Local inefficiency of the default mode network in young men with narcissistic personality disorder.

Neuroimaging studies have shown structural deficits in the default mode network (DMN) in patients with narcissistic personality disorder (NPD); however, the functional basis of the DMN in NPD remains unclear. This study aimed to explore the functional basis of the DMN in NPD from the perspective of the connectome. Nineteen young male patients with NPD (mean age, 18.47 ± 0.77 years; range, 18-20 years) and 19 young male healthy control (HC) participants (mean age, 19.05 ± 1.31 years; range, 18-22 years) were recruited for resting-state functional magnetic resonance imaging examinations. The DMN architecture was depicted by 20 DMN subregions. Graph theory approaches were applied to investigate the functional topology within the DMN in NPD, and Pearson correlations between network parameters and psychological scores were assessed. The NPD group demonstrated topological anomalies in the DMN indicated by a decrease in the clustering coefficient and local efficiency compared with the HC group. Additionally, the NPD group showed increased nodal clustering and efficiency in the right posterior cingulate cortex. In the NPD group, local efficiency within the DMN was found to be positively correlated with the Narcissistic Personality Inventory score and negatively correlated the Hiding the Self score. The NPD group showed abnormal topology within the DMN, indicating that the functional segregation of the DMN is disturbed in NPD. The destroyed topology of the DMN may represent a functional basis of the pathogenesis of NPD in young adult males and may be related to the increased vulnerability in NPD, including hiding the self.