"The diagnosis should be restricted to mental disorders arising as a direct or obvious consequence of a brain (or head) injury producing psychotic symptoms of a fairly characteristic kind. The amount of damage to the brain may vary from an extensive destruction of tissue to simple concussion or physical shock with or without fracture of the skull. "Manic-depressive psychoses, general paralysis, dementia praecox, and other mental disorders in which trauma may act as a contributory or precipitating cause, should not be included in this group. "The following are the most common clinical types of traumatic psychosis and should be specified in the statistical record of the hospital:— "(a) Traumatic delirium: This may take the form of an acute delirium (concussion delirium), or a more protracted delirium resembling the Korsakow mental complex. "(b) Traumatic constitution: Characterized by a gradual post-traumatic change in disposition with vasomotor instability, headaches, fatigability, irritability or explosive emotional reactions; usually hyper-sensitiveness to alcohol, and in some cases development of paranoid, hysteroid, or epileptoid symptoms. "(c) Post-traumatic mental enfeeblement (dementia): Varying degrees of mental reduction with or without aphasic symptoms, epileptiform attacks or development of a cerebral arteriosclerosis. "(d) Other types." We have not as yet, unfortunately, sufficient data at our disposal to warrant intelligent conclusions as to the frequency of the various forms of traumatic psychoses. One hundred and twenty-seven cases reported from the New York state hospitals during a period of six years were classified as follows:— _Form_ _Number_ _Per cent_ Traumatic delirium 38 29.32 Traumatic constitution 32 25.19 Post traumatic mental enfeeblement 32 25.19 Others, not specified 25 19.70 Undoubtedly with a more definite understanding as to the delimitation of these different conditions more complete information will be available later. We are nevertheless justified in feeling that the frequency of the traumatic psychoses considered as a group can be determined with a fair degree of accuracy. Of 49,640 first admissions to the New York hospitals during a period of eight years, 161, or .32 per cent, were definitely ascribed to traumatism. Twenty-one other hospitals in fourteen different states reported forty-five cases of traumatic psychoses (.24 per cent) in 18,336 admissions. Two hundred and seventeen cases (.3 per cent) have therefore been reported in a total of 70,987 first admissions to forty-eight state hospitals for mental diseases in this country. CHAPTER II THE SENILE PSYCHOSES