The resting-state brain activity and connectivity mediates the effect of overt narcissism on negative physical self

Overt narcissism is a stable personality trait in which individuals maintain a relatively positive self-image through self-improvement. Previous studies have suggested that examining the neurobiological processes behind personality could help to understand the mechanism by which the personality acts as a risk or protective factor. However, there is a lack of research investigating the neural mechanisms underlying the influence of overt narcissism on negative physical self (NPS). This study evaluated the resting state brain activity (fractional amplitude of low-frequency fluctuations, fALFF) and connectivity (functional connectivity, FC) of 1647 college students. Whole brain correlation analysis showed that overt narcissism was positively correlated with fALFF in the left insula, left precentral gyrus (PreCG) and bilateral superior temporal gyrus (STG). Moreover, overt narcissism exhibited a significant positive correlation with the right STG-PreCG connectivity, and also was significantly positively correlated with FC between the left STG and posterior cingulate gyrus, the left orbitofrontal cortex, the right inferior frontal gyrus and the right thalamus. The results of mediating analysis showed that fALFF in the left PreCG and the right STG-PreCG connectivity partially mediated the effects of overt narcissism on general and facial appearance of NPS, respectively. This study constructed a model (i.e., overt narcissism→brain regions/FC→NPS), providing neurobiological evidence for the relationship between overt narcissism and NPS.