DSM focuses on the difference between Bipolar I and II. But there’s another way to categorize the illness that may have more relevance to treatment.
Table. Signs of classic and atypical bipolar disorder
While I appreciate the DSM, the diagnostic manual missed 2 categories of bipolar disorder that are particularly relevant to treatment. They are classic and atypical bipolar.
In classic bipolar disorder, hypo/manic and depressive symptoms are clearly separated, without much overlap. Affected patients are so responsive to lithium that Terrence Ketter proposed calling their disorder Cade’s disease, in homage to the Australian psychiatrist who discovered lithium.1 Other signs of classic bipolar disorder are listed in the Table. Patients need not have all these signs, but lithium is a good option if these features predominate.2
The alternative form of bipolar doesn’t have an official name, but a textbook on the subject called it atypical bipolar, after the DSM-III term for other specified bipolar.3 I’ll revive that wording here, though I also intend to clarify its definition a bit.
Atypical bipolar is marked by mixed states, rapid cycling, and a lack of full recovery between episodes. These patients are more responsive to anticonvulsants and atypical antipsychotics, but lithium should not be ruled out as it may work for them as well.4,5
The atypical and classic forms have opposite features (see Table).6,7,8 The atypical form is often missed in practice but-ironically- it is more common than the textbook case of classic bipolar. Even Emil Kraepelin, who wrote the original textbook on manic depression, noted the high frequency of these atypical forms and complained that his colleagues were more interested in “pure forms” of the illness.8
These 2 categories can apply to patients with bipolar I or II, although the atypical form is more common in bipolar II. Still, look out for those classic bipolar II cases, the ones who enjoy their hypomanias, as lithium is often neglected in them-and not with good reason. One study found that lithium worked better in bipolar II than bipolar I, by a factor of 6.9
The role of psychotherapy
Patients with atypical bipolar often present with anxiety and other comorbidities that are best treated with psychotherapy to avoid the mood-destabilizing risks of an antidepressant. Their childhoods are marked by trauma, adolescence derailed by the early onset of bipolar, and adult lives colored with stormy relationships and temperamental instability – all good reason to recommend therapy. In contrast, those with classic bipolar tend to have healthier personalities, which can pose a risk of its own. These confident, action-oriented patients often stop their medication, believing they can stay well on their own.
A diagnostic tool
Atypical bipolar is often missed because its mixed features obscure the core symptoms of hypo/mania. Even when manic symptoms are endorsed, they are often explained away by the comorbidities, such as impulsivity from addictions or borderline personality; hyperactivity from ADHD; racing thoughts from anxiety; or irritability from PTSD.
The key, then, is to look beyond symptoms and gather other reliable markers of bipolar disorder, such as family history, age of onset, and treatment response. One example is the Bipolarity Index, a 100-point scale that rates how well the patient’s history resembles that of classic bipolar disorder.10 The signs of atypical bipolar are captured on the scale as well, but they are awarded less points. And that’s how it should be: diagnosis is always less certain when there’s something unusual in the presentation.
This article was originally published on 4/5/2018 and has since been updated.
Dr. Aiken is the Director of the Mood Treatment Center, Editor in Chief of The Carlat Psychiatry Report, and Instructor in Clinical Psychiatry at the Wake Forest University School of Medicine. He has served as a subinvestigator on phase-III clinical trials and his research interests include diagnosis of mood disorders, novel pharmacologic agents, and natural and environmental approaches to mental health. He is the coauthor with Jim Phelps, MD, of Bipolar, Not So Much, a self-help book for Bipolar II (W.W. Norton & Co; 2017). He does not accept honoraria from pharmaceutical companies.
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