Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/106

 9G INSANITY eminently unsatisfactory, founded as they are on common observation, broad generalizations, and very imperfect statistics. As they are for the most part negative in result, at the best almost entirely irrelevant to the present purpose, it is proposed merely to shortly summarize the general outcome of what has been arrived at by those authorities who have sought to assess the value to be attached to the influence exercised by such factors, without entering in any detail on the theories involved. (1) Civilization. Although insanity is by no means unknown amongst savage races, there can be no reasonable doubt that it is much more frequently developed in civilized communities ; also that, as the former come under the influence of civilization, the percentage of lunacy is increased. This is in consonance with the observation of disease of whatever nature, and is dependent in the case of insanity on the wear and tear of nerve tissue involved in the struggle for existence, the physically depressing effects of pauperism, and on the abuse of alcoholic stimulants ; each of which morbid factors falls to be considered separately as a proximate cause. (2) Nationality. In the face of the imperfect social statistics afforded by most European and American nations, and in their total absence or inacces sibility amongst the rest of mankind, it is impossible to adduce any trustworthy statement under this head. (3) Occupation. There is nothing to prove that insanity is in any way connected with the prosecution of any trade or profession per se. Even if statistics existed (which they do not) showing the proportion of lunatics belonging to different occupations to the 1000 of the population, it is obvious that no accurate deduction quoad the influence of occupation could be drawn. (4) Udiication. There is no evidence to show that education has any influence over either the production or the prevention of insanity. The general result of discussions on the above subjects has been the production of a series of arithmetical statements, which have either a misleading bearing or no bearing at all on the question. In the study of insanity statistics are of slight value from the scientific point of view, and are only valuable in its financial aspects. Of much greater importance is the question of hereditary predisposition to nervous disease. There is a general and warrantable position taken up by the medical profession, founded on the observation of ages, that a constitutional condition may be generated in a family, which, although it may never manifest itself in a concrete form of disease, may materially influence development, or may make itself felt in a more subtle manner by a mere tendency to degenerative changes. In this wise hereditary predisposi tion may be regarded as a common factor in all insanities in the congenital class as an arrester of brain develop ment, in the acquired as the producer of the nervous diathesis. How the constitutional condition is generated, and in what its pathological nature consists, is beyond the ken of science ; it may in fact be freely admitted that the proof of its existence hangs more on popular observation than on scientific evidence. The observation is not con fined to the nervous system ; it extends itself to others, as is shown by hereditary predisposition to gout, consumption, cancer, and other diseases. It has been strongly asserted that consanguineous marriage is a prolific source of nervous instability. There is considerable diversity of opinion on this subject; the general outcome of the investigations of many careful inquirers appears to be that the offspring of healthy cousins of a healthy stock is not more liable to nervous disease than that of unrelated parents, but that where there is a family history of diathesis of any kind there is a strong tendency in the children of cousins to degeneration, not only in the direction of the original diathesis, but also towards instability of the nervous system. 1 The objection to the marriage of blood relations does not rise from the bare fact of their relationship, but has its ground in the fear of their having similar vitiations in their constitution, which, in their children, are prone to become intensified. There is sufficient evidence adducible 1 to prove that close breeding is productive of degeneration : and when the multiform functions of the nervous system are taken into account, it may almost be assumed not only that it suffers concomitantly with other organs, but that it may also be the first to suffer independently. Of the other causes affecting the parents which appear to have an influence in engendering a predisposition to insanity in the offspring, the abuse of alcoholic stimulants and opiates, over-exertion of the mental faculties, ad vanced age, and weak health may be cited. Great stress has been laid on the influence exercised by the first of these conditions, and many extreme statements have been made regarding it. Such must be accepted with reserve, for, although there is reason for attaching considerable weight to the history of ancestral intemperance as a probable causating influence, it has been generally assumed as the proved cause by those who have treated of the subject, without reference to other agencies which may have acted in common with it, or quite independently of it. The question has not as yet been fairly worked out. However unsatisfactory from a scientific point of view it may appear, the general statement must stand that whatever tends to lower the nervous energy of a parent may modify the development of the progeny. It is merely a matter of probabilities in a given case. Constitutional tendency to nervous instability onco established in a family may make itself felt in various directions, epilepsy, hysteria, hypochondriasis, neuralgia, certain forms of paralysis, insanity, eccentricity. It is asserted that exceptional genius in an individual member is a phenomenal indication. Confined to the question of insanity, this morbid inherit ance may manifest itself in two directions, in defective brain organization manifest from birth, or from the age at which its faculties are potential, i.e., congenital insanity; or in the neurotic diathesis, which may be present in a brain to all appearance congenitally perfect, and may present itself merely by a tendency to break down under circumstances which would not affect a person of originally healthy constitution. In systematic works and in asylum reports, it has been too much the fashion t:&amp;gt; accept the evidence of the existence of insanity in a relative as a proof of hereditary predisposi tion in a given case. In estimating the value to be attached to such histories, two things must be taken into account, first, the amount and quality of proved ancestral nervous disease, and, secondly, the period of life at which it appeared in the alleged insane ancestor. Take, for instance, the case of a lunatic whose father or mother is reported to have died insane ; this may be true in fact, but may still have no bearing on the causation of the patient s insanity; for the parent may have been the subject of mental disease at a period subsequent to the birth of the child, he may have drunk himself into alcoholic mania late in life, or disease of the cerebral arteries in old age may have produced senile insanity. It is difficult to limit the remote- 1 See Report of Committee appointed by New York State Medical Society, in American Journal, of Insanity, 1870 ; G. H. Darwin, Statistical Society s Journal, Jiine 1875; Dr Langdon Down, &quot;On Marriages of Consanguinity,&quot; London Hospital Clinical Lectures and Reports, 1866 ; Dr Arthur Mitchell, &quot; On Consanguineous Marriages,&quot; in Edin. Med. Journ., 1865 ; Maudsley, &quot;On Hereditary Tendency,&quot; Journal of Mental Science, Jan. 1863 and Jan. 1864 ; Troiisseau, Clinique Medicate de l H6tel de Dicude Paris, 1868, vol. ii. pp. 129- 137 ; Alfred Henry Huth, The Marriage of Near Kin, 1875.