ABSTRACT
In this Introduction no mention has been made as yet of the problems connected with diagnosis. Since this study—so far as it is psychiatrical—has not the purpose of text-book discussion in view, many important nosological points will be omitted. Only such psychiatrical features of manic-depressive insanity will be included as have psychological interest and pertinence, moreover, for our special theme. Among these, however, is the problem of differentiation of dementia praecox from the psychoses, that are the object of our intensive research. To confuse a typical case of dementia praecox with a typical mania or depression would be a psychiatrical crime. But both are constitutional psychoses, both seem to arise on analogous backgrounds, so it is not surprising that many cases appear which resemble both diseases. These furnish, probably, the largest group of diagnostic puzzles in institutional practice. In New York State official cognizance has been granted to this difficulty by the establishment in the lists of psychoses of the divisions “Allied to Manic-Depressive Insanity” and “Allied to Dementia Praecox”. These diagnoses have been copied elsewhere. If the essence of either dementia praecox or mania-depressive insanity lies in a peculiar reaction type, the analysis of the symptom picture, betraying the specific reaction type, should facilitate diagnosis. It will appear that some progress has been made along this line.
