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

270 P. Briegerfundamental question of concept and phenomenology, and not a question ofcomorbidity.The general effect of comorbidityThe majority of patients with a bipolar affective disorder and a co-occurringpsychiatric disorder suffer from more than one additional disorder (McElroyet al., 2001; Vieta et al., 2001). In one analysis from the Stanley FoundationBipolar Treatment Outcome Network, 35% of all bipolar patients (n ¼ 288) hadno lifetime comorbid Axis I disorder, 23% had one such comorbid disorder, 18%had two, and 24% had three or more. With regard to current comorbid Axis Idisorders, the numbers were as follows: 67% had none, 20% had one disorder, 7%had two disorders, and 6% had three or more disorders (McElroy et al., 2001).In another comparison of bipolar affective patients (n ¼ 129) with or without acurrent comorbid psychiatric disorder (Vieta et al., 2001), patients with a currentcomorbid disorder had a history of significantly more mixed episodes thanpatients without such current comorbid disorders. In our follow-up study(n ¼ 149), we came to the same result (Brieger et al., in preparation). Both studieshave included Axis I and II disorders and, in our study, this difference is primarilythe effect of an excess of cluster C personality disorders in the group of patientswith previous mixed episodes. Interestingly, the Stanley Foundation BipolarTreatment Outcome Network study (McElroy et al., 2001), which looked at onlyAxis I disorders and not at personality disorders, found no significant differencebetween patients with or without such comorbid diagnoses in regard to dysphoricmania, whether one looked at lifetime or current comorbidity.The Stanley Foundation Bipolar Treatment Outcome Network study (McElroyet al., 2001) indicated that patients with comorbid Axis I disorders show morecycle acceleration and possibly more rapid cycling. The latter result barely missedstatistical significance, but the study used strict correction for multiple comparisons;therefore, this may have been a false-negative result. Vieta et al. (2001) didnot come to the same result, but here the smaller sample size has to be considered.ConclusionsComorbidity research illustrates the shortcomings of the present diagnosticsystems and must therefore go further than merely describing present rates ofco-occurring disorders. Instead, it has to uncover trends, relationships, and linksbetween different disorders. Even if one were to suppose that the different definitionsof mixed episodes and of rapid cycling described two widely homogeneousgroups, the present review does not give much support for the idea that such forms