OLD AGE. - Biologists and physicians today tend to differentiate the concept of senescence from that of senility or old age. Thus, according to Pende, by the first term should be understood the process of functional decline and structural deformation of the organism that naturally affects all its parts at various times and degrees at a certain epoch of life; whereas by senility or old age is understood the vital phase in which the phenomena of senescence have already established themselves in evident and definitive form.
According to biologists, senescence (v.) is a characteristic and essential property of life (v. BIOLOGICAL CYCLES), common to all complex organisms. Together with growth and death (v.) it forms part of the most distinctly specific properties of organized living substance, quite as essential as metabolism, to which moreover they are intimately linked. The ever deeper knowledge of the life of unicellular elements, the understanding of the transmission of life through the fertilized egg, and Carrel's experiments (v.), who succeeded in keeping a fragment of embryonic myocardium alive for 28 years by cultivating it under particular environmental conditions, have increasingly confirmed the hypothesis that the phenomenon of senescence and death should not be considered as specific to living matter, but rather as a particular appanage of the process of organization by which the higher individual is constituted.
Senility was once considered a directly pathological phenomenon (senectus ipsa morbus); today, instead, it is considered a physiological event, proper to living organisms, in that, although it is aggravated and hastened by the after-effects of previous illnesses and by innumerable other physical and psychic causes of decay that accompany human existence, it begins at a given epoch of life (60-70 years for men, 55-65 for women) independently of any concomitant morbid factor, with a set of phenomena of involution and degeneration that affect the whole organism, profoundly modifying it both from the morphological and from the biochemical and physiological point of view. Pende maintains that senility is characterized by multiple deficiency phenomena: circulatory stasis; toxic stasis in the interstitial lacunar system of the organs; gastro-intestinal stasis with autointoxication of the organism from ptomaines, from products of incomplete digestion of albumins, from toxins from the intestinal bacterial flora; altered neurovegetative (v. NEUROVEGETATIVE SYSTEM) and metabolic (v. METABOLISM) balance with a tendency to hyperfunction of the sympathetic system, to acidosis, to the accumulation in the blood of cholesterol, glucose, nitrogen, uric acid, and a decrease in calcium; altered function of the endocrine glands (v.), of the liver, of the kidney; and others still.
These phenomena are due to, or are accompanied by, alteration of certain tissues, systems, and apparatuses, which are struck earlier than others by the involutional process of senescence. Thus the atrophy of elastic tissue, whether of the skin (wrinkles of the face), or of the vessels (arteriosclerosis), or of the lungs (senile emphysema), or of the intestinal and abdominal walls (protrusion of the belly); the hypofunction of the reticulo-endothelial system, regulator of tropism, of vitality, of the organism's powers of defense against external agents, is responsible for the senescence of the more specifically differentiated tissues of the organs; the entire apparatus of the endocrine glands is shaken in its relations of hormonal correlation with phenomena of hypofunction (insular gland, thymus, gonads) or of hyperfunction (adrenals, especially cortical, basophilic portion of the hypophysis, thyroid) or variously alternating (hyper-or hypo-parathyroidism).
According to Viale, the physiological and biochemical phenomena that characterize senility are principally: the quantitative diminution of functions and the lesser capacity for adaptability to environmental variations.
Various hypotheses have been formulated to explain the onset of old age. Some consider as the basis of the process of senescence a toxicosis of intestinal origin (Metchnikoff) or extraintestinal origin (Jeckeli-Ewald); others an endocrine disturbance, hypophyseal, adrenal, or complex (Simmonds, Lorand, Gley); others a more or less complex metabolic disturbance (Bornstein, Pende); others the physico-chemical differentiation of tissues through dehydration and precipitation of protoplasmic colloids; others still, such as Carrel's suggestive one, consider as the direct cause of senility an alteration of the humoral environment of the cells, which would be deprived of the "quid" necessary for normal growth (Carrel's "trefones").
On the possibility of prolonging life and rendering old age less burdensome, Legrand affirms that "il n'y a pour vivre vieux, ni règle, ni méthode, ni hygiène spéciale." Hufeland, however, in 1796 published the Microbiotica, or the art of prolonging life, and Lorand in his book Rejuvenation (Turin 1926) listed 10 bad habits as causes of premature senescence and death (alcohol, overnutrition, tobacco, sexual excess, filth, ambition, avarice, anger, vanity, practices tending to avoid offspring). The importance of these and other factors, such as idleness, insomnia, constipation, is undoubted; but in the establishment of old age at a more or less early epoch of life, extra-individual factors also play a part, such as heredity, race, climate, temperature, so that it may be affirmed that every individual ages in his own way, presenting at a given epoch of life this or that particular organ more predisposed to senile involution.
According to Marinesco, "old age, like death, is fatally inscribed in the vital curve of the colloids and implicitly in the evolution of the cells. Life and death are natural and necessary phenomena, and the hypotheses of authors who see in the phenomena of senescence a remediable accident are in discordance with the universal law that governs the life of the colloids" (jubilee volume in honor of L. Bianchi, Catania 1913). Many authors, however, in all countries have tackled the problem of the possibility of a rejuvenation of the individual, resolving it in a manner sometimes suggestive even if, at least for now, only transitory.
The first to awaken interest in the problem of rejuvenation, as a return of the conditions of body and spirit of the old toward youth, was Brown-Séquard, who thought of injecting subcutaneously into the old and the sick the juice extracted from the testicles of animals, having first successfully tested it on himself, by then 72 years old. Since then numerous other researchers have occupied themselves with the same problem, resolving it in various ways: Steinach and Lichyeenstern by ligation of the vas deferens, Döppler by periarterial sympathectomy, Zucchi with a diathermic procedure, etc., down to our own days, which have seen strenuous defenders and bitter opponents of the method proposed by Voronoff and developed by Dartigues, founded on the transplantation of a monkey's testicle into man. It is also worth recalling two other recent methods: that of Jawerski, based on the intravenous introduction of youthful blood, and that of Cavazzi, who advocates the injection of venous testicular blood drawn from young and healthy animals.
At the present moment, however, no proposed method has given constant and definitive results. According to Marinesco, even if there is an undoubted relationship between life and the sexual glands, one absolutely cannot say that old age depends on the state of these glands. For the author, the decay of the gonads is not the cause, but rather one of the signs of old age.
The impossibility of obtaining a rejuvenation of the individual through opotherapeutic and hormonal treatments is also believed by Kotsawski, who maintains (Riv. Biol., 12 [1930], p. 40) that to rejuvenate the organism there is nothing else to do but replace the injured and diseased organs with healthier ones.
According to Pende, prolonging human life — active and without ailments, that is, adding life to years and not years to life — by at least a quarter of a century, is scientifically possible, but it is a problem of constitutional, individual, biotypological medicine, whose resolution requires hygiene and a complex and multiple drug therapy and opotherapy. In relation to the increased average lifespan (65-67 years) and the growing percentage of the elderly in the population, medicine currently takes an ever greater interest in the problem of old age and its treatment, giving rise to the growing development of two new branches of it: "gerontology" and "gerontology."