Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders: major depression summary

In reply:

Zimmerman laments that bipolar disorder is not integrated into the major depression summary of the Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders,1 and that it “omits discussion of bipolar disorder”, because the summary “is likely to be used as a stand-alone guideline by primary care physicians treating depression”. Curiously, this comment suggests that primary care physicians will read the depression summary but fail to realise it has been abstracted from a much larger guideline2 and needs to be considered alongside an accompanying summary on bipolar disorders,3 even though the introductory paragraphs of both summaries state these points clearly!

The original guidelines, which consider the full spectrum of mood disorders, are more than 100 pages long and state that the “reason for addressing both groups of mood disorders together is that … they have been conceptualized as part of a spectrum” and that “a unified approach to the diagnosis and management of mood disorders has been adopted in this guideline”.2 Further, when considering a diagnosis of major depression, the summary underscores the importance of bipolar disorder as the only key differential (Box 1, E in the summary).1 Thus, while constructive commentary on the summaries is welcome, Zimmerman’s criticisms are not only inaccurate but run the risk of encouraging misdiagnosis.

By considering bipolar disorder prematurely, the real concern is that of overdiagnosis, in particular of bipolar II disorder. This is because, clinically, bipolar disorder usually heralds its presence with depressive episodes, but, as yet, there are no signs or symptoms that can reliably distinguish these from recurrent major depression (prospectively or even in retrospect). Although encouraging clinicians to suspect bipolar disorder is appropriate, suggesting that this possibility should be communicated to patients and their relatives at the earliest opportunity is ill advised. The diagnosis of bipolar II disorder is complicated — partly because it is poorly defined. Hence, in practice, bipolar II disorder is easily confused with symptoms of marked anxiety — occurring alongside those of major depression or affective instability — presenting as part of personality dysfunction in the context of depressive symptoms or substance misuse. Therefore, a diagnosis of bipolar disorder needs to be deliberated on carefully and, ideally, from a longitudinal perspective. It should only be assigned and treated when there is sufficient evidence to unequivocally support a diagnosis of bipolar disorder. This is critical because an incorrect diagnosis — especially of bipolar II disorder — can be difficult to reverse or even revise, and the need for such depolarisation can be avoided.4