Gray matter density of the dorsomedial prefrontal cortex mediates the relationship between catastrophizing and anxiety in somatic symptom disorder

Objective: Catastrophizing is commonly co-occurrence with anxiety in somatic symptom disorder (SSD). However, the quantitative relationship between catastrophizing and anxiety in SSD and its underlying neuropsychopathology remains unclear. Methods: To address the issue, twenty-eight SSD patients and twenty-nine healthy controls (HCs) completed the Hamilton anxiety scale and the catastrophizing subscale of the cognitive emotion regulation questionnaire. Then they underwent structural magnetic resonance imaging and voxel-based morphometry analysis was performed to obtain gray matter density (GMD) of the dorsomedial prefrontal cortex (dmPFC). Results: Independent samples t-tests showed no significance between SSD patients and HCs in the scores on the catastrophizing subscale and GMD of the dmPFC. However, correlation analysis found that catastrophizing was significantly positively associated with anxiety in SSD. Further, mediation analyses revealed that GMD of the dmPFC (bilateral medial Brodmann area 8) mediated the relationship between catastrophizing and anxiety in SSD. Conclusion: These findings support Kirmayer’s disease model of SSD that catastrophic interpretations of somatic symptoms resulted in increased anxiety and demonstrate that the dmPFC may be a potential neural site linking catastrophizing and anxiety in SSD.