A Study Of Dynamic Brain Networks In Generalized Anxiety Disorder And Panic Disorder

Anxiety disorders(AD)are a group of mental disorders with excessive fear,anxiety and related behavioral abnormalities as the main performance,which have a great impact on the social function and quality of life of patients,and bring a huge burden to the family and society(Grupp h,Koenig HH,& A,2014).Among them,generalized anxiety disorder(GAD)and panic disorder(PD)are the two most common anxiety disorders,but their pathophysiological mechanism and disease-specific changes are still unknown.With the development of neuroimaging technology,we can study the dynamic changes of human brain activity in a shorter time scale.In order to compare the neurophysiological and pathological characteristics of GAD and PD,the amplitude of low frequency fluctuation(ALFF)and dynamic functional connectivity(DFC)analysis method were used to study the overall activity synchronization of local brain regions and the statistical dependence of functional activities in whole brain,and thus to help further explore diagnostic markers of anxiety disorders.As a case-control design,74 subjects were recruited in this study,including 26 in GAD group,22 in PD group and 26 in health control(HC)group.Demographic data,clinical scale data and resting state MRI data were collected.In Study 1,ALFF was used to compare the regional spontaneous brain activity among GAD group,PD group and HC group.Based on Study 1,group independent components analysis(GICA)and sliding window approach were used in Study 2 to compare the functional connectivity among 8 resting brain networks.The two studies provide some clues for elucidating the pathogenesis of anxiety disorder by comparing the temporal changes of spontaneous brain activity in GAD group,PD group and HC group.The main results are as follows:(1)The results of variance analysis of ALFF values in GAD group,PD group and HC group showed that there were significant differences in frontal lobe,temporal lobe,parietal lobe,occipital lobe and some subcortical regions among the three groups.Compared with the control group,patients with GAD and PD showed increased ALFF values in left middle frontal gyrus,caudate nucleus and right frontal eye movement area,while decreased ALFF values in primary visual cortex,left somatosensory cortex and left posterior cingulate cortex.Compared with PD,the ALFF value of GAD patients increased only in the right angular gyrus,and no significant difference was found in other brain regions.(2)The results of dynamic functional connectivity analysis showed that after ICA processing,42 ICs were selected,which were divided into 8 functional brain networks: basal ganglia,auditory(AUD),visual(VIS),sensorimotor(SM),executive control(EC),default mode(DM),salience(SA)and precuneus networks.Two different connectivity "states" were demonstrated across the whole group: a more segregated state I,which shows the connection strength between networks is weak as a whole(the number of windows accounts for 78% of the total number of windows);a strongly integrated state II,which shows the connection strength between networks is stronger(the number of windows accounts for 22% of the total number of windows).According to the analysis of temporal properties of DFC,there were significant differences in fractional windows and mean dwell time between AD group and HC group(p < 0.05,two-sample T-test).Besides,number of transitions had significant difference between GAD group and HC group(p < 0.05,two-sample T-test).However,there was no significant difference in these temporal properties between GAD group and PD group.In addition,the analysis of dynamic strength shows that functional connections related to anxiety disorder mostly exist in default mode network(DMN),executive control network(ECN)and salience network(SAN),especially between SAN and DMN.Likewise,there was no significant difference between GAD group and PD group in strength of dynamics states.Therefore,this study draws the following conclusions:(1)There were wide-range differences in ALFF values among the three groups.Different brain regions involved DMN,ECN,SAN,BG,SMN,AUD and VIS.(2)Patients with anxiety disorder can be distinguished from healthy controls according to the changes of DFC in resting state.In addition,GAD group may be more sensitive to these time-varying characteristics than PD group,which needs further study.(3)The abnormal functional connections related to anxiety disorder mostly exist in DMN,ECN and San networks,especially between SAN and DMN networks,which may help to explain the abnormal emotional and cognitive functions of AD patients.