Spatio-temporal Dynamics Of EEG Features During Sleep In Major Depressive Disorder After Treatment With Escitalopram

Major depressive disorder(MDD)is one of the most common diseases worldwide.MDD patients have been treated mainly with traditional drugs.These traditional drugs have some disadvantages such as weak tolerance,and slow action onset.Compared to other antidepressants,escitalopram is tolerated better,has fewer adverse effects and has a faster onset of action.However,its pharmacological mechanism has not yet been clarified completely.Previous study only analyzed the relationship between escitalopram and sleep from the perspective of time domain.Sleep is a complicated process,and can be divided into different stages both temporally,and spatially,and is related to multiple interactions between different brain regions.However,until now,there have been few studies involving both temporal and spatial dimensions.There are questions still to be resolved,such as whether escitalopram acts the same at each sleep stage,or is specific to certain stages.Also it remains unclear as to whether escitalopram is brain region specific such as the frontal,central,or occipital cortices or displays asymmetries in brain hemispheres.Therefore,it is necessary to explore the pharmacological mechanism underlying the action of escitalopram,and to investigate the relationship between escitalopram and sleep in both temporal and spatial dimensions.In this study,thirteen MDD patients and ten healthy control subjects who completed whole tests were included in the final statistics.Six-channel sleep EEG signals were acquired during sleep.Sleep parameters,power spectrum and nonlinear dynamics were used to analyze the spatio-temporal dynamics features of the sleep EEG after escitalopram treatment.The research work is divided into the following two parts.(1)For temporal dynamics: after escitalopram treatment,there was a significant decrease in sleep onset latency as well as in the duration of the non-rapid eye movement1(NREM1)phase.Sleep structure is close to that of healthy control subjects.Power spectrum distribution showed there was a significant increase in the relative energy of delta1 band,accompanied by a significant decrease in the relative energy of beta2 band.Other sleep stages also showed similar trend,but there was no significant difference.Furthermore,nonlinear dynamic features showed that Lempel-Ziv complexity(LZC)and C0 complexity values were significantly lower.(2)For spatio dynamics: after treatment,the EEG response of the left and right hemisphere showed asymmetry.Further analysis of brain region-specific targets found that the frontal cortex showed a more intense EEG response with escitalopram treatment than central and occipital cortices.These findings may contribute to supply theoretical basis for comprehensive understanding of the pharmacological mechanism of escitalopram in the treatment of depression.