CIRCULAR INSANITY (Alternating insanity, Folie circulaire, Folie à double forme, Folie à formes alternes, Die cyclische Psychose, Das circuläre Irresein) consists in a psycho-rhythm or succession, in uniform order in each particular case, of (1) mental exaltation in all degrees, from mild exhilaration or even gayness to acute mania, and (2) mental depression of all conditions, torpor, or anergic stupor. These two opposite mental conditions are separated in the vast majority of cases by a shorter or longer interval of the normal mental state, in which, however, there is soon observed some mental impairment, however slight, rarely amounting to pronounced dementia except in old age. Sometimes the three states shade off into each other, so that it is difficult to say just where one begins and the other ends; less often the transition is abrupt, sometimes during sleep. The interval between the two opposite conditions of mind may succeed either of the other mental stages, but the order once established is maintained. The duration of the vicious circle varies in succeeding attacks, sometimes becoming longer, sometimes shorter, in the progress of the disease. The relative duration of the three succeeding mental condition also varies, but the type of each remains identical, or at least changes very gradually. The state of mental exaltation often resembles moral insanity, with all sorts of immoral impulses and tendencies, and may then properly be called an insanity of action. The depression sometimes goes no farther than sluggishness of will. The tendency of the disease is to shorten life only slightly, if at all, except from the chance of suicide in the depressed state and from exhaustion when the excited stage is one of active mania. The shortest duration of the cycle in my experience has been twenty-four hours, and the longest reported extends over several years. It sometimes remains an affective insanity in its whole course, without delusions and with little more dementia than might happen from simply a corresponding advance in age without mental disease. During the period of excitement some supervision or control will usually be desirable, and removal to some retreat or asylum will often be necessary. In the depressed stage the indications are to maintain the general health, to meet the chances of suicide, and if there are delusions to obviate the risks of danger to other persons. If the interval of comparative mental health is of considerable duration, the ordinary occupation of the patient can commonly be followed at that time for a number of years, rarely for life; but a better result may be looked for if the patient's circumstances are such that he can give up active and anxious work for some quiet occupation not involving great care.