Senescence, the Last Half of Life

by G. Stanley Hall

That organs that have reached full maturity and differentiation are stable and fixed in cell type and organization is false. Our organs are constantly in active regression, degeneration, and progression, and it is difficult to separate pathological from physiological changes. The pancreas is particularly in constant regression and progression. Thus it is peculiarly unstable and the limit of normality in its variations cannot be determined. Senescence is accompanied by multiple degenerative changes in many other organs and tissues, and associated with these are various benign and malignant tumors that seem to result from degenerative changes. Thus Oertel’s idea of endless proliferation as a result of differentiation is not an idle speculation but rests upon an anatomical and experimental basis.

A. S. Warthin[149] says that syphilitic cases are generally regarded as cured if the Wassermann reaction is negative but there are very many cases that this escapes. It is commoner than is supposed, the usual estimates being that from 5 per cent to 15 per cent of deaths are due to it, but this writer for America and Osler for Great Britain, place it at 30 per cent. “Syphilis is the leading infection and the chief cause of death, particularly in males between 40 and 60, and in the great majority of cases its symptoms are myocardial, vascular, renal, or hepatic, and this is often not recognized as a remote result.” The author has never seen a marked case of syphilis cured. Most die as a result of mild inflammatory processes of the viscera and blood vessels rather than from paresis or tabes. It is progressive and marks the individual as damaged goods. Even immunity is bought at a price. All the organs must be examined before it is pronounced certainly absent. It is a spirochete-carrier. It tends to become mild but at any time the partnership between the spirochete and the body may be disturbed and the tissues susceptible to the violence of the spirochete may be increased so that the disease again appears above the clinical horizon. Chronic myocarditis is the most common form of death.

W. Spielmeyer[150] says that in the last decade the clinicians and pathological anatomists have discussed old age more than in preceding decades. We know that organs are used up and that their substance is not fully replaced. The functionally exciting parenchyma is injured by its own function and in this metabolism the quality and sometimes the volume of the organ is reduced. Thus old age is a function of the work of the organism and it seems to be an intrinsic quality of cells to use themselves up. Many do not regard age as a normal physiological process but with Metchnikoff think it is due to injurious substances, that is, endogenous toxins that are more important than the exogenous factors, so that blood vessels, glands, and muscle and ganglia cells degenerate. But the cortical cells, as the most sensitive of the organism, are more often injured. Metchnikoff thinks that the higher elements of the tissues are in conflict with the lower and are overcome by them, the phagocytes being left masters of the field.

Few, however, hold this view. Ribbert, Naunyn, Hansemann, and Nothnagel think that outer and inner injuries should have precedence in accounting for old age. But without these coöperative factors there is a physiological determinant of the organism and its parts to be used up and they become senile and lapse by physiological processes, while Naunyn thinks that it is perhaps a general law that every organ fulfills its functional task only by impairment of its complete organic integrity. This using up of an organism by its own work occurs first in the brain and the central nervous system. There is a general decline in weight, even in the fourth or third decennium, which is accelerated in the seventies and may reach one hundred grams (Naunyn) and, in pathological states, still more. It is, therefore, of great interest for the relation of function and the use-up of organs that brain atrophy is not usually uniform or diffuse but that there is often a difference between the right and left hemispheres in the diminution of their volume. The left hemisphere is more used and usually more atrophied than the right. The left convolutions, therefore, suffer most reduction.

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.

With the great recent progress of anatomy we are just at the beginning here, the chief result so far being the possibility of distinguishing senile involution and its morbid traits with a view to eventually being able to make an anatomical differential diagnosis, such as we must do to really get at the root of the problem of senile dementia. From this point of view other processes can readily be derived, and some of them histologically, like regression. The anatomical investigation stands in temporal relations with the idea of senile dementia and it must be defined or widened enough to do this. Perhaps we shall be able to have a good anatomical picture of senile dementia beginning with the fifth and sixth decennium and even to explain atypical forms and show their relation with the central system.

Here, then, the author, starting from an anatomical basis, begins with a study of forms that are atypical in localization, intensity, or temporal onset. Then he can discuss the mental diseases that are based on sclerosis. So he first discusses briefly those psychoses that rest upon clearly recognizable but not yet very distinctly determined brain troubles that deviate from the ordinary senile processes and those, which so far as we can now see, are really sclerotic. Then the long series of psychoses, the anatomical substratum of which we do not yet know, and the functional processes of this age can be discussed. In doing this, more than in the case of many organic processes, we shall find a great difficulty in proving for such diseases their specific senile or climacteric character. We shall constantly face the objection that we have here to do only with mental diseases that usually come in other ages and only have peculiar traits on account of the age of the patient, as is the case with many depressive and paranoiac symptom-complexes of regression that resemble those of age.

Thus the distinction of regressive psychoses from senile changes, this author thinks, cannot be carried through by grouping them in the decennia in which they arise. It would be better to distinguish them as progressive and incurable, or otherwise, but this could be done only with further distinction of our anatomical and clinical data and we shall perhaps still lack that for a long time.