Bipolar Disorders: Mixed States, Rapid-Cycling, and Atypical Forms

54 G. Perugi and H. S. Akiskal3020.3Percent2012.414.8100Chronic episodesMania (n = 155) Depression (n = 165) Mixed state (n = 143)Fig. 2.2Rates of chronic episodes (length < 2 years) in bipolar patients. Data from Perugi et al.(2000).The rate of chronic episodes, defined as a duration of the current episode lastingmore than 2 years, seems to be higher in MS than in mania and major depression(Perugi et al., 2000; Fig. 2.2). Frequent chronic evolution was reported byKraepelin (1899), in his original description, as a specific clinical feature of MS.Furthermore, as described by Keller et al. (1986) and Perugi et al. (2001b), theprognosis of MSs in terms of interepisodic symptomatology is worse than that ofnon-mixed episodes.In considering the frequent coexistence of MS with long-lasting subaffectivesymptomatology, the role of temperamental disposition in the development of MSis a relevant factor (Akiskal, 1992). Affective temperaments, as conceived in theclassical psychiatric literature (Kraepelin, 1899; Kretschmer, 1936) and morerecently formulated (Akiskal et al., 1979), refer to subaffective trait expressionsthat represent the earliest subclinical trait phenotypes of affective disorders, andwhich persist as the subthreshold interepisodic phase of these disorders. Theidentification of depressive, hyperthymic, cyclothymic, and irritable temperamentalattributes has important implications not only for the classification of mooddisorders, but also for their prevention, treatment, and prognosis.We will now consider more fully the implications of the provocative hypothesisthat derives MS from a temperament opposite to the polarity of the affectiveepisode (Akiskal, 1992). Dell’Osso et al.(1991, 1993) have reported data in partialsupport of this hypothesis. In our study (Perugi et al., 1997), mania seems to arisefrom a hyperthymic background; by contrast, MS seems to arise from a depressiveor hyperthymic disposition and, more tentatively, when traits of the two