Ultradian rhythms and temporal coherence in sleep EEG in depressed children and adolescents

Background: It has been suggested that a primary ultradian (80–120 minute) rhythm disturbance in EEG underlies sleep abnormalities in adults with depression. The present study evaluated ultradian rhythm disturbances in childhood and adolescent depression. Methods: Sleep macroarchitecture and temporal coherence in quantitative EEG rhythms were investigated in 50 medication-free outpatients with major depression (25 children and 25 adolescents) and 15 healthy normal controls (5 children and 10 adolescents). Results: Few of the macroarchitectural measures showed significant group effects. In fact, age and sex effects were stronger than disease-dependent components. Temporal coherence of EEG rhythms during sleep did differentiate those with MDD from controls. Both depressed children and adolescents had lower intrahemispheric coherence, whereas interhemispheric was only lower in depressed adolescents in comparison with controls. Gender differences were evident in adolescents, but not children, with MDD with lowest interhemispheric coherence in adolescent girls. Conclusions: These findings are in keeping with increased risk for depression in females beginning at adolescence and extending throughout adulthood. It was suggested that low temporal coherence in depression reflects a disruption in the fundamental basic rest-activity cycle of arousal and organization in the brain that is strongly influenced by gender.