EPIDEMIC MENTAL DISEASES. When we consider how ordinary and normal thoughts and emotions spread from one man to many, and sway multitudes to the same views and actions, it is no longer a mystery that morbid conditions of the mind should become at times.ndlesS epui7emue than physical tiliSeases. SuCh, af least, is the fact. A mental disorder may spread from man to man, and may involve whole nations. It depends for its propagation, like an epidemic disease, first upon external circumstances, and secondly, upon the peculiar condition or constitution of the individuals affected. Like the bodily affection, the causes which provoke the insanity and the tendency to be affected may have been in process of development for years. Both attack the weak rather than the strong; both exist for a season, and disappear. In the case of the mental malady, the external influences—those which constitute the moral atmosphere—are ignorance or imperfect knowledge, the power of one mind over another, the influence of language, the diffusion of particular opinions, the tendency to imitate. It is probable, however, that physical causes exercise an important influence in the production of such general mental conditions. In 1842 and 1844, there occurred in Germany and France, among the military, epidemics of meningitis with delirium, or inflammation of the membranes of the brain, when no moral factors were at work, but when diet, tem perature, etc., were. But even where the origin cannot be so distinctly traced, the co-oper ation of external as well as psychical agents may be legitimately predicated. It would accordingly be illogical to limit the production of the dancing mania (q.v.), which occa sionally, during several centuries, swept over Europe, to the reaction succeeding the dread of the end of the world, which had previously prevailed epidemically. An exam ination of about a hundred manifestations such as that alluded to, collected from various sources, demonstrates that not merely the intoxication of joy, but the most absurd forms of belief—that dreams, delusions, superstitions, corruptions_ of language, all instincts and passions, even movements and cries, may assume the forms, and, to a certain extent, may follow the laws of epidemic diseases. In far-distant ages, there are records of a
histrionic plague, when, after a summer of intense heat, all conceived themselves players, and traversed the streets, and sunk and died, repeating verses, and exhibiting extrava gant gesticulations; of whole communities being stricken with nightmare, which was so general as to be supposed and called contagious. There have been epidemics of homicidal and suicidal mania. In one age, hundreds are found possessed by Satan; in another, larger numbers converted into wolves; and in recent times, the leaping ague of Forfarshire, and outbursts of pyromania in various places, remind us that there may be still in the constitution of the human mind, and in the education and the habits of life prevailing, elements capable of realizing the catastrophe suggested by bishop Butler's question: What is to prevent a whole nation becoming mad? The instances of epidemic mental disease recorded in the following table, have been selected from a vast number of others, with a view of showing not the frequency or extent of such affection, but the range of the phenomenon through the powers and propensities of our nature.
There appears to be no guarantee that the present and future generation shall be exempted from similar visitations, except in the universal diffusion of knowledge and sound thinking, for it is invariably in the darkness of ignorance or in the twilight of imperfect knowledge that the moral plague comes.—Hecker's Epidemics of the _Middle Ages; Calmiel, De la Folie consider& sous le Point de Veue Pathologigue, P hilosophigue, Ilistorigue et Judickcire, depuis la Renaissance des Sciences en Europe jusqu'au dixneurieme Siecle, etc.; and Psychological Journal, passim.