The bipolar spectrum--a bridge too far?
OBJECTIVE
To review the literature evaluating outcomes resulting from expansion of the bipolar disorder (BD) diagnostic category. We were particularly interested in identifying high-level evidence for improved clinical outcomes as documented by randomized controlled trials (RCTs) or cohort studies.


METHODS
The English-language literature was searched using Ovid MEDLINE for studies of BD referenced against the key word spectrum. We used bibliographies and other databases to extend this search when no relevant RCTs or relevant cohort studies were identified.


RESULTS
In the MEDLINE searches, abstracts and titles of 86 studies were examined and 48 were found to be related to the topic of bipolar spectrum disorders (BSD). No RCTs or prospective cohort studies evaluating modified diagnostic or therapeutic practices were identified. The literature about the BSD consists mostly of expert opinion emphasizing: various links between bipolar and unipolar mood disorders; a proposal that a greater proportion of the population without a mood disorder as defined by the Diagnostic and Statistical Manual of Mental Disorders should be diagnosed under the BD category; and, proposals that syndromes currently classified elsewhere should be subsumed under the BD category.


CONCLUSIONS
Our search failed to uncover high-level evidence demonstrating the clinical utility of proposed diagnostic realignments. The widespread acceptance of the expanded spectrum concept appears to be based on interpretation of descriptive epidemiologic data by high-profile experts.
Patten
Scott B
SB
Department of Community Health Sciences and Psychiatry, University of Calgary, Calgary, Alberta. patten@ucalgary.ca
Paris
Joel
J
D001714:Bipolar Disorder / Q000175:diagnosis*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D006801:Humans