S Leistedt1, M Dumont, J-P Lanquart, F Jurysta, P Linkowski. 1. Sleep Laboratory, Department of Psychiatry, Erasme Academic Hospital, Free University of Brussels, Route de Lennik 808, 1070 Brussels, Belgium. samuel.leistedt@ulb.ac.be
Abstract
OBJECTIVE: The aim of the present paper is to study the fluctuations of the sleep EEG over various time scales during a specific pathological condition: major depressive episode. Focus is made on scaling behaviour, which is the signature of the absence of characteristic time scale, and the presence of long-range correlations associated to physiological constancy preservation, variability reduction and mostly adaptability. METHODS: Whole night sleep electroencephalogram signals were recorded in 24 men: 10 untreated patients with a major depressive episode (41.70+/-8.11 years) and 14 healthy subjects (42.43+/-5.67 years). Scaling in these time series was investigated with detrended fluctuation analysis (time range: 0.16-2.00s). Scaling exponents (alpha) were determined in stage 2, slow wave sleep (stages 3 and 4) and during REM sleep. Forty-five epochs of 20s were chosen randomly in each of these stages. RESULTS: The median values of alpha were lower in patients during stage 2 and SWS. CONCLUSIONS: Major depressive episodes are characterized by a modification in the correlation structure of the sleep EEG time series. The finding which shows decreasing rate of the temporal correlations being different within the two groups in stage 2 and SWS provides an electrophysiologic argument that the underlying neuronal dynamics are modified during acute depression. SIGNIFICANCE: The observed modifications in scaling behaviour in acutely depressed patients could be an explanation of the sleep fragmentation and instability found during major depressive episode.
OBJECTIVE: The aim of the present paper is to study the fluctuations of the sleep EEG over various time scales during a specific pathological condition: major depressive episode. Focus is made on scaling behaviour, which is the signature of the absence of characteristic time scale, and the presence of long-range correlations associated to physiological constancy preservation, variability reduction and mostly adaptability. METHODS: Whole night sleep electroencephalogram signals were recorded in 24 men: 10 untreated patients with a major depressive episode (41.70+/-8.11 years) and 14 healthy subjects (42.43+/-5.67 years). Scaling in these time series was investigated with detrended fluctuation analysis (time range: 0.16-2.00s). Scaling exponents (alpha) were determined in stage 2, slow wave sleep (stages 3 and 4) and during REM sleep. Forty-five epochs of 20s were chosen randomly in each of these stages. RESULTS: The median values of alpha were lower in patients during stage 2 and SWS. CONCLUSIONS: Major depressive episodes are characterized by a modification in the correlation structure of the sleep EEG time series. The finding which shows decreasing rate of the temporal correlations being different within the two groups in stage 2 and SWS provides an electrophysiologic argument that the underlying neuronal dynamics are modified during acute depression. SIGNIFICANCE: The observed modifications in scaling behaviour in acutely depressedpatients could be an explanation of the sleep fragmentation and instability found during major depressive episode.
Authors: Sara Mariani; Ana F T Borges; Teresa Henriques; Robert J Thomas; Samuel J Leistedt; Paul Linkowski; Jean-Pol Lanquart; Ary L Goldberger; Madalena D Costa Journal: Conf Proc IEEE Eng Med Biol Soc Date: 2016-08