Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/112

 102 INSANITY more slowly produced, the nervous system is first depressed. And hero the position becomes somewhat complicated ; for not only is, under such circumstances, the relative amount of tho blood constituents different from tho normal standard, but its corpuscular elements change in quality ; they acquire a degree of viscidity which tends to cause tho red corpuscles to coalesce and hang together, and the white to lag and wander into surrounding tissues; and further, this unphysiological behaviour of the corpuscles is apt to become aggravated in regions whose nervous energy is depressed. Anfemia thus acts and reacts in procuring a condition of stasis. 6. The effects of evolutional periods concurrently affect ing tho brain : puberty, adolescence, utero-gestation, the climacteric period, and old age. &quot; Although from the time when the human being comes into the world to the final cessation of his corporeal existence the various functional operations of organic life are carried on with ceaseless activity, whilst those of animal life are only suspended by the intervals of repose which are needed for the renovation of their organs, yet there are very marked differences, not only in the degree of their united activity, but also in the relative degrees of energy which they severally manifest at different epochs&quot; (Carpenter s Principles of Human Physiology, chap, xviii.). These differences in degree imply physiological modifications of nutrition, and the observation of ages has caused it to be accepted as a fact in the etiology of disease that numerous and various degenerations occur contemporaneously with such modifications, more especially in the subjects of diathetic conditions. The development of phthisis during adolescence, and of cancer amongst persons at the climacteric period, maybe cited as instances. It may be freely admitted that the nexus between the physiological and the pathological position is, as regards certain of the periods, obscure, and that it is dependent more on induction than on demonstration ; but it may be pleaded that it is not more obscure in respect of insanity than of other diseases. The pathological difficulty obtains mostly in the relation of tho earlier evolutional periods, puberty and adolescence, to insanity ; in the others a physiologico-pathological nexus may be traced ; but in regard to tho former there is nothing to take hold of except the purely physiological process of development of the sexual function, the expansion of the intellectual powers, and rapid increase of the bulk of the body. Although in thoroughly stable subjects due provision is made for these evolutional processes, it is not difficult to conceive that in the nervously unstable a considerable risk is run by the brain in consequence of the strain laid on it. Other adju vant influences may be at work tending to excite the system which will be spoken of when the insanity occurring at these periods is described. Between the adolescent and climacteric periods the constitution of the nervous, as of the other systems, becomes established, and disturbance is not liable to occur, except from some accidental circumstance apart from evolution. In the most healthily constituted individuals the &quot;change of life&quot; expresses itself by. some loss of vigour. The nourishing (trophesial) function becomes less active, and either various degrees of wasting occur, or there is a tendency towards restitution in bulk of tissues by a less highly organized material. The most important instance of the latter tendency is fatty degenera tion of muscle, to which the muscle of tho arterial system is very liable. In the mass of mankind those changes assume no pathological importance : the man or woman of middle life passes into advanced age without serious con stitutional disturbance ; on the other hand, there may be a break down of the system due to climacteric disease of special organs, as, for instance, fatty degeneration of the heart. In all probability the insanity of the climacteric period may be referred to two pathological conditions : it may depend on structural changes in the brain due to fatty degeneration of its arteries and cells, or it may be a secondary result of general systemic disturbance, due to cessation of menstruation in the female, and, possibly, to some analogous modification of the sexual function in men. The senile period brings with it further reduction of formative activity ; all the tissues waste, and are liable to fatty and calcareous degeneration. Here again the arteries of the brain are very generally implicated : atheroma in some degree is almost always present, but is by no means always followed by insanity. Whewell retained his faculties to the last, notwithstanding that his cerebral arteries were much diseased. Still this condition must be taken into account in studying the causation of senile insanity, as it necessarily implicates the nutrition of the brain. It must assist in preventing recuperation of the cells ; it may in cer tain instances diminish suddenly the blood supply to a par ticular area; but the stronger probability is that senile mental decay lies at the door of senile degeneration of the cells. The various and profound modifications of the system which attend the periods of utero-gestation, pregnancy, and child-bearing do not leave the nervous centres unaffected. Most women are liable to slight changes of disposition and temper, morbid longings, strange likes and dislikes during pregnancy, more especially during the earlier months ; but these are universally accepted as accompaniments of the condition not involving any doubt as to sanity. But there are various factors at work in the system during pregnancy which have grave influence on the nervous system, more especially in those hereditarily predisposed, and in those gravid for the first time. There is modification of direction of the blood towards a new focus, and its quality is changed, as is shown by an increase of fibrin and water and a decrease of albumen. How much these 1 changes structurally affect the encephalon may be deduced from the fact of the presence of bony plates (osteophyte) on the surface of the dura mater, and the inner table of the skull, and how much functionally, by constant congestions and flushings. To such physical influences are superadded the discomfort and uneasiness of the situation, mental anxiety and anticipation of danger, and in the unmarried the horror of disgrace. In the puerperal (recently delivered) woman there are to be taken into pathological account the various depressing influences of child-bed, its various accidents reducing vitality, the sudden return to ordinary physio logical conditions, the cessation of the occasional physio logical condition, the rapid call for a new focus of nutrition, the translation as it were of the blood supply from the uterus to the mammse, all physical influences liable to affect the brain. These influences may act independently of moral shock; but, where this is coincident, there is a condition of the nervous system unprepared to resist, or, it may rather be said, prepared to succumb. 7. Among the toxic agents which affect the brain, alcohol holds the foremost place. On the action of this poison the article DEUXKENNESS supplies full information. Consider able difficulty exists as to the estimation of the importance to be attached to alcohol in the production of brain disease from the fact that excess in the use of stimulants is very frequently a symptom of incipient insanity, and that the symptom is often mistaken for the cause. The habitual use of opium and Indian hemp (Cannabis indica), which first stimulate and then paralyse the action of the cerebral cells, is a frequent cause of lesion. Difficulties may arise in individual cases in establishing a theory of causation from the presence of what are generally spoken of in systematic works on insanity as &quot; mixed&quot; causes, i.e., the presence of two morbid factors in one individual. So long as these consist in variety in