PRIMARY MENTAL DETERIORATION or PRIMARY BRAIN ATROPHY is a term suggested for a curable impairment of the mind arising from brain-exhaustion in persons, usually men, between the ages of from fifty-five to sixty-five. I have found it in some cases associated with interstitial nephritis and with degenerative disease of the walls of the heart, and have suspected atheroma of the cerebral arteries or possibly endo-arteritis of specific or other origin. It occurs at a time when atrophy of the brain is naturally taking place. There are the usual indications of physical wear and such marked deterioration of the mental powers as to {171} seriously interfere with the capacity to attend to customary business and every-day duties, and to closely simulate the early stage of paralytic dementia. There occur also, in a certain proportion of cases, epileptiform convulsions, slight attacks of dizziness, petit mal, and always disappearance of sexual power and desire. There may or may not be headache. The patient recognizes his condition, his mental depression does not far exceed the physiological limit, and there is no reasonable risk of suicide, except from reasons which would impel a sane man to it. Under the influence of rest, if begun early, tonics, and a strict regard to the laws of health the symptoms commonly disappear if there is no organic disease. I have never seen the brain recover its tone to the extent of making it safe or even possible to resume the previous kind and amount of work. In a certain proportion of cases there is striking mental impairment, even dementia, and the primary atrophy of the brain sometimes makes rapid progress to unconsciousness and death. It is not possible to say, by the degree of atrophy found post-mortem, whether there was or was not primary mental deterioration during life. The TREATMENT consists in entire freedom from care, rest from work, travel, tonics, etc. As mental disease is more than a brain disease, and is a disease of the intellect, each age from infancy up (and each individuality) impresses its peculiar mark upon it, and there are certain terms in common use to express insanity associated with certain physiological processes whose meaning should be explained. INSANITY OF CHILDHOOD is for the most part only a further development of a congenital state of mental defect. I have seen, however, well-marked mania, melancholia, primary dementia, and primary delusional insanity before the age of puberty. Typical acute mania I have seen twice in children two years old, apparently arising in normal brains after severe injuries to the head. This is quite uncommon, and the number of cases thus far observed is too few to make me feel sure that my own experience of a favorable result as to recovery in uncomplicated cases will be generally confirmed. At best, after a cure there is a more or less decided arrest of brain development.