Mood problems can occur before puberty, with the prevalence more than doubling during and after puberty. Some of the mood problems will follow a bipolar course. The challenge is recognizing which patients have unipolar depression, and which are some form of bipolar disorder (BD).
Four variants of BD recognized in ICD and DSM:
1) BD-I requires at least one manic episode to establish the diagnosis; depressive and hypomanic episodes are optional from a diagnostic point of view, even though clinically they are the more common presentations.
2) BD-II requires a history of at least one major depressive episode and one hypomanic episode; the depressive episode is far more likely to come to clinical attention.
3) Cyclothymic disorder requires a year or more of hypomanic/manic symptoms and depressive or dysthymic symptoms, not rising to the level of full blown mania (otherwise the diagnosis is bipolar I) or major depression (which indicates bipolar II).
4) Other specified bipolar and related disorders are diagnosed by exclusion of the previous three. The diagnosis can include cases with hypomania in the absence of major depression, insufficient duration of episode, not quite enough symptoms to meet the formal definition, and brief (eg, approximately 6 months) cyclothymic presentations. Clinically, 2- or 3-day hypomanias are common, and do not appear to differ meaningfully from full-duration hypomania. Episodic presentation of symptoms is more suggestive of mood disorder than more chronic histories of the same symptoms.
Conducting the differential diagnosis
People are unlikely to seek help when hypomanic, and much more likely to seek services when depressed than when hypomanic. Thus, one major differential diagnosis is unipolar depression versus bipolar depression. Both depression and hypomania are associated with episodic irritable mood, especially in youths, so another set of differential diagnoses is BD versus disruptive behavior disorders, disruptive mood dysregulation disorder (DMDD) or ADHD. Note that the DMDD phenotype is common among youth with all BD subtypes; as such, identifying a discrete, episodic BD phenotype does not preclude a comorbid DMDD phenotype and vice versa.
Irritability is also pronounced in anxiety disorders and trauma. Cognitive debiasing strategies—including making multiple diagnostic hypotheses, forcing them to compete, and asking about lifetime history of hypomania and mania whenever treating for mood problems—improve the speed and accuracy of detection. More episodic changes that include discrete exacerbations of irritability, energy, and attention problems make the presentation more suggestive of a mood disorder than differential diagnoses with more chronic presentations.
Dr Goldstein is Director, Centre for Youth Bipolar Disorder, Sunnybrook Health Science Centre; Professor, Departments of Psychiatry and Pharmacology, University of Toronto Faculty of Medicine. Dr Birmaher is Director, Child-Adolescent Bipolar Spectrum Services, University of Pittsburgh Medical Center; Distinguished Professor of Psychiatry, University of Pittsburgh School of Medicine. Dr Youngstrom is Professor, Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill. Drs Goldstein and Youngstrom report no conflicts of interest concerning the subject matter of this article; Dr Birmaher reports that he receives royalties from Random House, UpToDate, and Lippincott, Williams, and Wilkins.
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