Classifying Depression

To the Editor: Dr. Parker reported that bipolar depression is melancholic. Bipolar I and II may be distinct disorders (1, 2). The prevalence of melancholic features may be low in bipolar II outpatients with depression (3), a common (30%–50% of depressed outpatients) and often atypical depression (4, 5). Bipolar II depression in outpatients may be different from the bipolar I depression, primarily in inpatients, studied by Dr. Parker.

Sixty-four consecutive outpatients with unipolar disorders (major depressive disorder or dysthymic disorder) and 97 consecutive outpatients with bipolar II disorder who were seen for treatment of a major depressive episode in a private practice were interviewed at intake with the Structured Clinical Interview for DSM-IV Axis I Disorders—Clinician Version (6). Because the modal duration of hypomania is 1–3 days (7), the 4-day minimum duration of hypomania found in DSM-IV was not a criterion. “At least some days” of hypomania were required in the bipolar outpatients (5). Most bipolar II subjects had experienced 2–3 days of hypomania, and all had had more than one episode of hypomania. Family members or close friends supplemented clinical information. After complete description of study to the subjects, written informed consent was obtained.

Melancholic features were present in 20 of the bipolar II subjects (20.6%) and in 16 of the unipolar subjects (25.0%) (χ²=0.42, df=1, p=0.51, two-tailed). Atypical features were present in 44 of the bipolar II subjects (45.4%) and in 11 of the unipolar subjects (17.2%) (χ²=13.60, df=1, p=0.0002, two-tailed). These findings are in line with those from previous reports (4, 7–10). Outpatient bipolar II depression seems more atypical, not more melancholic, than unipolar depression. Bipolar I and II depressions may have different clinical pictures in different settings.