Letters to the Editor
Re: Clinical and Family History Markers of Bipolar II Disorder
Dear Editor:
We thank Dr Benazzi for his letter. He reviews previous studies that support associations between what we call bipolar spectrum disorder (BSD) and early-onset, atypical features, and mixed mood symptoms. He also applies our proposed definition to its first empirical test and finds excellent sensitivity for recurrent depressive episodes (3 or more), together with good specificity for atypical depressive features and mixed mood symptoms. We appreciate Dr Benazzi’s careful empirical assessment. This is exactly the kind of empirical test that we hoped our heuristic definition of BSD would stimulate. We only hope that Dr Benazzi and other investigators will continue these studies, so that the criteria can be further refined empirically.
We wish to highlight 2 aspects of our proposal. On the one hand, we describe features of depressive symptoms, course, family history, and treatment response. We propose that these features outline a group of depression patients who have neither classic unipolar nor classic bipolar disorder (BD); that is, they never display spontaneous mania or hypomania. However, a unipolar diagnosis broad enough to encompass such patients may offer little in the way of predictive validity. These patients, in fact, have many more diagnostic features in common with BD than with unipolar depression. We therefore suggest the term BSD for this group, and we advocate empirical tests of our definition. Conversely, as Dr Benazzi also emphasizes, our proposed definition can be seen as a way of assessing patients who may be at high risk for having BD or later developing the disorder, especially BD II. If patients have many of the bipolar spectrum depressive features we highlight, closer examination may reveal past episodes of hypomania (or sometimes even mania) that either have been denied or have escaped detection. Further, such patients may be at high risk for future spontaneous hypomanic or manic episodes and thus may warrant careful assessment for such symptoms longitudinally. Hence, our list of bipolar spectrum symptoms can also be seen as clues for bipolarity that, if present, warrant an even more extensive evaluation for hypomanic or manic symptoms in a patient who does not appear to have BD.
In any case, we wish to emphasize that these are testable hypotheses, and we welcome and request the type of empirical examination that Dr Benazzi has inaugurated.
Nassir Ghaemi, MD;
James Y Ko, AB;
Frederick K Goodwin, MD
Cambridge, Massachusetts
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