First, bipolar spectrum disorders are likely quite heterogeneous with regard to their ease of diagnosis. It is generally much more difficult to elicit a history of bipolar II disorder or cyclothymia than of bipolar I disorder. The patient may think that the periods of elevated mood are simply a normal period of joy expressed when he or she recovers from the more obvious depressive episodes. On the other hand, persons prone to have a relatively changeable affect (e.g., those with borderline personality disorder) may erroneously report their very transitory (e.g., 1-hour) periods of excitement as hypomanic episodes. Furthermore, precisely because of the difficulty in detecting these illness subcategories, a good screening instrument is sorely needed. Thus, although the numbers of patients diagnosed with bipolar II disorder (N=26) or bipolar disorder not otherwise specified (N=13) in this study were much lower than those diagnosed with bipolar I disorder (N=70), it would be interesting to know how the instrument performed in detecting the subcategories of bipolar disorder in patients. I would speculate that while the overall sensitivity of the instrument in this study (0.73) is adequate, it might not be so for these subcategories.