"The very great majority of cases [of dementia præcox] begin in the second or third decade; 57 per cent, of the cases made use of in the clinical description began before the twenty-fifth year. This great predisposition of youth led Hecker to the name hebephrenia, "insanity of youth," for the group delimited by him; Clouston also, who spoke of an " adolescent insanity," had evidently before everything dementia praecox in view. ... Hecker was even inclined to regard the issue of his hebephrenia just as an arrest of the whole psychic life on the developmental stage of the years of puberty. In fact, we find in silly dementia at least many features which are well known to us from the years of healthy development. Among these there is the tendency to
unsuitable reading, the naive occupation of the mind with the "highest problems," the crude "readiness" of judgment, the pleasure in catch words and sounding phrases, also sudden changes of mood, depression and unrestrained merriment, occasional irritability and impulsiveness of action. Further the desultoriness of the train of thought, the half-swaggering, boastful, half-embarrassed, shy behaviour, the foolish laughing, the unsuitable jokes, the affected speech,
the sought-out coarseness and the violent witticisms are phenomena which in healthy individuals, as in the patients, indicate that slight inward excitement which usually accompanies the changes of sexual development." From Kraepelin, EmilDementia praecox and paraphrenia, Chapter IX "Frequency and Causes", Chicago Medical Book. Co., (Text), 1919