Bipolar II Disorder: Frequent, Valid, and Reliable

Abstract

The inclusion of bipolar II disorder as a subtype of bipolar illness in the DSM-IV is probably, from a clinical perspective, the most important change in the classification of mental disorders over the past 25 years. The recognition of this condition as a specific mental disorder has enhanced health care access, medical awareness, and research on a medical entity that had been neglected for ages in the official taxonomies. Clinicians were totally aware of this challenging group of patients who had some sort of apparently milder form of manic-depressive illness but who were burdened with frequent recurrences, lack of evidence-based treatments, and high rates of disability. Unfortunately, only in 1994 was this group of patients given a diagnostic status, with official blessing from the DSM. Some of the difficulties that academic centers, taxonomists, and researchers have had with this condition are exemplified in the article by Malhi et al. While it is true that, originally, the description of what we know today as bipolar II disorder was focused on hospitalized depressed patients with a history of hypomania, we know now that most bipolar II patients are never hospitalized but have very frequent depressive and hypomanic episodes that carry enormous morbidity and mortality. The difference between mania and hypomania is based on not only duration of symptoms but also severity and disability. Malhi et al. insist on the little relevance of the distinction between bipolar I and bipolar II disorder (which might be true for a subset of severe bipolar II patients), but they forget to mention that the actual relevance of defining bipolar II disorder lies in the distinction between this condition and major depressive disorder. Hence, while hypomania can be sometimes (but only sometimes) enjoyable and not particularly disturbing, it is possibly the best predictor of a shortly emerging depressive relapse (indicating the need of maintenance therapy with mood stabilizers) and also a strong indicator of poor response to antidepressants. Hence, for many patients with bipolar II disorder for whom depression is the main source of burden, the identification of hypomanias during the course of illness is critical to develop a treatment plan that includes, as options, mood stabilizers such as lithium or lamotrigine over antidepressants. In reality, most hypomanias carry an unequivocal change in functioning that is uncharacteristic of the individual when not symptomatic, as defined in the DSM-5. The DSM-5 field trials showed that both bipolar I disorder and bipolar II have good reliability. Interestingly, this was not the case for several other conditions that have been much less the focus of controversy, such as major depression and generalized anxiety disorder. As regards to personality disorders, the symptoms of bipolar II disorder are different from those of borderline personality (e.g., hypomania is not part of the definition of borderline personality disorder), and what really needs urgent improvement is the diagnosis and classification of personality disorders in the DSM. A diagnosis of a personality disorder should not be made during an untreated mood episode unless the lifetime history supports the presence of a personality disorder, which can be comorbid with an affective disorder. The arguments as regards to industry promoting the diagnosis of bipolar II disorder make little sense; in fact, for pharmaceutical companies, it would be much better from a business perspective to merge all bipolar disorders into one, making no distinctions between subtypes and saving money from costly clinical trials. The arguments against a point of rarity in the distinction between bipolar I and bipolar II disorders are well taken, but they actually apply to all the