Functional brain network topology in parents who lost their only child in China: Post-traumatic stress disorder and sex effects.

<bold>Background: </bold>Post-traumatic stress disorder (PTSD) is associated with disruption of the brain network topology; however, little is known about the topological changes and sex effects in PTSD patients following a unique trauma, the loss of an only child, in China.<bold>Methods: </bold>Fifty-one lost-only-child parents with PTSD, 93 lost-only-child non-PTSD parents (NPTSD), and 50 healthy subjects underwent resting-state functional MRI. The whole-brain functional network was constructed by thresholding partial correlation matrices of 90 brain regions. Group differences in the topological properties, the diagnosis-by-sex interaction, and the relationships between topological metrics and clinical variables were investigated.<bold>Results: </bold>Compared with healthy subjects, PTSD and NPTSD groups exhibited significantly shorter path lengths and higher nodal centralities in many brain regions across sexes; however, no significant difference was found between the PTSD and NPTSD groups. Additionally, the global topological metrics did not show any sex difference, whereas the nodal centralities in the left insula, right inferior frontal gyrus, and right posterior cingulate cortex differed significantly only in women, and the nodal centralities in the bilateral anterior cingulate cortices and left hippocampus were significantly different only in men. Furthermore, the nodal centralities of the right parahippocampus demonstrated significant diagnosis-by-sex interaction.<bold>Limitation: </bold>Cross-sectional design of this study could not demonstrate the causality.<bold>Conclusions: </bold>The parents who lost their only child exhibited a shift toward randomization and significant nodal topological alterations independent of PTSD effects. Additionally, sex differences were observed primarily in the topological properties at the nodal level, which may indicate a neurobiological contribution to the greater incidence of PTSD in females. [ABSTRACT FROM AUTHOR]