Study On Brain Functional Abnormalities Of Generalized Anxiety Disorder Based On Brain Signal Complexity

Generalized anxiety disorder(GAD)is the most common type of anxiety disorders.It is characterized by persistent nervousness and worry,accompanied by autonomic nervous function excitement and excessive alertness.Although previous researchers have conducted extensive studies on the pathophysiology of GAD from a variety of aspects including behavior,physiology,and psychology,the exact pathophysiology remains not fully elucidated.In recent years,the rapid development and maturation of brain imaging technologies,especially the functional magnetic resonance imaging(fMRI)technology,provide new means for revealing the pathophysiology of GAD.So far,the results of the studies in mental disorders employed traditional imaging indicators based on fMRI technology such as functional connectivity and regional homogeneity(ReHo)are unstable.So it is unable to effectively reveal the pathophysiology of mental disorders.However,the emergence of multiscale entropy(MSE)analysis as a family of non-linear statistics provides new insights into understanding the pathophysiology of mental disorders.In this study,we used temporal and spatial MSE of brain signal to explore the pathophysiology of GAD through rs-fMRI.Two parts of this paper have been put forward:The first part of this work located the abnormal brain regions with altered temporal complexity of brain signal in patients with GAD by means of temporal MSE analysis.Compared with the healthy controls,the increased temporal complexity in patients with GAD was found in the left inferior frontal gyrus,posterior superior temporal sulcus,right anterior cingulate cortex,insula,bilateral superior temporal gyrus,supplementary motor area,and cuneus.However,the temporal complexity in patients with GAD was reduced in some core dysfunctional regions(e.g.,left anterior cingulate cortex,right thalamus,inferior frontal gyrus,inferior temporal gyrus)of anxiety disorders.In addition,there were non-linear relationships between temporal complexity of the aberrant brain regions and anxiety level.By analyzing the brain regions with altered temporal complexity in patients with GAD,we found that these abnormal brain regions are closely related to emotional processing and affective control.This suggests that altered temporal complexity of brain signal could reflect the critical pathological characteristics of GAD,and the complex relationship between temporal complexity and anxiety level provides new insights into understanding the neural dynamics mechanism of brain function systems.In the second part,the spatial MSE analysis method was put forward for the first time in this paper,and was used to detect abnormal spatial complexity of brain signal in patients with GAD.The results showed increased spatial complexity in patients' brain,indicating more chaotic spatial configuration and higher homogeneous brain activities.Furthermore,the altered spatial complexity appeared mainly at scale one,indicating that mental disorder is associated with abnormal pattern of proper spatial scale in the brain.More importantly,an inverted U-shaped relationship was also revealed between spatial complexity and anxiety level,reflecting the important mechanism of neural dynamics.These findings provide new evidence for understanding the pathophysiology of GAD,and indicate that spatial complexity may be an imaging indicators to reflect the abnormal state of the brain.In summary,the current study has two contributions.First,we revealed the alterd temporal complexity of brain signal in patients with GAD,which may reflect the critical pathological characteristics of GAD.second,we innovatively put forward the index of spatial MSE to study the spatial configuration of the brain,and detected higher heterogeneous activities in patients with GAD,revealing the important mechanism of neural dynamics.These findings have also deepened our understanding of the pathophysiology of GAD.