked from the hebephrenic syndrome first described by Hecker (1871) and then carefully studied by his student Daraszkiewicz (1892). Working under Kraepelin's supervision, Daraszkiewicz followed Hecker in emphasizing several key features of hebephrenia (distinctive deteriorative course, importance of silliness and minimal positive psychotic symptoms) but expanded the syndrome to include cases developing severe dementia, rejected the link to prodromal depressive and manic phases, and reduced the emphasis on thought disorder. Daraszkiewicz proposed a soft subtyping of hebephrenia based on level of deterioration, which Kraepelin adopted in his 4th edition with an additional emphasis on severe positive psychotic symptoms. In his 5th edition, Kraepelin created a third subform with even more pronounced and bizarre delusions and hallucinations. In his 6th edition, which contained his first articulation of DP, Kraepelin eliminated his hebephrenia subforms presenting a single syndrome, which, compared to Hecker, included more emphasis on positive psychotic and catatonic symptoms and severe dementia. Kraepelin's paths to hebephrenic and paranoid DP differed in important ways. Paranoid DP was a de novo syndrome created by differentiation from paranoia. Hebephrenia, by contrast, evolved from a disorder created in the Kahlbaum/Hecker paradigm of the iterative study of clinical features, course and outcome. Kraepelin further implemented this approach in substantially reworking, over several drafts, the hebephrenic syndrome to fit into his emerging construct of dementia praecox.