Academic journal article Hong Kong Journal of Psychiatry

A Short Review on the Diagnostic Issues of Bipolar Spectrum Disorders in Clinically Depressed Patients-Bipolar II Disorder

Academic journal article Hong Kong Journal of Psychiatry

A Short Review on the Diagnostic Issues of Bipolar Spectrum Disorders in Clinically Depressed Patients-Bipolar II Disorder

Article excerpt

Background

The last decade saw an awakening to the Kraepelinian continuum between manic and depressive states (1) in affective disorder research. Based on clinical observations, longitudinal follow-up, and family history, Kraepelin was able to identify patients who had mania and depression, others with depression who only had hypomania but never manic episodes, and yet others pursuing a cyclical course with temperamental manic-depressive features. These observations supported Kraepelin's unitary view of manic-depressive illness. The latter was conceived to be a single morbid process with various clinical expressions, linked by common temperamental and genetic factors.

Recent epidemiological evidence and clinical observations have revived the bipolar spectrum concept. (2) Community prevalence of bipolar spectrum disorders of 5 to 8.3% have been reported. (3) This constituted a large increase (1.2-1.6%) for studies reporting narrowly defined bipolar disorders, as in the Epidemiologic Catchment Area study, (4) and the National Comorbidity Survey. (5) The screening module of the World Health Organization Composite International Diagnostic Interview for bipolar disorder and sub-threshold bipolar conditions was validated by blind reappraisal with the non-patient version of the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders--4th edition (DSM-IV) [SCID]. Using that screening module, the National Comorbidity Survey Replication Study yielded a 6.6% lifetime prevalence for bipolar spectrum disorder. (6) The increased recognition of bipolar disorder translates into treatment needs which must be qualified in terms of clinical phenomenology, illness outcome, and health risks. Between bipolar I and the rest of the soft bipolar spectrum, bipolar II disorder has been the only diagnostic category recognised in the DSM-IV. (7)

What follows is a selected literature review with the aim of examining the clinical validity of bipolar II disorder from the perspectives of psychopathology, prevalence and outcome, and their significance with respect to nosology. Articles were retrieved from a MEDLINE search under the Medical Subject Heading of 'bipolar disorder', published from 1966 to January 2007. Articles concerning the psychopathology, prevalence, clinical correlates, and outcome of bipolar II disorder were then selected for review. Since the focus of this review was on clinical diagnostic and nosological conceptual issues, genetic, neuroimaging, and treatment studies were not reviewed, which may represent a shortcoming worthy of focus in another review.

Beyond Bipolar I--Psychopathology of Bipolar II Disorder

Bipolar II disorder has been defined as the occurrence of spontaneous hypomania in patients with clinical depression. The distinction between bipolar I and II was first made by Fieve and Dunner (8) in their seminal article, which distinguished hypomania from mania by the latter's need for hospitalisation. Despite initial controversy about its nosologic status, subsequent epidemiological and clinical studies have provided a solid foundation for regarding bipolar II as a prevalent and phenomenologically distinct disorder. A family epidemiological study found bipolar II to be the commonest bipolar phenotype among 266 first-degree relatives of bipolar I and II probands, suggesting that it may be the commonest form of bipolar spectrum disorder, (9) and longitudinal follow-up studies yielded strong diagnostic stability. (10,11) In a 10-year follow-up study of bipolar I, II, and unipolar depressed patients, only 7.5% of bipolar II subjects defined at entry developed full-blown mania over a 10-year follow-up. (12) This provided support for bipolar II as a phenomenologically stable diagnosis, rather than a transitory state between bipolar I and unipolar depression.

Based on longitudinal follow-up data on 163 patients with primary affective disorders, Dunner et al (13) found patients with both history of hypomanic episodes and clinical depression to have a distinctly stormy and variable course with high suicidality. …

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