The modifications of the long-range temporal correlations of the sleep EEG due to major depressive episode disappear with the status of remission.
OBJECTIVE
The aim of the present study is to investigate the scaling properties of the sleep electroencephalogram (EEG) in remitted depressed men, and to evaluate if a past history of major depressive disorder (MDD) could modify significantly and definitively, as a "scar marker," the dynamics of the sleep EEG time series.


METHODS
Whole night sleep electroencephalogram signals were recorded in 24 men: 10 untreated depressed men in full to partial remission (42.43+/-5.62 years) and 14 healthy subjects (42.8+/-8.55 years). Scaling properties in these time series were investigated with detrended fluctuation analysis (DFA) (time range: 0.16-2.00 s). The scaling exponent alpha was determined in stage 2, in slow wave sleep (stages 3 and 4), and during rapid eye movement (REM) sleep. Forty-five epochs of 20 s were chosen randomly in each of these stages for each subject in both groups.


RESULTS
We did not observe a significant difference and deviation of the scaling exponents between the two groups during the three sleep stages of interest.


CONCLUSIONS
In this study, we do not observe any functional sequelae of a past history of one or more unipolar major depressive episode on the fluctuation properties of the sleep EEG. This finding is a sign of similar underlying neuronal dynamics in healthy controls and patients with a lifetime history of MDD. This study gives an additional argument to the theory that depression does not modify definitively the dynamics of the neuronal networks and is therefore against the "depressive scar hypothesis," in which permanent residual deficit is created by the acute state of the depressive disease.
Leistedt
S
S
Sleep Laboratory, Department of Psychiatry, Erasme Academic Hospital, Université Libre de Bruxelles, Route de Lennik, 808, 1070 Brussels, Belgium. samuel.leistedt@ulb.ac.be
Dumont
M
M
Coumans
N
N
Lanquart
J-P
JP
Jurysta
F
F
Linkowski
P
P
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D015415:Biomarkers; D002540:Cerebral Cortex / Q000503:physiopathology*; D003866:Depressive Disorder / Q000150:complications* / Q000503:physiopathology*; D004569:Electroencephalography; D006801:Humans; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology; D009474:Neurons / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D012893:Sleep Wake Disorders / Q000209:etiology* / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology; D013995:Time; D013997:Time Factors
D015415:Biomarkers