Locomotor activity in depressed children and adolescents: I. 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.