Bipolar II Disorder and Comorbidity Eduard Vieta, Francesc Colom, Anabel Martı ´nez-Ara ´n, Antonio Benabarre, Maria Reinares, and Cristo ´bal Gasto ´ The validity and reliability of the diagnosis of bipolar II disorder has been questioned by means of comorbid- ity with nonaffective disorders, including substance abuse, personality disorders, and anxiety disorders. This study examined the comorbid diagnosis of a sample of bipolar II patients, comparing patients with comorbidity and those with ‘‘pure’’ bipolar II disorder. Forty Research Diagnostic Criteria (RDC) bipolar II patients were assessed by means of the Schedule for Affective Disorders and Schizophrenia, Lifetime Ver- sion (SADS-L) and Structured Clinical Interview for DSM-III-R axis I (SCID-II) for personality disorders. Patients fulfilling RDC criteria for any psychiatric disor- der (except personality disorders) or DSM-IV criteria for any personality disorder w ere compared w ith patients without comorbidity. For practical reasons, cyclothymia was not considered as a comorbid diagno- sis. Half of the sample had lifetime comorbidity with other psychiatric disorders, mainly personality disor- ders (33%), substance abuse or dependence (21%), and anxiety disorders (8%). How ever, only the rates of suicidal ideation (74% v 24%, chi square [ 2 ]  9.03, P  .003) and suicide attempts (45% v 5%,  2  8.53, P  .003) w ere significantly different between pa- tients with and without comorbidity. In summary, although the rates of comorbidity are relatively high in bipolar II disorder, most clinical and course variables are strikingly similar in patients with and without comorbidity except for suicidal behavior, suggesting that comorbidity does not reduce the validity of the diagnosis of bipolar II disorder. Copyright  2000 by W.B. Saunders Company I N RECENT YEARS, bipolar II disorder has acquired increasing diagnostic importance and has been officially recognized as a valid category in DSM-IV. Reported differences between bipolar II and the other two adjacent categories, bipolar I and unipolar depression, include genetic, biological, clinical, and pharmacologic aspects. 1-4 However, since a high rate of psychiatric comorbidity has been reported in bipolar II patients, 5,6 some authors have argued against the true specificity of this diagnosis when comorbidity is excluded. 7 Hence, Cooke et al. 7 were unable to find any clinical differences between bipolar I and II patients in a selected sample of substance abuse and personality disorder–free bipolar patients, concluding that the exclusion of characterologic comorbidity and sub- stance abuse may eliminate some of the differences between bipolar II and other types of affective disorder. Comorbidity would therefore reduce the validity of the diagnosis of bipolar II disorder by rendering the bipolar I and II distinction unneces- sary, provided there is an accurate assessment of substance use and personality issues. On the other hand, Andreasen et al. 8 suggested that, in attending to several clinical validators, the bipolar distinction should take precedence over the primary versus secondary diagnostic distinction, and that within bipolars there is little value in further subtyping into primary versus secondary. Rates of lifetime comorbidity are higher than 50% in bipolar I patients, 9 and higher than 60% in bipolar II. 4 Substance abuse, 10 anxiety disorders, 11 eating disorders, 12 personality disorders, 13 and sev- eral more psychiatric disorders have been reported to be overrepresented in bipolar patients, particu- larly in bipolar II. In an attempt to ascertain the influence of comorbidity in several clinical vari- ables of bipolar II patients, we studied a sample of these patients and compared the patients with psychiatric comorbidity and those with ‘‘pure’’ bipolar II disorder. M ETHOD Forty consecutive outpatients fulfilling Research Diagnostic Criteria (RDC) criteria for bipolar II disorder (depressive disorder with hypomania) were recruited from a primary care psychiatric setting in the city of Barcelona (Spain). This center serves a catchment area of 150,000 inhabitants in the western part of the city. The region consists mainly of middle class inhabitants. After a complete description of the study to the subjects, written informed consent for the collection of clinical and personality data was obtained. All patients were assessed with the Schedule for Affective Disorders and Schizophrenia, Lifetime Version (SADS-L) 14 by two independent raters conduct- ing entirely separate interviews in a 24- to 48-hour interval, and were entered only when concordance for a bipolar II disorder diagnosis was present. The analysis of diagnostic concordance resulted in a  index of 0.89, because in five patients, one of the From the Bipolar Disorders Program, Department of Psychia- try, Hospital Clinic, University of Barcelona, Barcelona, Spain. Supported in part by Grants No. 98/0700 and 028/97 from the Instituto de Salud Carlos III-Fondos para la Investigacio ´n Sanitaria and the Fundacio ´ Marato ´ de TV3, respectively. Address reprint requests to Eduard Vieta, M.D., Ph.D., Department of Psychiatry, Hospital Clinic, Villarroel 170, 08036 Barcelona, Spain. Copyright  2000 by W.B. Saunders Company 0010-440X/00/4105-0008$10.00/0 doi:10.1053/comp.2000.9011 Comprehensive Psychiatry, Vol. 41, No. 5 (September/October), 2000: pp 339-343 339