Among the earliest and most uniform changes due to age is the regressive transformation of the blood vessels as in sclerosis. As the central tissues suffer from a using up of their nervous substance, the central vessels are soon involved. Till lately we have assumed that these disease processes in senium were a result and expression of the primary affections of the blood vessels in these organs. But it now appears that as in other organs, for example, the kidneys, grave age changes can occur while blood vessels are intact. So in the central organ grave independent age changes can occur without being caused by the blood vessels. To be sure, they often concur for the simple reason that the nervous system, like that of the vessels, is found affected oftenest and earliest in old age. But the assumption of a dependence of central nervous degeneration was an erroneous conclusion from the observation that by these frequent degenerative processes in the walls of the vessels there were, at the same time, phenomena of using up of nerve substance. “The changes of both organs can, despite their frequent combination, be the independent expression of age and quite independent one from the other.” Every study of the psychosis of regression and age must start from this fact and we must seek to distinguish the forms of weakness of old age due to central tissues from those that have their cause in the primary weakness of the blood vessels. For sclerotic senile dementia anatomy has already more or less basis. For the various forms of brain sclerosis it is now possible to propose an anatomical diagnosis, although it is impossible to have a very definite clinical picture of what takes place. Outside these two chief groups of organically conditioned psychosis and degeneration there are many processes not yet certainly determined anatomically. These belong neither to sclerotic brain disease nor to proper senile dementia. They differ also in their general aspects from the average case of the imbecility of old age, and if they are classified with it, this rests only on superficial grounds and it is the problem of pathological anatomy to help clear up this clinical-psychological question. It is a little here as with innate and childish mental weakness, which we anatomically distinguish as idiocy and imbecility with partial success, just as we are trying to distinguish the psychosis of old age to make it conform to anatomical principles.