Mental derangement is often the prevalent symptom in diseases of the brain, produced by excess of masturbation or coition. We have already spoken of idiocy; but this is by no means the only change observed in consequence of these excesses. Every variety of affection of the mind may be caused by them, as is proved by statistics collected by several authors, in insane asylums. Yet these abstracts are far from presenting the truth. “So many circumstances combine,” says Esquirol, “to embarrass the discovery of causes of mental alienation, that the one mentioned, like other causes, must often be unascertained by physicians.” According to this sagacious observer of all the forms of mental alienation, mania is produced least frequently by venereal excesses. He adds, that maniacs, during the duration of the periods of access, are less addicted, generally, than other deranged persons to masturbation; but when they do indulge, this act must be considered as a bad symptom, since it constitutes an insurmountable obstacle to the cure: it destroys the strength, and finally produces in the patients stupidity, phthisis, marasmus, and death. Dementia is, perhaps, the kind of derangement most frequently observed after masturbation. I saw a remarkable instance of this disease in a young man, twenty years old, who, indulging in these excesses for several years, gradually lost his mental faculties, became averse to even his relatives and dearest friends, and finally fell into a most perfect state of dementia. The relative frequency of this form of mental alienation in onanists has been pointed out in France by Esquirol, and in Norway by Holst. (_Annales d’hygiene publ._ December, 1830.)