Psychological resilience mediates the protective role of default-mode network functional connectivity against COVID-19 vicarious traumatization

The COVID-19 pandemic significantly increased psychological stress globally due to its rapid spread, lockdowns, and uncertainties. While social media and internet access provided information and social connection, excessive exposure led to vicarious traumatization (VT), characterized by stress, burnout, and decreased well-being, potentially leading to anxiety, depression, and PTSD. Although the association between COVID-19 and VT is established, the neurobiological mechanisms remain largely unknown. Understanding the brain functions affecting VT could identify vulnerable individuals and suggest intervention targets. This study aimed to define functional neural markers of COVID-related VT and investigate the mediating role of psychological resilience in the brain-VT link. Psychological resilience, the ability to adapt positively to adversity, is crucial in determining PTSD development after trauma exposure, and plays a protective role against VT. Previous neuroimaging evidence indicates that stress and stress-related disorders involve brain systems including the limbic regions and prefrontal cortex, parts of the default mode network (DMN). DMN's role in stress and stress-related psychopathology is well-recognized, with altered functional activity and connectivity linked to higher perceived stress, PTSD, mood disorders, and anxiety. Conversely, increased DMN volume and integration are associated with psychological resilience, suggesting a potential mechanism for individual VT variations. The researchers hypothesized that pre-pandemic FCD and RSFC in DMN regions would predict VT levels during the pandemic, and that psychological resilience would mediate the brain-VT associations. This prospective study used pre-pandemic resting-state fMRI (RS-fMRI) data to predict VT during the pandemic in healthy university students.

Existing literature highlights the impact of the COVID-19 pandemic on mental health, with increased psychological stress and the potential for vicarious traumatization (VT) through excessive media exposure. Studies have established a link between COVID-19 and VT, but the underlying neurobiology remains largely unexplored. Neuroimaging research indicates that stress and stress-related disorders involve the limbic regions and prefrontal cortex, components of the default mode network (DMN). Studies show altered DMN activity and connectivity in individuals with higher stress levels, PTSD, and other mood disorders. Conversely, increased DMN volume and integration have been associated with resilience, suggesting a potential mediating role in VT. The protective effect of psychological resilience against VT and other adverse effects of COVID-19 has also been supported in previous research.

This prospective study included 151 healthy, right-handed Chinese university students (100 in final analyses after exclusion criteria). Resting-state fMRI (RS-fMRI) data were collected from October 2019 to January 2020 (T1, pre-pandemic), and participants completed a COVID-19-related online survey (VTQ and CD-RISC) from February to April 2020 (T2, during the pandemic). The Vicarious Traumatization Questionnaire (VTQ) measured VT, and the Connor-Davidson Resilience Scale (CD-RISC) measured psychological resilience at both T1 and T2. Other measures included socioeconomic status (SSS) and stressful life events (SRLEC). RS-fMRI data were preprocessed using DPABI software, including motion correction, normalization, and regression of nuisance covariates. Functional connectivity density (FCD) maps were computed using a threshold of 0.6. Whole-brain FCD-behavior correlation analysis identified brain regions where FCD was related to VT. Resting-state functional connectivity (RSFC) analysis explored the interaction of identified regions with other brain areas and their relationship to VT. Prediction analysis using a four-fold balanced cross-validation with linear regression examined the robustness of the brain-VT link. Mediation analysis with PROCESS macro in SPSS investigated the mediating role of psychological resilience in the brain-VT associations. Large-scale network mapping characterized the identified clusters.

Whole-brain FCD-behavior correlation analysis revealed a significant negative correlation between VT and FCD in the right inferior temporal gyrus (ITG) (r = -0.35, p < 0.001). RSFC analysis using the ITG as a seed showed that VT was negatively associated with functional connectivity between the ITG and other DMN regions, including left medial prefrontal cortex (MPFC), left orbitofrontal cortex (OFC), right superior frontal gyrus (SFG), right inferior parietal lobule (IPL), and bilateral precuneus. Prediction analyses confirmed that FCD in the right ITG and mean ITG-DMN RSFC significantly predicted VT (FCD: [predicted, observed] = 0.33, p < 0.001; RSFC: [predicted, observed] = 0.39, p < 0.001). Mapping onto large-scale networks indicated that the ITG cluster was primarily part of the DMN (52.5%). Psychological resilience was positively correlated with ITG FCD (r = 0.24, p = 0.02) and ITG-DMN connectivity (r = 0.30, p = 0.003). Mediation analyses showed that psychological resilience significantly mediated the relationship between both ITG FCD and ITG-DMN connectivity and VT. The negative association between FCD of the right ITG and VT (c = -0.39, p < 0.001) decreased after including psychological resilience (c’ = -0.33, p < 0.001), with a significant indirect effect (indirect effect = -0.06, 95% CI = [-0.12, -0.01], p < 0.05). Similarly, psychological resilience had a significant mediation effect on the relationship between ITG-DMN connectivity and VT (indirect effect = -0.06, 95% CI [-0.13, -0.01], p < 0.05). These findings remained robust even after controlling for socioeconomic status and stressful life events.

This study's findings provide evidence for the brain's role in COVID-related VT, highlighting the importance of the right ITG and DMN. Decreased FCD in ITG and reduced ITG-DMN connectivity may reflect impaired internally focused thought and empathic engagement, contributing to higher VT. The involvement of the affective network (AFN) and central executive network (CEN) further suggests emotional processing and cognitive control deficits in VT. The significant negative correlation between VT and psychological resilience confirms resilience's protective role against VT symptoms. Critically, this study demonstrates for the first time that psychological resilience mediates the effect of DMN connectivity on VT, suggesting that enhanced coping mechanisms can buffer the impact of traumatic exposure via media.

This study is the first to show the protective effect of DMN functional connectivity against COVID-19 vicarious traumatization through psychological resilience. The right ITG and DMN are potential targets for interventions aimed at preventing and treating stress and trauma-related mental disorders. Non-invasive brain stimulation and psychotherapy focusing on enhancing psychological resilience could reduce VT susceptibility. Future longitudinal studies with repeated assessments and diverse populations are needed to validate these findings and explore other DMN regions' roles in VT.

This study's limitations include the use of pre-pandemic MRI data only, preventing the observation of time-course changes in brain function and VT. Self-reported measures of VT and psychological resilience were used, potentially introducing biases. The sample consisted mainly of university students, limiting generalizability. The study primarily focused on the ITG, with potential involvement of other DMN regions warranting further investigation. The group-level atlas may dilute individual-specific brain-behavior associations. The exploratory nature of the study requires caution in interpreting findings and their clinical applicability.