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

4Bipolar I and bipolar II: a dichotomy?Eduard Vieta, Maria Reinares and Marc L. BourgeoisUniversity of Barcelona, Barcelona, SpainIntroductionThe distinction between unipolar and bipolar forms, rooted in the work of PierreFalret (1851) and Jules Baillarger (1854), was later established by Karl Kleist (1928,1953) and his school (Neele, 1949; Leonhard, 1957), and subsequently validated byAngst (1966), Perris (1966), and Winokur et al. (1969), who showed that clinical,familial, and course features supported the nosological differentiation betweenunipolar and bipolar disorders (Angst and Marneros, 2001; Marneros, 2001).However, there are many areas of overlap between those extremes, pointing upthe question of possible clinical subtypes in the interface of depressive and manicextremes of affective illness (Akiskal, 2002a).Bipolar disorder occurs in multiple forms and degrees of severity. The recognitionof the existence of so-called milder forms of manic-depressive illness has beena major endeavor in the last decade. The distinctions hinge on the classification ofelated states and this poses some difficulty because it depends on the arbitrarygradation of severity and duration. Bipolar disorder with mania and strict unipolardepression without manic or hypomanic episodes would represent the extremes ofa spectrum (Akiskal, 1983); recurrent depressions with hypomania would occupya middle territory (Akiskal, 2002b). Goodwin and Jamison (1990) point out thatthe exploration of spectrum models of manic-depressive illness would enhanceresearch on genetic markers and modes of genetic transmission, provide anapproach for identifying individuals at risk for the development of bipolar illness,and permit the evaluation of treatments for milder forms, including the questionof whether early intervention could lessen the chance of progression to bipolarillness. In fact, a great number of individuals with the so-called soft or subsyndromalstates belong to the bipolar spectrum by virtue of their positive familyhistories, their pharmacological response, and their tendency to progress to fullclinical disorder. Regarding nosological classification, Diagnostic and StatisticalManual of Mental Disorders, 3rd edn (DSM-III: American Psychiatric Association,# Cambridge University Press, 2005.