Many problems concerning Alzheimer's disease and Pick's disease are still awaiting clarification. In this country Henderson was the first to draw attention to the considerable importance of Alzheimer's disease in clinical psychiatry. Valuable work has been contributed by various writers in recent years (Grunthal, 1936; Critchley, 1929, 1930, 1931, 1938; Schottky, 1932; Thorpe, 1932; Rothschild, 1934; Malamud, Lowenberg and co-workers, 1929; Mayer-Gross, 1938; Kasanin and Crank, 1933; Jervis and Soltz, 1936; McMenemy, a.o., 1939). While Pick's disease has retained its position as a clinical entity based mainly on the characteristic anatomical picture, the position of Alzheimer's disease in the system of psychiatry has become more complicated; for instance atypical cases have been described presenting the anatomical characters of Alzheimer's disease, though not fitting into the original clinical conception of that disease. Lowenberg and his co-workers (1929) are inclined to regard Alzheimer's disease as a syndrome rather than a clinical entity. Many contributors have directed their main interest to the pathological changes. The knowledge of the symptomatology of those conditions is still incomplete. Further intensive study may enable us not only to base the diagnosis and differential diagnosis of Alzheimer's disease and Pick's disease on more solid clinical knowledge than hitherto, but also to recognize the early stages of those diseases before advancing cerebral degeneration effaces their characteristic clinical features. Unfortunately, most of the cases come under the observation of the psychiatrist only in the later stages of their illness, and it seems that the comparatively small proportion of the mental hospital population they represent does not reflect the incidence of those diseases. It is very likely that many patients die from intercurrent illnesses before their mental condition is recognized or sufficiently advanced to make admission to a mental hospital necessary. The differential diagnosis of those conditions offers considerable difficulties which often may prove insuperable. Alzheimer's disease and Pick's disease have to be distinguished not only from each other but from conditions of vascular origin, from senile dementia and various atypical conditions which occur at the same age period during which Alzheimer's disease and Pick's disease usually develop. Only careful collection and analysis of clinical observations and their scrutiny by pathological investigations can increase our still limited knowledge in this important field of psychiatry.
Structures of filaments from Pick’s disease reveal a novel tau protein fold
