Core Brain Network Connectivity Patterns In Generalized Anxiety Disorder

Generalized Anxiety Disorder(GAD)is a common chronic disease,which belongs to one kind of anxiety disorders.In addition to constant worry and anxiety,patients may experience fear and avoidance of daily activities along with somatic symptoms such as insomnia,headache,muscle tension,nausea,dry mouth,depression,fatigue,and poor concentration.Due to the high lifetime comorbidity rate,GAD is difficult to treat,so it brings a huge economic burden to patients.However,the studies on the directed and structural connectivity of GAD core brain network are still relatively few,and the neuropathological mechanism is still not fully clear.Based on previous brain imaging studies,GAD is considered to be a disorder with abnormal brain connectivity.From the perspective of brain connectivity,exploring the pathological basis of GAD may be an important breakthrough point.Therefore,the aim of this study is to investigate the functional and structural aspects of directed connectivity and fractional anisotropy in patients with GAD,respectively,in order to explore the neural mechanism among the GAD networks.The research content of this paper mainly includes the following two parts:1.Aiming at the problem that anxiety symptoms cause specific changes of restingstate core brain network in patients with generalized anxiety disorder(GAD),this paper analyzed the core default network(c DN),dorsal attention network(DAN)and salience network(SN),which are frequently abnormal in mental disorders,using directed connectionspectrum dynamic causal model and group-level analysis-parameter estimation Bayesian model.At the same time,support vector machine regression model was used to explore the predictive ability of abnormal brain connectivity on clinical anxiety scores.In our study,we found that the anti-correlation relationship was disrupted in GAD patients,that is,the inhibition of c DN to DAN was reduced and switched to excitation; The switching of the inner and outer networks was abnormal,that is,SN inhibition of DAN was increased,but SN inhibition of c DN was decreased,and overall SN afferents were also shown as decreased inhibition.In terms of hierarchical structure,we found a widening gap between the SN and the DAN and DMN,which may lead to a decrease in the difference between whole-brain functional integration.In addition,we found that from DAN to c DN connectivity was associated with clinical anxiety symptoms,and both DAN-c DN connectivity and from DAN to c DN connectivity were associated with somatic anxiety symptoms,and abnormal brain connectivity in GAD patients could predict clinical anxiety scores.This study further clarified the important role of the connectivity pattern of the three networks in the changes of brain function in GAD patients,and may provide a more effective neuroimaging biomarker for GAD to deepen our understanding of the disease.2.To address the specific changes of brain structural network connectivity in GAD patients,the diffusion data were analyzed,and fractional anisotropy(fractional anisotropy)was used to indirectly describe the white matter microstructure and fiber microstructure integrity among the core default network(c DN),dorsal attention network(DAN)and salience network(SN),and the topological properties were used to further investigate their structural connectivity patterns.The results of the study found that GAD patients showed reduced fractional anisotropy in white matter microstructure in all three networks,indicating abnormal white matter microstructure.Meanwhile,the superior longitudinal fasciculus,inferior fronto-occipital fasciculus and uncinate fasciculus contained in the network are related to emotional information processing,attention and visual stimulation.Therefore,the reduction of white matter integrity may be related to the loss of related functions,suggesting that patients with GAD have abnormalities in self-processing,attention and attention mode switching.In addition,it was found that the white matter microstructural abnormalities between SN and DAN were correlated with the number of episodes of patients,which may mean that the more episodes of SN,the more severe the white matter loss.In addition,in terms of topological properties,the global efficiency,local efficiency and clustering coefficient of the three networks in GAD patients were all increased,indicating that the degree of functional integration and transmission capacity are abnormal.Excessive network activity may affect the ability to regulate with other regions,leading to excessive attention and amplification of self-emotion.This study reveals the structural abnormalities of white matter in GAD patients,illustrates the important role of the anticorrelation network in the pathological mechanism of anxiety disorders,and provides a new perspective for understanding the disorders of GAD patients.