More adverse childhood experiences are associated with increased social thinning and severe psychological distress.

Adverse childhood experiences have been linked to psychopathology due to reduced social networks or social thinning. However, evidence of the temporal associations between adverse childhood experiences, social networks, and psychopathology was lacking, as few studies assessed social networks repeatedly. Further, their underlying neurocognitive and biological mechanisms related to hypervigilance and inflammation remain unclear. This study aimed to clarify these associations using a three-wave population-based cohort study during the COVID-19 pandemic (n = 465), where we leveraged repeated social network assessments. Self-reported questionnaires assessed adverse childhood experiences, social network size and diversity, psychological distress, and hypervigilance regarding COVID-19. Blood tests were conducted to measure inflammation markers. Individuals with more adverse childhood experiences demonstrated lesser increases in their social networks than those without adverse childhood experiences. Decreased network sizes were associated with severe psychological distress, but this association did not remain after adjusting for baseline distress. On the other hand, reduced network diversities were associated with increased psychological distress. We did not find any paths through hypervigilance regarding COVID-19 and inflammation that explain associations between adverse childhood experiences, social thinning, and psychological distress. These findings emphasize the significant social network changes in the associations between adverse childhood experiences and psychopathology.