Re-evaluating the prevalence of and diagnostic composition within the broad clinical spectrum of bipolar disorders

Until recently it was believed that no more than 1% of the general populati on has bipolar disorder. Emerging transatlantic data are beginning to provi de converging evidence for a higher prevalence of up to at least 5%. Manic states, even those with mood-incongruent features, as well as mixed (dyspho ric) mania, are now formally included in both ICD-10 and DSM-IV. Mixed stat es occur in an average of 40% of bipolar patients over a lifetime; current evidence supports a broader definition of mixed states consisting of full-b lown mania with two or more concomitant depressive symptoms. The largest in crease in prevalence rates, however, is accounted for by 'softer' clinical expressions of bipolarity situated between the extremes of full-blown bipol ar disorder where the person has at least one manic episode (bipolar I) and strictly defined unipolar major depressive disorder without personal or fa mily history for excited periods. Bipolar II is the prototype for these int ermediary conditions with major depressions and history of spontaneous hypo manic episodes; current evidence indicates that most hypomanias pursue a re current course and that their usual duration is 1-3 days, falling below the arbitrary 4-day cutoff required in DSM-IV. Depressions with antidepressant -associated hypomania (sometimes referred to as bipolar III) also appear, o n the basis of extensive international research neglected by both ICD-IO an d DSM-IV, to belong to the clinical spectrum of bipolar disorders. Broadly defined, the bipolar spectrum in studies conducted during the last decade a ccounts for 30-55% of all major depressions. Rapid-cycling, defined as alte rnation of depressive and excited (at least four per year), more often aris e from a bipolar II than a bipolar I baseline; such cycling does not in the main appear to be a distinct clinical subtype - but rather a transient com plication in 20% in the long-term course of bipolar disorder. Major depress ions superimposed on cyclothymic oscillations represent a more severe varia nt of bipolar IT, often mistaken for borderline or other personality disord ers in the dramatic cluster. Moreover, atypical depressive features with re versed vegetative signs, anxiety states, as well as alcohol and substance a buse comorbidity, is common in these and other bipolar patients. The proper recognition of the entire clinical spectrum of bipolarity behind such 'mas ks' has important implications for psychiatric research and practice. Condi tions which require further investigation include: (1) major depressive epi sodes where hyperthymic traits - lifelong hypomanic features without discre te hypomanic episodes - dominate the intermorbid or premorbid phases; and ( 2) depressive mixed states consisting of few hypomanic symptoms (i.e., raci ng thoughts, sexual arousal) during full-blown major depressive episodes - included in Kraepelin's schema of mixed states, but excluded by DSM-IV. The se do not exhaust all potential diagnostic entities for possible inclusion in the clinical spectrum of bipolar disorders: the present review did not c onsider cyclic, seasonal, irritable-dysphoric or otherwise impulse-ridden, intermittently explosive or agitated psychiatric conditions for which the b ipolar connection is less established. The concept of bipolar spectrum as u sed herein denotes overlapping clinical expressions, without necessarily im plying underlying genetic homogeneity. in the course of the illness of the same patient, one often observes the varied manifestations described above - whether they be formal diagnostic categories or those which have remained outside the official nosology. Some form of life charting of illness with colored graphic representation o f episodes, stressors, and treatments received call be used to document the uniquely varied course characteristic of each patient, thereby greatly enh ancing clinical evaluation. (C) 2000 Elsevier Science BN. All rights reserv ed.