ABSTRACT
The diagnoses by which psychiatry tries to find a classification system similar to nosological systems of other medical branches are continually changing. The psychiatric diagnostic schemes of the past 150 years have seldom remained valid for more than a few decades. Nowhere are the difficulties of diagnosis greater and the basic doubts respecting psychiatric nosology more evident than in dealing with the mental disorders of old age. The survey of old-age mental disorders which follows cannot go into detail and therefore can indicate only the diagnostic difficulties and the nosological considerations inspired by them. Endogenous psychoses that arose during earlier years will certainly not become somatically based psychoses when organic changes occur in old age. In dealing with illnesses that occurred in old age and where endogenous and organic features intersect, it is often possible to decide whether we are confronted with an accidental combination, with an endogenous psychosis caused by organic changes, or with an atypical, somatically based psychosis.
