The Neural Basis Of Stress Life Event And Neuroticism Influence On Anxiety

Anxiety is a common adaptive behavior, and is not the same as fear, which is felt about something realistically intimidating or dangerous and is an appropriate response to a perceived threat. Excessive anxiety is maladaptive. It is often considered to be the major component of unhealthy lifestyle that contributes significantly to the pathogenesis of not only psychiatric but also many other systemic disorders,such as PTSD, phobia and depression. Although there is an emerging effort to understand the neural impact of adulthood exposure to psychological trauma in nonclinical individuals, less attention has been paid to the long-term effects of adolescence trauma exposure in nonclinical sample. This is of particular interest, as adolescence is a critical period in brain development.In particular, stressful life events have been reported to increase risk for psychopathology, substance abuse and physical diseases. Neuroticism is believed to reflect a stable disposition involving specific biological and psychological mechanisms that produce its robust association with psychopathology. We felt that an insightful analysis of the basis of N would help to better understand the N construct and provide tools for theoretical advancements regarding the association between N and common mental disorders.Study1investigated the neural basis of actue stress trauma using the VBM and MVPA method. The results of Experiment1is that the gray matter density of dACC, rACC, dmPFC and Amygdala of trauma exposed group is a significant larger than control group, the gray matter density of dACC was negatively correlation with anxiety level of individual. The results indicated that the gray matter density may be changed by the trauma exposure within periods as a long as three years. Then, we used the MVPA method to distinguish between the two groups at an individual level. The results revealed patterns of neuroanatomical alterations that could be used to inform the identification of trauma survivors and control at the individual level. In the experiment2, we used the resting state functional connectivity to examine the spontaneous neural activities of trauma-exposed healthy individuals compared with healthy controls matched on age, sex, and education. We observed decreased amygdala-vmPFC and increased amygdala-hippocampus functional connectivity in the trauma survivors compared to healthy controls, and the positive correlation between strength connection and the current subjective distress in the trauma survivors. Our findings provide further evidence of trauma exposure plays a causal role in changes to brain function in health adult populations.Study2investigted the neural basis of charitable donationin non-PTSD survivors of the Sichuan earthquake. Results showed that activations in the striatum of trauma survivors were reduced in both the low donation and the high donation conditions compared with the healthy controls. Furthermore, the trauma survivors also exhibited less activity in the insula than the healthy controls in the high donation condition. Thesefindings suggest that abnormal reward-related activations might be associated with dysfunctions in the reward pathway of trauma survivors. Also, we discuss the possibility that traumatic experiences attenuate the reactivity of reward-related brain areas to positive emotions (as induced by advantageous donations).Study3investigated the life event impact on the brain structure and the function of brain network of adolenscents. In the experiment4, the results indicated that the score of life event was positively with the somatic complaints, trait anxiety and neuroticism. The behavior results showed that the stress life event may increase the risk for somatic complaints or anxiety. The MVPA results showed that the volume of junction of frontal and parietal (primary perceptual cortex), TPJ, amygdale and dlPFC may be sensitivity with the stress life event. We found that the gray matter volume of frontal and parietal was positively correlation with anxiety level of individual. In the experiment5, we used the group ICA to analysis the relationship between the brain network and stress life event at the individual level, we found that the left excutive cognitive network (left frontal parietal network) have a significant correlation with life event at the individual level. Based on the results of structural and functional connectivity, we indicated that the frontal parietal network may be sensitivity to the stress or life event, may be a neurobiological marker of anxiety in adolescent.Study4investigated the relationship between the structure/brain functional network and the subscale of neuroticism. In the experiment4, we used the MVPA method to investigate whether the subscale’s score of neuroticism can be predicted by brian functional network. The results showed that the anterior DMN have a statistically significant accuracy to predictive the self-consciousness of Neuroticism; the posterior DMN have a statistically significant accuracy to predictive the anger and hostility of Neuroticism; salience network can predictive the anxiety, impulsive and anger of Neuroticism. In the experiment5, we found a significant positive correlation between anxiety (somatic complaints) and parahippocampal gyrus (PHG) volume adjacent to the entorhinal cortex. Further analysis revealed that the interaction between PHG volume/entorhinal cortex and neuroticism-anxiety (N-Anx) predicted somatic complaints. Specifically, somatic complaints were associated with higher N-Anx for individuals with increased PHG volume. These findings suggest that increased PHG volume and higher trait anxiety can predict vulnerability to anxiety in the general population.In summy, this study found that both the extreme stress or daily life events will be affect on brain structure and function of normal healthy individuals, and the abnormal structure or function of these regions are correlation wih anxiety level of individual. Such as the wenchuan earthquake, the brain structure or functional connectivity were impacted related to emotion regulation ability and emotional responses, such as prefrontal cortex, hippocampus and the amygdala region. However, the daily stress life events mainly concentrated in the cortex of sense perception, cognitive control, working memory, and attention related with left/right dorsolateral prefrontal cortex, the temporoparietal association cortices, and the frontal joint cortex etc. In addition, this study may be the first study to examine the subscale of Neuroticism, we found that different networks have different effects for the various dimensions of N, so subscale of N may be have different contribution to anxiety. We also found that the anxiety (subscale of Neuroticism) and the the volume of the parahippocampal gyrus have an interaction effect to predict individual’s level of anxiety. So this results may provide that the neurobiological marker of the onset of adolescent anxiety. In future study, we should examine the relationship between the stress life event, personality, brain structure/function and anxiety, build model may be an effective way to dicuss the neural basis of anxiety.