The Development of Kraepelin's Mature Diagnostic Concepts of Paranoia (Die Verrücktheit) and Paranoid Dementia Praecox (Dementia Paranoides): A Close Reading of His Textbooks From 1887 to 1899.

Over 12 years (1887-1899), in his second through sixth editions of his textbook Psychiatrie: Ein Lehrbuch für Studierende und Ärzte, Emil Kraepelin created, through an iterative, self-examining process, his mature concepts of Verrücktheit (paranoia) and Paranoide Formen Dementia Praecox. I seek in this essay to show this skilled nosologist at work. Four themes were prominent. First, Kraepelin used symptoms throughout, but he transitioned from superficial phenomenon (delusional themes) to those he considered more pathognomonic: disorganized fantastical delusions vs organized, nonbizarre delusions. Second, he increasingly emphasized the distinction between delusions arising from misinterpretations of real events vs delusions arising from hallucinations. Third, the putative causes of the disorder became more important as he came to understand Verrücktheit from a psychological and developmental perspective, whereas dementia paranoides (the precursor to paranoide formen dementia praecox) resulted from pathological brain changes. Fourth, Kraepelin appreciated the importance of disease course, but he initially lacked adequate data to elucidate it. As his research program developed, he used the well-recognized disease of general paralysis of the insane as a paradigm and correlated symptoms, modes of delusion formation, and presumed mechanisms of disease with course and outcome. Patients with slowly developing, referential, nonbizarre delusions without hallucinations were typically stable for years with minimal deterioration. Patients with rapidly developing, poorly organized, fantastical delusions emerging from prominent hallucinations tended to deteriorate quickly. Using conceptual tools first proposed by Kahlbaum and Hecker, Kraepelin developed his concepts of Verrücktheit and paranoide formen dementia praecox using an exploratory, conceptual, and data-gathering process in which each syndrome was defined in contrast to the other and, in addition to a core focus on disease course, multiple additional levels of clinical inquiry were included.