The study was conducted by a senior psychiatrist of the Department of Psychiatry, National Health Service, of Forlì in Italy. The author had spent 16 years treating mood disorders, and had research experience.8,10–19 The study was conducted in the author's private practice, because private practice is more representative of mood patients in Italy, where it is the first (or second, after family doctors) line of treatment for mood disorders. Most severe mood patients are usually treated in national psychiatric services or in university centres. Mood patients from academic centres are thought to be not representative of typical mood patients.20
Two hundred and seventeen consecutive Bipolar II outpatients, presenting for major depressive episode (MDE) treatment with minimal or no concurrent psychopharmacology, were included in the study over 2 years. Informed consent was obtained after the procedure was fully explained. Substance abuse and severe personality disorders (diagnosed by clinical interview following DSM-IV criteria) were not included, because they may be confused with Bipolar II.21 Patients had no clinically significant general medical illness. Patients were interviewed during the first visit with the Structured Clinical Interview for DSM-IV Axis I Disorders-Clinician Version, Mood Disorder module (SCID-CV),22 the Montgomery Asberg Depression Rating Scale (MADRS),23 and the Global Assessment of Functioning (GAF) Scale.6 Family members or close friends supplemented clinical information during the interview. The DSM-IV criteria for the diagnosis of Bipolar II disorder are: (a) presence or history of one or more major depressive episodes; (b) presence or history of at least one hypomanic episode; (c) there has never been a manic episode or a mixed episode; (d) the mood symptoms in criteria a and b are not better accounted for by schizoaffective disorder and are not superimposed on schizophrenia, schizophreniform disorder, delusional disorder, or psychotic disorder not otherwise specified; and (e) the symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning. As the modal duration of hypomania is 1–3 days, DSM-IV 4 days minimum duration of hypomania was not followed.21‘At least some days’ of hypomania were required. Most patients had experienced 2–3 days of hypomania, and all had had more than one hypomanic episode. Axis I comorbidity diagnoses were made by SCID-CV interview, when comorbidity was spontaneously reported. The sample was divided in a group with history of more than three MDE (+ 3 MDE), and a group with history of three or fewer MDE (–3 MDE), following Winokur's subdivision of Bipolar I.24,25 The study was a cross-sectional study, and data on number of MDE were based on the patient interview, and on information from family members and close friends. Variables studied were age, gender, first MDE age at onset, duration of illness from onset of the first MDE, number of previous MDE, chronicity (MDE/MDE without full interepisode recovery lasting more than 2 years), atypical and psychotic features, axis I comorbidity, and MDE severity at intake. A T-test for means, a two-sample test of proportions, linear and logistic regression, were used (STATA 5; Stata Corporation, College Station, TX, USA, 1997). The P values were two-tailed, and probability was P < 0.05.