Advanced Reading: Diagnosis of Bipolar Disorder

Abstract and Introduction

Charles L. Bowden, MD

Abstract

Bipolar disorders are currently divided into 4 entities: bipolar I, bipolar II, cyclothymic disorder, and bipolar disorder not otherwise specified, as described in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).^[1] These subtypes of bipolar disorders cover a spectrum of severities, frequencies, and durations of manic and depressive symptoms. The differential diagnosis among these and with regard to other disorders with similar symptom features remains the foundation for treatment of bipolar disorders. It is clear that much diversity exists within these major subtypes, such that designations like "rapid cycling" and "bipolar III" are being put forward and probed for clinical relevance. Some of the concerns and advantages of including these less-established manifestations of bipolar disorders in our diagnostic thinking are discussed here, and the utility and drawbacks of our current diagnostic protocols are considered.

Introduction

There has been increasing recognition that the population of patients with bipolar features to their mood disorders can exhibit a wide variation in the severity of manic and depressive episodes, as well as in the frequency of cycling between such episodes. This has inspired efforts to further characterize subtypes of bipolar disorders and to scrutinize mood disorders generally for links between unipolar and bipolar disease. For example, while most clinical studies of patients with atypical depression (most recent depressive episode with features of mood reactivity/overreactivity to positive events, hyperphagia, hypersomnolence, severe fatigue/leaden paralysis, chronic oversensitivity to rejection) have excluded patients with definite bipolar disorder, many patients who fit this depressive symptomatology indeed have features of bipolar II disorder.^[2] This ongoing probing of variation within well-established mood-disorder entities promises, eventually, to benefit patients through identifying the most effective treatments for each specific subtype. It also aids in evaluating the outcomes of such treatments and offers the hope of discovering prognostic markers. The need for diagnostic, if not academic, distinction between bipolar and other disorders, such as between a manic episode of bipolar I disorder and attention-deficit/hyperactivity disorder (ADHD), is increasing as well. Heightened attention to the latter has generated an increased tendency to medicate children for ADHD that may have outpaced the practitioners' ability to reliably distinguish this disorder from a bipolar condition.

Diagnosis of Bipolar Disorders

Bipolar disorders recognized in the DSM-IV include bipolar I, bipolar II, cyclothymic disorder, and bipolar disorder not otherwise specified. The diagnostic and associated features of these entities are listed in Table 1. A diagnosis of any of these bipolar disorders requires first that the presence of a mood disturbance has been ascertained, and that other causes of the symptoms observed have been ruled out. Most notable among conditions that can confound diagnosis by presenting similar symptoms are mood disorders due to a general medical condition (eg, multiple sclerosis, hypothyroidism) (Table 2) or substance abuse (Table 3). These can be diagnosed as separate entities distinct from bipolar disorders (referred to, respectively, as "mood disorder due to a general medical condition" and "substance-induced mood disorder"), which can, in most cases, be distinguished by patient history and clinical or physical findings. If these other causes are dismissed, diagnosis of a bipolar disorder is next contingent on specifying the duration, quality, and degree of mania-like symptoms. Although not part of the DSM-IV, Akiskal has suggested that the inclusion of a positive family history be a part of diagnosis.^[3] The inclusion of this criterion may be particularly useful in patients with subthreshold disease and mixed states.

Bipolar I disorder is diagnosed when there is a history or current evidence of a "pure manic" or "mixed" episode. A pure manic episode is an abnormally and persistently elevated, expansive, or irritable mood that is accompanied by at least 3 (or 4, if the primary mood is irritable) other symptoms (Table 4). Mixed episodes have features of mania intermixed with symptoms of a major depressive episode that cause significant impairment of functioning and/or require hospitalization. Periods between a manic or a mixed episode may be characterized by major depression with features similar to those seen in unipolar depressive episodes or, instead, by relative euthymia. Bipolar II disorder is diagnosed when episodes of excitement of at least 4 days duration have been or are present, but which are less dramatic than those for mania and do not require hospitalization. A history or current symptoms of major depression must also characterize the patient diagnosed with bipolar II. Periods of hypomania that have not lasted 4 days typically warrant a diagnosis of bipolar not otherwise specified. This diagnosis also is appropriate for patients who have hypomanic symptoms but insufficient depressive symptoms.^[1] And, finally, cyclothymia is the diagnosis of cyclic manic and depressive symptoms that are not of sufficient magnitude or duration to warrant a diagnosis of bipolar I or bipolar II, but have occurred over at least a 2-year period with symptom-free intervals of less than 2 months (Table 5).