Similar sleep EEG topography in middle-aged depressed patients and healthy controls.
OBJECTIVE
One of the early hypotheses relating sleep disturbances in depression to a model of sleep regulation is the S-deficiency hypothesis. It is postulated that, in depressed patients, sleep propensity during wakefulness does not rise to the level attained by nondepressed subjects, resulting in altered sleep structure or changes in the electroencephalogram during sleep. We aimed to test this hypothesis by assessing topographic changes in the sleep electroencephalogram associated with depression.


METHODS
Cross-sectional clinical study.


METHODS
Mental Health Clinical Research Center.


METHODS
Sixteen unmedicated depressed outpatients (mean age: 41.2 years) and 16 pair-matched healthy controls (mean age: 41.1 years).


METHODS
None.


METHODS
Baseline sleep electroencephalogram recordings were obtained from a central referential electrode and from 3 bipolar derivations (frontocentral, centroparietal, parietooccipital) along the anteroposterior axis.


RESULTS
Symptoms of depression at the time of sleep recordings were moderate (24-item Hamilton Rating Scale of Depression range: 16-31). No differences between patients and controls were found in sleep variables and all-night electroencephalogram spectra in non-rapid-eye-movement and rapid-eye-movement sleep. The ultradian modulation of slow-wave activity (power within 0.75-4.5 Hz), as well as the exponential decline of slow-wave activity, during sleep did not differ between the groups. The statistical analyses of electroencephalogram power gradients between adjacent derivations revealed no Group x Derivation interactions. An anterior dominance in non-rapid-eye-movement sleep power was present in the 0.75- to 2-Hz range, which diminished throughout the night.


CONCLUSIONS
These findings in moderately depressed patients do not support the existence of an S-deficiency during sleep. Because the build up of sleep propensity during waking can be dissociated from its decline, future studies need to investigate the waking electroencephalogram spectra in depression.
Landolt
Hans-Peter
HP
University of California at San Diego, Department of Psychiatry, VA San Diego Healthcare System, San Diego, California, USA. landolt@pharma.unizh.ch
Gillin
J Christian
JC
D000328:Adult; D001931:Brain Mapping / Q000295:instrumentation*; D003430:Cross-Sectional Studies; D003863:Depression / Q000175:diagnosis / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006304:Health Status; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D012720:Severity of Illness Index; D012894:Sleep Stages / Q000502:physiology; D011795:Surveys and Questionnaires; D013702:Temporal Lobe / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology