The term partial insanity comprises chiefly those varieties known as impulsive, emotional, and moral. Somewhat akin to these forms are those associated with such general diseases of the nervous system as epilepsy, hysteria, and neurasthenia. When insanity takes the form of a general enfeeblement of the mental faculties as a consequence of disease, it is called dementia. It is usually permanent. Its principal varieties are senile, paralytic, and syphilitic.
Paresis is one kind of paralytic dementia.
All the above-mentioned forms of insanity are acquired, in the sense that they occur in normally developed brains. Congenital insanity, or feeble-mindedness, is divided chiefly, according to its degrees, into imbecility, idiocy, and cretinism. That insanity is on the increase, seems to be the general verdict of authorities, although the absence of reliable and comprehensive statistics makes any satisfactory estimate impossible. Whatever be its extent, the increase is undoubtedly due in some measure to our more complex civilization, especially as seen in city life. Among the exciting causes must be mentioned shock, intense emotion, worry, intellectual overwork, diseases of the nervous system, exhausting diseases, alcoholic and sexual excesses, paralysis, sunstroke, and accidental injuries.