Certain poisons exert destructive action upon the nervous system and upon the brain. These include morphine and cocaine, the habitual use of which leads to the terrible conditions known as morphinism and cocainism. Syphilis is, however, of much greater practical importance. This disease, which may be inherited or acquired, is one of the chief causes of the much dreaded and very frequent form of insanity known as general paresis. See BRAIN, SOFTENING OF.
Alcohol is the most reliable contributor to the insane asylums, for not only is the inebriate rendered insane by it, but its curse is transmitted to his offspring. No disease (and inebriety must be thus designated) exerts an equally deleterious influence upon the succeeding generations. At least one-third of all insane and idiotic persons have become so because of the abuse of alcohol, either on the part of themselves or on that of their parents.
Mental disturbances may arise also in connection with other affections of the brain and of the nervous system. Attention may be directed to the deteriorations following cerebral apoplexy, injuries to the skull, tumours of the brain, and epilepsy ; as well as to those resulting from hysteria and " nervousness," which might be designated as affections intermediate between nervous and cerebral diseases.
That mental are on the increase is frequently being asserted, and this is ascribed to the nerve-destroying life of modern times. The truth of this contention, however, has by no means been proved. It is true that there are more insane asylums to-day than there were formerly, but this increase may be readily explained by the fact that very many patients are now admitted to insane asylums Nvho formerly remained with their families, or ‘vho were cared for in poorhouses or in hospitals. In considering this question, the modern and more exact methods of census-taking must also be taken into account ; nor must the fact be ignored that the inmates of the asylums attain a higher age nowadays as a result of better treatment and care. Harmful influences unquestionably result from the greater nervous strain demanded by modern conditions—the general competition, the increasingly difficult struggle for existence, the pursuit of earthly blessings and sensual pleasures, etc.—but these are fully counterbalanced by the vastly better material conditions of the present day. To prove this conten tion, it is sufficient to compare our dwellings, dress, food, water-supply, the methods of fighting epidemics, etc., with the conditions prevailing during the eighteenth century.
The manifestations of mental disturbances, as well as their courses, are so varied that it is extremely difficult to define any one accurately. Further more, it is difficult to say when it is justifiable to speak of mental diseases. Laymen look upon these matters in a manner which is entirely unwarranted by the actual conditions. They believe a mental affection to be characterised by irrational talk and foolish acts. But when questioned as to the boundary line between " rational " and " irrational," they are at a loss to explain. As in the colours of the rainbow no one is able to determine Nr here red passes into yellow and where yellow into green, so it is impossible also for the most skilful alienist to state the exact point of demarcation between mental sound ness and mental unsoundness. As the bright day gradually passes through dusk into dark night, so do many steps lead slowly from mental lucidity down to the deepest darkness of mental obscurity. These transitional stages arc designated by the alienists as mental inferiority or degeneration, in contrast to mental disease. How wide the variations may be can readily be perceived by calling to mind the numerous odd characters met with in every walk of life. The eccentrics, the problematists, the unpractical dreamers, the visionaries, the congenitally weak-minded simpletons who are on the boundary-line between normal stupidity and morbid imbecility, and, finally, the habitual criminals, vagabonds, and tramps—all of these may be regarded as being more or less abnormal, although not necessarily mentally diseased in the true acceptation of the term.
Owing to their peculiarities, these mentally degenerated persons are very liable to come in conflict with the law ; and, since mentally unsound individuals must be regarded as irresponsible, and dare not be punished, the vast. importance, but also the difficulty, of correctly estimating their mental condition becomes evident. The alienist has merely a choice between two decisions : mentally responsible, or not. The law makes no provision for intermediate conditions, such as diminished soundness of mind. This readily explains the frequent differences of opinion between alienists and laymen, especially jurists. These divergencies are due to the fact that the legal definitions are not adapted to actual conditions, but are based upon the erroneous contention that it is possible in every instance to distinguish precisely between mental disease and mental soundness.