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Ask the Mental Health Expert Archives 2001-2004

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Atypical Bipolar Disorder?

Q. I am an attorney and have a client suffering from conditions similar to bipolar disorder. Is there such a thing as "atypical bipolar disorder"? Is it just a commonly used phrase for bipolar disorder NOS (not otherwise specified)?

A. There is no such diagnosis as "Atypical Bipolar Disorder" in the strict sense of an official DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4th ed.) diagnosis. However, the DSM-IV does use the specifier, "with atypical features" for both unipolar and bipolar depressive episodes (see pp. 385-86 of DSM-IV).

Atypical features include, e.g., mood reactivity, significant weight gain, hypersomnia, leaden paralysis, and rejection sensitivity. The fact is, many bipolar patients will typically show atypical features, such as weight gain and excessive sleep during their depressive phases--so the specifier is somewhat redundant.

On the other hand, Bipolar Disorder NOS (not otherwise specified) covers a poorly defined and broad array of possibilities--essentially any type of bipolar-like condition that does not fit criteria for the standard diagnoses. One example would be an individual who does not meet formal DSM-IV criteria for hypomania (which requires at least four days duration) but does show periods of mood elevation lasting, say, two days at a time.

Other examples are given on p. 366 of the DSM-IV (1994) text. A lot of clinicians probably speak casually of atypical bipolar disorder, whereas they would code it as Bipolar Disorder NOS on an official form. There is also the concept of the Bipolar Spectrum, which is even broader than Bipolar NOS-for information on that, you might read the paper by Hagop Akiskal (Akiskal HS: The prevalent clinical spectrum of bipolar disorders: beyond DSM IV. J Clin Psychopharmacol 1996; 16[suppl 1]:4-14.).

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April 2003

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