Whether you work in a hospital or an office setting, you’ve probably seen many patients who come to you with a “history of bipolar disorder.” We’ve seen it, too, in multiple settings at an academic medical center. Is this a new epidemic? Or a redefinition of what it means to be “bipolar”?

Some argue that bipolar disorder is actually under-diagnosed. They have support from abundant literature showing that bipolar disorder tends to present more often with depression than mania or hypomania (Judd LL et al, Arch Gen Psychiatry 2002:59(6):530–537). As many as 10% of patients with unipolar depression ultimately are shown to have bipolar illness instead, according to some experts (Goodwin GM et al, Eur Neuropsychopharm 2008:18(7):535–549). (See this month’s Q&A with Claudia Baldassano for more on this.) In addition, a new emphasis on subthreshold mood symptoms and more rapid mood shifts has led some psychiatrists to promote the concept of a “bipolar spectrum disorder” (Youngstrom EA et al, Curr Psychiatry Rep 2010;12(6):479–489).

The pro-bipolar spectrum camp maintains that our definition of “bipolar” simply needs to be revised. Some have redefined “bipolarity” to include overactivity without mood changes; hypomanic episodes as short as one day; and a family history of mood disorder (Angst J et al, J Affect Disord 2003;73(1–2):133–146). Using these and other factors, loosely known as the “Zurich criteria,” Angst and colleagues found that, among 5,000 patients in a current depressive episode, a surprising 47% met their redefined “bipolar” criteria, compared with only 16% using DSM-IV criteria (Angst J et al, Arch Gen Psychiatry 2011:68(8):791–799). In a separate study, when patients with major depressive disorder were asked about “subthreshold hypomania” symptoms, nearly 40% could be relabeled “bipolar” (Angst J et al, Am J Psychiatry 2010:167(10):1194–1201).

While it’s important to remain vigilant about a history of manic and hypomanic symptoms, we think the problem of over-diagnosis is probably greater. For instance, in a 2008 study, Zimmerman and colleagues performed a comprehensive diagnostic interview on 700 patients, nearly 21% of who self-reported a history of “bipolar disorder.” However, when using the gold-standard SCID (structured clinical interview), only 13% had the diagnosis; they also had more first-degree relatives with bipolar disorder than the others (Zimmerman M, Ruggero CJ et al, J Clin Psychiatry 2008:69(6):935–940). The authors hypothesized that over-diagnosis of bipolar disorder might be a consequence of efforts to improve recognition of it and avoid under-detection. In fact, the same authors studied 40 depressed patients previously diagnosed with bipolar disorder and found that, by the SCID, they had specific phobia, PTSD, drug abuse/dependence, or a personality disorder instead (Zimmerman M et al, Compr Psychiatry 2010;51(2):99–105).

“Subthreshold hypomania,” assuming such a thing truly exists, is a condition that few clinicians are likely to take the time to diagnose properly—not to mention the fact that the criteria are broad and evolving. For instance, Appendix A of the Zurich interview includes nearly 40 items, such as “less sleep” and “more enthusiasm for work.” The busy clinician will probably not take the time to ferret out the subtypes, and, instead, jump to the “bipolar” label. Furthermore, since “episodes” can last as little as one to three days under these criteria, it’s no surprise that patients who describe their moods as “flipping every few minutes” might be diagnosed—or, more likely, misdiagnosed—bipolar.

Over-diagnosis can also occur when apparent mood episodes are defined as psychiatric when in fact they have a different etiology altogether. Decreased need for sleep, disorganized or racing thoughts, increased activity and agitation, and delusional thinking, even when they occur together, can represent a sort of “final common pathway” for medical conditions and other syndromes. The manic phenotype can occur in patients with agitated delirium, brain tumors, corticosteroid treatment, and of course substance intoxication (Bunevicius A et al, CNS Spectr 2008;13(11):950–958; Brooks JO and Hoblyn JC, Am J Psychiatry 2005;162(11):2033–2038). These other phenotypes can be distinguished by recognition of key features such as the fluctuating nature of consciousness in delirium, neuroimaging findings, and positive urine drug screens.

The growing public awareness of bipolar disorder, as well as media portrayals that have destigmatized the illness, have also contributed to a wave of individuals who “want to be bipolar” (Chan D and Sierling L, The Psychiatrist 2010;34(3):103–105). For many, it is less stigmatizing to be diagnosed with bipolar disorder than with another cause of mood swings, such as a personality disorder. Another source of over-diagnosis is “Dr. Google,” ie, patients who have self-diagnosed from the Internet. Accurate or not, the label sticks for years—particularly when it appears in the patient’s medical record—while treatment with multiple medications tends to reinforce the sticky label.

Unfortunately, physicians may also be susceptible to diagnostic shortcuts. When faced with limited time for diagnostic interviews and the pressure to prescribe by patients and their families, well-meaning clinicians may give the diagnosis after a single brief interview. Not uncommonly, we find that it was diagnosed on the basis of mood fluctuation over minutes, temper tantrums, and fleeting insomnia. The rapidly expanding repertoire of medications approved for bipolar disorder, and their relative ease of use, may also contribute to over-diagnosis. Unfortunately, in some cases the treatment may be worse than the symptoms themselves (Iordache I and Low NC, J Psychiatry Neurosci 2010;35(3):E3–4).

Ultimately, some patients become attached to their bipolar diagnosis. Is the patient’s husband more likely to help with the kids when mom is having a “manic moment”? Helping them let go of a label and the associated treatment, which can include complex polypharmacy and side effect burdens, can include a number of psychotherapeutic approaches. Providing validation and education can be done even in busy psychiatry clinics. Motivational interviewing is a flexible yet powerful style for helping someone move toward change. And paying attention to the needs of the person behind the diagnosis is always a good idea.

TCPR Verdict: 
We can avoid the trap of under-diagnosing or over-diagnosing bipolar disorder by maintaining a respectful skepticism and basing our diagnosis on serial evaluations over many follow-up visits to establish a longitudinal course of illness. Close attention to the evolving literature in this field may help shape our understanding of bipolar disorder and the best ways to diagnose and manage this condition.