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

110 J. Angst et al.DSM-IVZurich:hard criteriaZurich:soft criteriaBP-IBP-II0.5%0.4%BP-I0.5%BP-I0.5%BP-II5.3%BP-II11.0%MDD21.3%MDD11.4%Hypom+cycloDyst1.2%1.3%MajorMinorMDDHypomMin BPDystMild D17.1%Major3.3%3.2%1.3%Minor19.4%HypomMinBPDystMild D3.3%9.4%0.7%13.2%Total 24.7%48.8% 48.8%ratiodep/BP 10.8 3.0 1.0Fig. 5.1Cumulative prevalence rates of the bipolar spectrum. BP-1, bipolar disorder I; MDD, majordepressive disorder; Hypom, hypomania; Dyst, dystonia; D,/Dep, depression; BP, bipolar;DSM-IV, Diagnostic and Statistical Manual of Mental Disorders. Reprinted with slightmodifications from Angst, J. and Gamma, A. (2002). Prevalence of bipolar disorders:traditional and novel approaches. Clin. Approaches Bipolar Disord., 1, 10–14, by permissionof Cambridge Medical Publications.BP-II, minor bipolar disorders, and hypomania (Angst et al., 2003a; Angst andGamma, 2002). Figure 5.1 illustrates the cumulative prevalence rates of the bipolarspectrum, with its subgroups, as diagnosed in the Zurich study across six interviewsfrom the age of 20 to 40 (Angst et al., 2003a; Angst and Gamma, 2002). The tip ofthe iceberg consists of 0.55% BP-I disorder, below which we found 5.3% BP-IIdisorders defined by hard Zurich criteria and a further 5.7% suspected BP-II casesdefined as major depressive episodes (MDE) with hypomanic symptoms. In thesame paper, we also proposed a new group of minor bipolar disorders (MinBP)with a prevalence rate of 3.2% (hard definition) and 6.2% (soft definition). Thisimportant MinBP group consists of depressives (dysthymia, minor depression,and recurrent brief depression (RBD)) who, in addition, manifested hypomanicsyndromes (hard definition) or hypomanic symptoms (soft definition).Figure 5.1 shows that a hard definition of bipolarity identifies about one-quarterof all mood-disorder cases as bipolars, whereas a soft definition, including suspectcases, identifies about half of such cases as bipolars. This finding is especially relevantin regard of MDD, which was found to be no more prevalent than BP-II disorders. Asoft definition of BP-II disorders enables us to identify most hidden bipolar cases,which are usually misdiagnosed as MDD. For more details, see Angst et al. (2003a).