Summer mood in winter depressives: validation of a structured interview

Two structured interviews, the Hypomania Interview Guide (Including Hyperthymia), for Seasonal Affective Disorder (HIGH-SAD) and its successor, the Hypomania Interview Guide (Including Hyperthymia), Retrospective Assessment Version (HIGH-R), were validated for the assessment of nondepressed spring/summer mood states in patients with DSM-III-R or DSM-IV diagnoses of Recurrent Bipolar disorder (I, II or NOS) or Recurrent Major Depressive Disorder (MDD; unipolar), both with Seasonal Pattern, and in normal control subjects (HIGH-SAD only). The instruments retrospectively rate the frequency and severity of DSM diagnostic criterion features as well as several non-DSM features. Both instruments had high internal consistency. Normal controls had lower total scores than unipolar patients, who had lower scores than bipolar patients. Total score classified 85-91% of patients with seasonal affective disorder (SAD) into the correct unipolar or bipolar group. For boundary mood cases, small subsets of features provided better classification accuracy. Based on total score, MDD patients were divided into three subgroups: euthymes (normal mood), hyperthymes (slightly elevated mood), and high-hyperthymes (scores overlapping with hypomania). With the exception of sharpened thinking, DSM items dominated patient classifications. Distinct clusters of "positive" (pleasant, agreeable) or "negative" (impairing) features described the mood states. The HIGH-R and HIGH-SAD are useful for discriminating and classifying hypomania and mania in bipolar patients, and euthymia and hyperthymia in unipolar patients.