PTSD symptoms, loneliness, and amygdala volumes during pandemic social distancing associated with risk of suicidal ideation in trauma survivors with and without pre-pandemic PTSD

• Pandemic PTSD symptoms associated with loneliness and perceived burdensomeness • Pandemic left amygdala and its nuclei volumes negatively correlated with thwarted belongingness and loneliness • Pre-existing PTSD diagnosis associated with higher perceived burdensomeness • Pre-existing PTSD diagnosis associated with smaller right amygdala and its centromedial nuclei post pandemic The prolonged social distancing during the COVID-19 pandemic has been shown to worsen loneliness, posttraumatic stress disorder (PTSD) symptoms and suicidal thought, though the negative effects of COVID-19 pandemic-related isolation on survivors with previous traumatic experiences remain largely unexplored. The present study investigated how pandemic-related social isolation relates to PTSD symptoms, thwarted belongingness and perceived burdensomeness, loneliness, and amygdala volumes in pre-pandemic trauma survivors with and without PTSD diagnosis. Sixty-two participants from a previous PTSD study were recruited during the pandemic to complete online surveys, including the Interpersonal Needs Questionnaire (INQ) for thwarted belongingness (INQ-TB) and perceived burdensomeness (INQ-PB) to assess perceived social isolation and risk of suicidal ideation, UCLA Loneliness Scale, and the PTSD Checklist-5 (PCL) for PTSD symptoms, the virtual PTSD diagnostic interview, and a structural MRI (sMRI) scan to measure amygdala and nuclei volumes. Pre-pandemic PTSD diagnosis record was also obtained. Pandemic PCL were positively associated with UCLA-Loneliness and INQ-PB scores. INQ-TB and UCLA-Loneliness scores were inversely associated with post-pandemic amygdala volumes, specifically in left basolateral, central and cortical nuclei. Pre-pandemic PTSD diagnosis was associated with higher INQ-PB scores and smaller volumes of right amygdala and its centromedial nuclei post pandemic. These findings suggest severe PTSD symptoms and smaller amygdala were associated with high loneliness and potential risk of suicidal ideation during the COVID-19 pandemic in trauma survivors. Pre-pandemic PTSD diagnosis can predict potential risk of suicidal ideation and reduced amygdala and its nuclei volumes when individuals are exposed to further stress.