The Influence Of Negative Events On Social Anxiety And Its Brain Structure And Function Foundation

For a long time,human beings face various challenges in their daily work,study,and other life states.And life events are the synthesis of the stimuli experienced in an individual’s life within a certain period of time,and it is also the basic component unit of life.A large number of studies at home and abroad have shown that negative life events are closely related to anxiety.Social anxiety refers to the negative anxiety that arises when an individual is subjectively afraid of being judged by others due to the embarrassment of self-expression in a social situation.Social anxiety not only refers to subjective feelings of anxiety,but also involves individuals’tendency to stay away from social situations and show social avoidance behaviors.The Social Avoidance and Distress Scale（SAD）consists of two dimensions:social avoidance and social distress.Social distress is a measure of subjective distress,while social avoidance is a measure of behavioral avoidance,which together reflect social anxiety.The brain is the most complex structure in the central nervous system,and it is not only the organ that regulates various body functions,but also the physiological basis for higher neural activities such as cognition,emotion,and behavior.Thanks to MRI technology,more and more researchers have started to examine the neural mechanisms related to negative life events and social anxiety separately in recent years.As an important stressor in later life,the relationship between negative life events and social anxiety has not been mechanistically investigated in studies.Although a small number of behavioral studies have examined the relationship between negative life events and social anxiety,few neural mechanisms have been investigated,and in addition,the effects of structural and functional brain connections related to negative life events on social anxiety have not been considered.In summary,this paper proposes three studies to investigate the relationship between negative life events and social anxiety from behavioral and neural mechanisms perspectives.Study 1 aims to investigate the behavioral relationship between negative life events and social anxiety.Due to the early establishment of the scales,reliability and validation factor analyses were conducted to ensure the reliability and validity of the Adolescent Life Events Scale and the Social Avoidance and Distress Questionnaire.First,we collected negative life event levels and social anxiety levels of 659 subjects at the same time and 6 years later,firstly,we correlated negative life events with social anxiety at cross-sectional time points to determine the relationship,and then we used a mediation model to determine whether subjects’trait anxiety levels could explain the effect of negative life events on social anxiety,and finally,we used a machine learning support vector regression（SVR）method to determine the relationship between negative life events and social anxiety.Vector Regression（SVR）method was used to predict social anxiety at the second time point based on the negative life events at the first time point.The results revealed that 1)the overall consistency of the Adolescent Life Events Scale was 0.952 and the overall consistency of the Social Avoidance and Distress Scale was 0.904.The questionnaire structure of the Adolescent Life Events Scale was fair and that of the Social Avoidance and Distress Scale was good for the performance of this sample.2)The total score of negative life events and each dimension were significantly and positively correlated with the total score of social anxiety at the cross-sectional time（total score r=0.165,p<0.001）.3)The mediation of negative life events on social anxiety based on trait anxiety held.4)Negative life events at the first time point predicted social anxiety performance at the second time point（r=0.319,p<0.05）.The results of this study confirm a stable behavioral relationship between negative life events and social anxiety on a temporal scale.The purpose of Study 2 was to reveal the relationship between negative life events and their brain structure and social anxiety.In this study,data from 697 individual adolescent life events（ASLEC）of college students ranging in age from 16 to 26 years and their two magnetic resonance structural images more than one year apart from school were collected and processed to obtain structural indices of cortical volume,density and surface area for each subject.The whole brain regions were correlated with the life event scale to determine their relationships,and the developmental trends were determined by the amount of brain changes to establish their relationships with life events.Finally,the prediction model of social anxiety by brain structure and change volume was established by SVR.The results showed that 1)the total life event score and its dimensions were positively correlated with the Gray Matter Volume（GMV）of the right middle temporal gyrus（MTG）（r=0.186,p<0.001）.2)The change volume of the gray matter volume of the right middle temporal gyrus（MTG）was negatively correlated with life events（r=-0.151,p<0.01）.3)The gray matter volume of brain regions associated with negative life events（r=0.527,p<0.001）and the amount of change in their gray matter volume（r=0.483,p<0.01）predicted social anxiety.The results suggest that negative life events not only promote early maturation of the middle temporal gyrus,which is closely related to anxiety,but also lead to a slowing of its development,and that its gray matter volume and change amount predict social anxiety.Study 3 aimed to investigate the effects of negative life events and their functional brain connectivity on social anxiety.In this study,662 college subjects were recruited and resting-state functional imaging data were collected.In addition,each subject completed the Adolescent Life Events Scale and the Social Avoidance and Distress Questionnaire.The amygdala and precuneus,which are associated with negative life events,were selected as seed sites according to previous literature,and then seed-based functional connectivity（ROI-Wise）analysis was performed at the level of regions of interest wise（ROI-Wise）.Connectivity)analysis.The results revealed that 1)negative life events were significantly associated with amygdala-precuneus functional connectivity(r=0.092,p_FDR=0.034[X=-4,Y=-58,Z=30];r=0.100,p_FDR=0.027[X=-11.33,Y=-56.51,Z=30.33]).2)The effect of negative life events on social anxiety based on mediated by amygdala-precuneus functional connectivity was established.The results indicated that the functional connections positively associated with social anxiety were mainly found within the default network.These results suggest that social anxiety is associated with functional interactions between brain regions involved in self-referential processing,executive control and emotion regulation,and reward processing during negative emotion processing.In summary,this study explored the relationship and predictive role of adolescent life events and social anxiety at the behavioral level from a longitudinal perspective,and at the neural mechanism level to explore how negative life events affect social anxiety through related brain structures and their changing characteristics,functional brain connectivity,and thus social anxiety.The results of these studies have important implications for exploring the neural mechanisms underlying the relationship between negative life events and social anxiety,for the improvement and regulation of negative emotions in the future,and for improving the mental health of individuals,as well as providing neuroscientific evidence for the development of appropriate intervention methods.