Invented by Beard of America in the “sixties” to describe and to include a class of nervous affections more common in America than elsewhere, the term “neurasthenia” has been used with great elasticity since then to cover a multitude of obscure nervous affections of the most varied and opposing characters, to the great confusion of exact diagnosis and of scientific treatment. A process of elimination has, however, been going on during the past decade and much has been done to clear up and to define more precisely the essential characters of neurasthenia. In the Boston Medical and Surgical Journal of March 31st Professor Charles Dana deals with the important differential characters of this condition. While neurasthenia is, says Professor Dana, a psychosis or morbid condition of the cerebral nervous system it is different from a large number of psychical states which, though not acute or severe enough to constitute insanity, show a definite kinship to insanity. These cases come to the general practitioner or to the neurologist by whom they are put down commonly as some form of neurasthenia, hysteria, or “degeneration”. “It is my contention,” adds Professor Dana, “that a large number of these so-called neurasthenics and all the hysterics should be classed as prodromal stages or abortive types – a shadowy imitation – of the greater psychosis insanity. For in these cases it is the morbid mind which dominates the situation, not a weak eye-muscle, a poor stomach, a heavy womb, uric acid, arterio-sclerosis, or even an exhausted motor nerve cell.” The psychical centres of the brain are the primary seat of the disorder, but the body may also be at fault. Many of these neurasthenic conditions are understudies as it were of the graver forms of mental aberration. There are, broadly speaking, says Professor Dana, five classes of insanity which represent varying degrees of departure from mental health and stability of brain (excluding idiocy, imbecility, and the organic dementia of syphilis, epilepsy, and cerebral softening). Representing the normal condition of the ego by a horizontal line the mental departures from this line (degrees of alienation) are in the following order of increasing magnitude – viz., dementia praecox, paranoia, maniacal-depressive insanity, melancholia, phrenasthenic psychoses, and toxic and exhaustion psychoses. The insanity of puberty and adolescence, which occurs before the age of 30 years and very often before 20, sometimes may come on quietly and insidiously with a long period of pseudo-neurasthenia. Paranoia is a form of grave and progressive mental disorder which comes on after adolescence and has a tendency to a cyclical course in which there are at first depression, moodiness, suspicion, egotism, and a sense of being badly treated; then follow systematised delusions and sometimes active explosions of excitement. The course is long but there is very little tendency to dementia, for though the degree of alienation is great the organic deterioration of the brain is almost inappreciable. The condition known as maniacal-depressive insanity is harder to recognise. We see much melancholia but true acute mania is rare. But there is, adds Professor Dana, a depressive insanity which begins early in life, often develops from slight causes, and recurs again and again with slight tendency to dementia. The chronic melancholia of middle and later life is often heralded by a “history of nervous prostration or of obscure nervous attacks when in the twenties or later,” which have occasionally recurred. It can readily be understood that what is a pure psychosis, as is maniacal-depressive insanity in youth, may easily be made a chronic one by the complications and degenerative changes of later life. The late development of a psychosis such as this suggests that the constitutional taint underlying it is dying out, since violent mental confusion and tendencies to dementia are not seen in the pure forms of maniacal-depressive insanity in youth. The phrenasthenic psychoses form a “degenerative” group. It includes the mental and moral perversions, hysterias, phobias, aboulias, as well as morbid impulses and imperative ideas, and the many forms of dipsomania. With all patients of this class there is a tendency to “psychical storms or explosions” as in dipsomania, hysteria, and impulsive acts, or to fixity of morbid ideas, such as obsessions of fear, doubt, superstition, and the like. These patients are also neurasthenic on the somatic side. “I have been watching for a case of neurasthenia due to excessive physical work alone,” says Professor Dana, “but I have never seen it.” It does not occur – for example, as the result of long and hard athletic work, nor in bicycle races, or six-day pedestrians, or in firemen and stokers. “It is also the psyche that has to be hit in order to get a neurasthenia.” Neurasthenia, strictly speaking, very rarely occurs under twenty. What we see then is the pseudo-neurasthenia of dementia praecox, or dementia praecox itself, or slight attacks of recurrent maniacal-depressive insanity, or the initial symptoms of a developing phrenasthenia. The depressive and anxious types of neurasthenia occurring after the age of 40 or 45 years are usually mild forms of the involutional melancholia of middle age, while so-called congenital neurasthenia is usually a phrenasthenia, a dementia praecox, or a paranoia. Cutting out the foregoing, concludes Professor Dana, one has cut away about one-half of the great national malady attributed to America.