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4. Contributions of German Neuroscience to the Concept of Alzheimer Disease
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4 Contributions of German Neuroscience to the Concept of Alzheimer Disease Hans Förstl During the first half of the twentieth century, the concept of Alzheimer disease was written about entirely in German. A new staining method described by Bielschowsky (1903) allowed Alois Alzheimer to demonstrate a new kind of argentophilic intraneuronal fibrillary tangle (1906, 1907) in his first patient with the severe form of presenile dementia that came to be known as Alzheimer disease (AD). This short story of a serendipitous observation has a prehistory that may clarify why a single brief case study on a degenerative form of dementia made history, while whole monographs written at the same time about closely related topics are almost forgotten (Leri 1906; Pick 1898). Research on progressive paralysis had led to a number of important discoveries during the previous decade. A. Pick (1892, 1898, 1901, 1906) observed a number of presenile and senile patients with focally accentuated neocortical atrophy and associated neuropsychological deficits. O. Binswanger (1894) and A. Alzheimer (1895, 1898, 1902, 1904) had described a variety of vascular brain changes associated with severe cognitive impairment that could be distinguished clinically and neuropathologically from progressive paralysis. The clinicopathologic paradigm led to the delineation of several new diseases. The exploration of progressive paralysis itself led beyond the realms of clinical and pathological Contributions of German Neuroscience 73 description, etiology, and therapy. The combination of more specific diagnostic methods and therapeutic success led to a steep decrease in the number of patients with progressive paralysis. During the same period old diseases were on their way up, and new diseases were born. Senile dementia (Altersblödsinn) was considered the most common mental disorder and gained increased attention (Alzheimer 1898). E. Redlich (1898) found extraneuronal plaques (miliary sclerosis) in patients with dementia. Blocq and Marinesco (1892) had observed similar plaques in patients with temporal lobe epilepsy. Beljahov (1889) had even seen plaques in senile dementia. Cortical atrophy and ventricular enlargement in senile dementia had been known for some time (Kraepelin 1899; Marce 1863). In the sixth edition of his textbook of Psychiatry, E. Kraepelin (1899) listed macroscopic brain atrophy, neuronal atrophy, and pigmentation as the typical postmortem findings in senile dementia, referring to Campbell’s study published in the Journal of Mental Science (1894, 638). Kraepelin mentioned that senile dementia usually begins between the ages of 65 and 75, ‘‘sometimes earlier (senium praecox)’’ (1899, 356). This senium praecox is nosologically unrelated to Dementia praecox and Dementia paralytica, which were considered in separate chapters. In the famous eighth edition of his textbook (1910), Kraepelin singles out a peculiar (eigentümlich) group of cases with severe neuronal changes. Clinically, these are characterized by ‘‘immensely severe mental disease with fuzzy (verwaschene) signs of an organic brain disease’’ (624). Kraepelin gives a vivid account of characteristic psychopathological and neurological findings and goes on to elaborate clinicopathologic correlations and differential diagnostic issues. Alzheimer disease (Alzheimersche Krankheit; p. 627) was characterized by severe dementia, profound aphasia, spasticity, and seizures; whereas presbyophrenia represented a simple deterioration of mental capacity (geistiger Besitzstand) without further physical and psychopathological disturbances. Of 183 patients who were between the ages of 65 and 80 and who had senile dementia, 23 percent were diagnosed as having presbyophrenia, 63 percent as having simple senile dementia (einfacher Altersblödsinn), 8 percent as having severe arteriosclerotic forms, and the rest as having senile paranoia (seniler Verfolgungswahn; p. 629). Kraepelin hypothesized that a neuronal degeneration with a deposition of pathological material was the anatomical correlate of presbyophrenia. On the other extreme, focal vascular change would lead to a mosaic of individual disturbances in the arteriosclerotic group of senile dementia. Kraepelin discussed the difficulties of drawing clear lines between (1) arteriosclerotic and primary [54.235.6.60] Project MUSE (2024-03-19 13:32 GMT) 74 Hans Förstl degenerative forms of senile dementia, clinically and neuropathologically ; (2) senile dementia—particularly presbyophrenia—and normal aging; and (3) presenile AD and senile dementia. Kraepelin concluded: ‘‘At present the clinical importance of Alzheimer ’s disease is still unclear. While the anatomical findings would suggest that it represents a particularly severe form of senile dementia, the fact that it may start in the 40s argues against that view. One would have to assume at least a senium praecox, if it was not perhaps a more or less age-independent disease process of its own’’ ( 1910, 627). The main arguments for a separate histological position of AD were (1) onset, (2) severity and type of...