Manic-Depressive Illness: Evolution in Kraepelin's Textbook , 1883–1926

BACKGROUND: The syndrome of manic-depressive insanity (MDI), as conceptualized by Emil Kraepelin a century ago, with later refinements, continues to dominate research and clinical practice with mood disorder patients. Current understanding of Kraepelin's views by Anglophones is heavily influenced by the late, highly developed, MDI concept represented in the 1921 partial English translation of the last complete edition of his textbook, the product of gradual development over several decades. METHOD: We reviewed all nine editions and revisions of Kraepelin's Textbook (1883-1926) and other writings by him to document the evolution of his views of MDI, and characterized salient developments within biographical and historical contexts. RESULTS: We found support for the traditional impression that Kraepelin's clinical perception of similarities of various forms of periodic psychiatric disorders marked by fundamental dysregulation of excitation and inhibition of thought and behavior, as well as of mood--as distinct from chronic psychotic illnesses--encouraged his broad, mature concept of MDI. However, our findings indicate a complex evolution of Kraepelin's MDI concept in the 1880s and 1890s, his use of more creative and less empirical clinical methods than traditionally believed, and his considerable personal uncertainty about making clear distinctions among MDI, dementia praecox, intermediate conditions, and paranoid disorders--an uncertainty that persisted to the end of his career in the 1920s. CONCLUSIONS: Kraepelin responded to a compelling international need for diagnostic order in nineteenth-century psychiatry, and effectively promoted his diagnostic proposals with a widely used and influential textbook. Though his methods were less empirical than is usually realized, his legacy includes analysis of large clinical samples to describe psychopathology and illness-course, along with efforts to define psychobiologically coherent and clinically differentiable entities, as steps toward defining psychiatric syndromes. Modern international "neo-Kraepelinian" enthusiasm for descriptive, criterion-based diagnosis should be tempered by Kraepelin's own appreciation of the tentative and uncertain nature of psychiatric nosology, particularly in classifying illnesses with both affective and psychotic features.