There is considerable debate over whether bipolar and related disorders
that share common signs and symptoms, but are currently defined as distinct
clinical entities in DSM-IV and ICD-10, may be better characterized as falling
within a more broadly defined “bipolar spectrum”. With a spectrum
view in mind, the possibility of broadening the diagnosis of bipolar disorder
has been proposed. This paper discusses some of the rationale for an expanded
diagnostic scheme from both clinical and research perspectives in light of
potential drawbacks. The ultimate goal of broadening the diagnosis of bipolar
disorder is to help identify a common etiopathogenesis for these conditions
to better guide treatment. To help achieve this goal, bipolar researchers
have increasingly expanded their patient populations to identify objective
biological or endophenotypic markers that transcend phenomenological observation.
Although this approach has and will likely continue to produce beneficial
results, the upcoming DSM-IV and ICD-10 revisions will place increasing scrutiny
on psychiatry’s diagnostic classification systems and pressure to re-evaluate
our conceptions of bipolar disorder. However, until research findings can
provide consistent and converging evidence as to the validity of a broader
diagnostic conception, clinical expansion to a dimensional bipolar spectrum
should be considered with caution