Longitudinal changes in brain structure and their relationship with subclinical psychiatric symptoms in parents who lost their only child in China

Background: Losing an only child (Shidu) is a grievous traumatic event that may affect brain structure, even if it does not lead to psychiatric disorders. However, longitudinal changes in brain structure and their relationship to subclinical psychiatric symptoms (SPS) have not been well investigated in Shidu parents without any psychiatric disorders (SDNP). Objectives: This study aimed to investigate cross-sectional and longitudinal changes in cortical thickness and surface area in SDNP, and to explore their relationship with SPS. Methods: A total of 50 SDNP and 40 matched healthy controls (HC) were enrolled. All participants underwent structural MRI scans and clinical assessment at baseline and at the 5-year follow-up. Differences in brain structural phenotypes (cortical thickness, surface area, and their annual rate of change) between the SDNP and HC groups were compared using FreeSurfer. Correlations between significant brain structural phenotypes and SPS in the SDNP group were evaluated using multiple linear regressions. Results: The SDNP group showed a smaller surface area in the left inferior parietal cortex than the HC group at baseline and follow-up. The SDNP group showed slower rates of cortical thinning and surface area loss in several brain regions than the HC group from baseline to follow-up. Moreover, slower rates of cortical thinning in the left insula, superior frontal cortex, and superior temporal cortex were associated with greater reductions in avoidance, depression, and trauma re-experiencing symptoms scores over time in the SDNP group, respectively. Conclusions: Shidu trauma-induced structural abnormalities in the inferior parietal cortex may persist over time and be independent of the severity of psychiatric symptoms. The expansion of prefrontal, temporal, and insular cortex implicated in emotional regulation may contribute to improvements in psychiatric symptoms in Shidu parents.