Neural Mechanisms Underlying The Impact Of Resilience On Psychosocial Stress-induced Response In Healthy Adults

Objective:Resilience is the individual’s ability to adapt well after adversity and pressure.A large number of behavioral studies have shown that resilience is a protective factor of stress.However,the effect and brain mechanism of resilience on psychosocial stress response are still unclear.In this study,the psychological,physiological and neural imaging characteristics of healthy adults with high and low resilience during stress tasks were comprehensively examined to investigate the influence of resilience on psychosocial stress processing and its underlying mechanism,and provide empirical basis for developing relevant targeted intervention measures.Methods:Connor-Davidson Resilience Scale（CD-RISC）was adopted to measure resilience level,The State-Trait Anxiety Inventory（STAI）and the Beck Depression Inventory（BDI）was adopted to measure the level of anxiety and depression.Cognitive Emotion Regulation Questionnaire（CERQ）was adopted to measure the use of cognitive emotion regulation strategies.According to the CD-RISC scores of 1493college students,the demarcation scores of high resilience group and low resilience group were determined,and the corresponding healthy college students were recruited for the functional Magnetic Resonance Imaging（fMRI）experiment.A total of 115 subjects were enrolled in this study,including 59 in the high resilience group（HR）and 56 in the low resilience group（LR）.Montreal Imaging Stress Task（MIST）was used for the fMRI experiment,and salivary cortisol level and subjective stress level were evaluated at multiple time points before and after the task.The differences in subjective stress level,cortisol response and stress-related brain activation between the two groups were compared.Psych-physiological Interaction（PPI）was used to investigate the characteristics and differences of brain functional connectivity between the two groups.Correlation analysis was carried out between resilience,CERQ scores,cortisol response to stress,changes in subjective stress level,and the brain activities（activations and connectivities）that significantly differed between the two groups.A mediation model was constructed to investigate the mediation effect of resilience and its brain mechanism on individual psychosocial stress response to depression and anxiety.Results:There was no significant difference in demographic data between two groups.Though all within the normal range,the levels of depression and anxiety in LR were significantly higher than those in HR.Repeated measures ANOVA indicated that both groups showed significant increases in cortisol levels and subjective stress after MIST task compared with before stress（p<0.01）.The increase in subjective stress level of the LR was significantly larger than that of the HR（p<0.01）,and the decrease in cortisol level within 30 minutes after MIST task of LR was significantly smaller than that of HR（p<0.01）.For both groups,during the MIST task,the activity of insula,thalamus,middle frontal gyrus,middle occipital gyrus and supramarginal gyrus increased significantly,and the activity of the lenticular nucleus,precuneus,the medial orbital part of superior frontal gyrus（ORBsupermed）and angular gyrus decreased significantly(p _FWE-voxel<0.05).Inter-group comparison of brain activation during the MIST showed that the activation of left anterior insula cortex（AIC）in LR was significantly higher than that in HR（p<0.05）.The results of PPI showed that the functional connectivity between left ORBsupermed and right temporal pole of middle temporal gyrus（TPOmid）in LR was significantly lower than that in HR(p_{uncorrected-voxel}<0.001,p_FWE-cluster<0.05).Correlation analysis results showed that CD-RISC score was negatively related to the levels of depression and anxiety,the use of catastrophizing,the changes in cortisol level before and after stress,and the activation of left AIC（p<0.05）.Meanwhile,it was positively correlated with the scores of positive regulation strategies such as positive refocus,refocusing the plan and positive reappraisal,and the functional connection strength between left ORBsupermed and right TPOmid（p<0.05）.The activation of left AIC was positively correlated with the changes in cortisol level,depression and anxiety scores,and the use of catastrophizing,but negatively with the use of positive reappraisal（p<0.05）.The functional connectivity between left ORBsupermed and right TPOmid was positively correlated with positive reappraisal score（p<0.05）.Mediation model showed that the activation of left AIC partially mediated the relationship between resilience and depression,and the function connectivity between left ORBsupermed and right TPOmid partially mediated the relationship between resilience and anxiety.Conclusion:The brain mechanism related to the effect of resilience on stress in healthy adults mainly involves the activation of left AIC and the functional connectivity between the left ORBsupermed and right TPOmid.The greater activation in left AIC during stress detected in the LR might underlie the neural mechanism of depression accumulation caused by daily psychosocial stress,while the low functional connectivity between the left ORBsupermed and right TPOmid of LR may indicate the neural mechanism of anxiety accumulation.