General paralysis not only is most frequent in the stronger sex, but it selects the strong individuals in the prime of life, between the ages of thirty-five and fifty. It is extremely rare under the age of twenty, although Turnbull has reported an unique case at the age of twelve;[23] it is not common under thirty or over sixty; I have seen two cases in men sixty-five years old. It is seldom seen in individuals who have been weak from childhood, unless as the probable result of syphilis. [Footnote 23: _Journal of Mental Science_, October 1881.] The excesses of the habits of the city and of mining and manufacturing centres, hard work, high living, late hours, predispose to general {178} paralysis in strong constitutions at the period of their greatest activity, especially if the physical strain, the violent struggle for existence, has begun early in life with insufficient food and excessive work, and if ordinary paralysis be not uncommon in the family. Alcoholic and sexual excesses are considered to be particularly common predisposing causes. Recent investigators find syphilis to be a part of the antecedent history of from one-half to three-fourths of the cases, but chiefly in those slowly advancing or subacute from the beginning. By some writers syphilis is considered to be in those cases only a diathesis, as is held by Fournier, or a debilitating antecedent, like chronic malarial poisoning. Others think that so large a proportion can be accounted for only by some specific relation between the two diseases. If the fact so often stated is true, that syphilis is rapidly increasing, perhaps part at least of the increase in general paralysis can be thus accounted for. Mental shocks of various kinds, excessive emotional strain with mental exhaustion, and injuries to the brain, are the commonly reported exciting causes of general paralysis, but it is not certain that—in many cases, at least—they do more than hasten the pathological process and call attention to the symptoms. So far as my observation goes, the injury to the head, supposed to be the cause of general paralysis, often has appeared to probably come from an accident due to the impaired physical strength and to the vaso-motor disturbance in the brain incident to the early stage of the disease and while it was still unrecognized. Cases are observed in which no predisposing or exciting cause is found by the physician. I have seen it following diphtheria and other debilitating diseases, after long exposure to malaria, and apparently due simply to prolonged mental strain in persons otherwise living in moderation under circumstances exceptionally favorable to health.