As most patients with a bipolar II disorder present to their GP during the depressed phase (generally melancholic in type, as noted earlier), all patients with depression should be screened for the possibility of a bipolar disorder. After obtaining details about their depressive symptoms, it is suggested that GPs ask the patient, ‘Do you have times when you are neither depressed nor in a normal mood state but feel highly energised and wired?’ (the terms ‘energised’ and ‘wired’ going to the heart of a hypomanic or manic episode).
If these initial probe questions are not affirmed, it may be helpful to ask one or two additional screening questions, using synonyms for ‘energised’ and ‘wired’ and, if these are denied, you may feel relatively comfortable about excluding a bipolar disorder. If the probe question is affirmed, you can follow up with a series of specific questions (Box). Those with a true bipolar II condition will acknowledge most of the symptoms described in these specific questions but deny any psychotic features.
Next, ask whether there was a ‘trend break’ when such symptoms appeared and became distinctive; most patients will report the onset of such ‘highs’ in adolescence or early adulthood. Then, ask about the average length of ‘highs’ and depressive episodes. Also pursue a family history of depression or bipolar disorder. About 80% of patients with a true bipolar II condition report such a history in first- and/or second-degree relatives, while about 10% report a family history of suicide.
As noted earlier, most people with a bipolar II disorder experience episodes of melancholic depression; therefore, weight such features (along with the hypomanic symptoms) in making the diagnosis. Key features of melancholic depression include a severely anhedonic and nonreactive depressive mood, anergia (particularly having difficulty in getting out of bed), ‘foggy’ (impaired) concentration and diurnal variation (with mood and energy worse in the mornings).
Although bipolar II disorder is generally positioned as a ‘milder’ condition than bipolar I, the suicide rate is higher among patients with bipolar II disorder, probably reflecting the precipitous descent from a ‘high’ into a depressive episode experienced by these patients (compared with a slower mood drop in those with a bipolar I disorder), and the individual dreading going back to such a state.
As noted, DSM-5 criteria effectively underestimate the likelihood of bipolar II disorder. First, DSM-5 requires that the hypomanic episodes last four or more days, with that impost reflecting opinion rather than empirical studies. Research has shown that many people with a true bipolar II disorder will have episodes lasting hours or a couple of days only. If the DSM-5 duration criterion is imposed, up to 60% of people with a true bipolar II disorder will not receive the diagnosis.
Second, DSM-5 requires that there must be a level of impairment – at variance with the evidence that up to 70% of people with a bipolar II condition report improved performance, which explains why so many people with a bipolar II disorder are highly successful and reach the heights of their profession (including six former British prime ministers2).