Identification and characterization of greater mood variance in depression

OBJECTIVE: The authors sought to assess the quantity and quality of mood variation in depressed persons. METHOD: Using a visual analogue scale, they compared variation of mood in a group of patients (N = 9) with a DSM-III-R diagnosis of depressive disorder and in a group of nondepressed subjects (N = 9) over 12 consecutive hours. To quantify mood variation for each subject, the authors computed the standard deviation of each subject's 13 mood ratings on the visual analogue scale. To characterize the quality of mood variation within each subject, they plotted each subject's mood ratings as a function of time and applied complex demodulation to confirm cyclical patterns of mood variability (ultradian cycles). RESULTS: The depressed group demonstrated greater mood score variability over the course of the day. Both groups demonstrated ultradian cycles and circadian trends; however, the depressed group demonstrated ultradian cycles of significantly greater amplitude than the nondepressed group. CONCLUSIONS: Repeated assessments of mood at different times of the day may be necessary to obtain an accurate impression of a patient's mood state. Further, the mechanism of depressive disorders may include a deregulation of a normal oscillatory mood variation pattern.