LOCOMOTOR-ACTIVITY IN DEPRESSED CHILDREN AND ADOLESCENTS .1. CIRCADIAN DYSREGULATION

Objective: To determine whether circadian activity rhythms were altered in pediatric patients with depression. Evidence was sought for a shift in the timing of the rhythm, blunting of circadian amplitude, or emergence of noncircadian periodicities. Method: Locomotor activity was quantified in 57 patients with major depressive mood disorders (mean age 12.4 years) and 16 normal controls (9.9 years). Activity was measured in 5-minute epochs during 72 hours using belt-worn electronic activity monitors. Results: Patients with mood disorders displayed a 15% decrease in the amplitude of their circadian rhythm, and a 52% increase in the magnitude of their twice-daily (hemicircadian) rhythm. No significant difference emerged in the timing of the circadian rhythm. Depressed inpatients and outpatients displayed comparable disturbances, which were most marked in adolescents. Conclusions: Circadian activity rhythms were dysregulated in pediatric patients with major depression. These findings may have etiological and diagnostic significance.