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

5Recurrent brief depression as an indicator ofsevere mood disordersJules Angst, Alex Gamma, Valadeta Ajdacic, Dominique Eich,Lukas Pezawas and Wulf RösslerZurich University, Psychiatric Hospital, Zurich, SwitzerlandIntroductionBipolar spectrumThe bipolar spectrum is currently the focus of very intensive research, which ishampered by two interrelated biases, one methodological and one commercial.Epidemiological and clinical research in the field of bipolar disorders deals withdisorders/syndromes defined according to the diagnostic manuals and uses methodstailored to them, which are not suitable for assessing subthreshold morbidity(minor and recurrent brief depression, recurrent and brief hypomania). This hassignificant implications for the differentiation between depression and bipolardisorder. As a consequence, major depressive disorders (MDD) are overdiagnosedand heterogeneous; they include many bipolar II (BP-II) cases, of which thehypomanic component does not reach the Diagnostic and Statistical Manual ofMental Disorders (DSM-IV: American Psychiatric Association, 1994) orICD-10Classification of Mental and Behavioural Disorders (World Health Organization,1992) diagnostic threshold for hypomania. This means that drug trials selectingpatients on the basis of an MDD diagnosis are also dealing with heterogeneousgroups, which include hidden BP-II subjects prone to switch into hypomania.Moreover, current bipolar research is biased towards mania and neglects bipolardepression. The large majority of modern treatment studies on mood stabilizersselect patients with mania and exclude those with BP-II disorders, although thelatter are much more prevalent than the former both in clinical practice andamong relatives of bipolar patients. In addition, BP-II patients have traditionallybeen excluded from drug trials using modern antidepressants.As we have found, bipolar subjects identified by diagnostic criteria ofDSM-IV (American Psychiatric Association, 1994) or ICD-10 (World HealthOrganization, 1992) form only the tip of the iceberg of the bipolar spectrum;below the diagnostic threshold are a large number of subjects with unidentified# Cambridge University Press, 2005.