Prior Experiences of Racial Discrimination Impact Acute Resting-State Connectivity of the BNST as a Predictor of PTSD in Black Adults

Abstract

Altered resting-state activity of the bed nucleus of the stria terminalis (BNST) – which mediates anxious arousal and threat monitoring – is implicated in the etiology of posttraumatic stress disorder (PTSD). Experiences of racial discrimination can also increase one’s risk for developing PTSD by eliciting chronic states of hypervigilance, which impair essential resting-state processes related to fear extinction. Considering the frequency in which Black Americans experience racial discrimination, the current study investigated acute BNST resting-state functional connectivity as a predictor of future PTSD symptoms, as well as the impact of racial discrimination on the BNST as a predictor of PTSD. Black adults (N = 95) who experienced a traumatic injury were recruited from the emergency department. Data was collected at two time points: (1) two-weeks post-trauma, where participants underwent a resting-state fMRI scan, and their baseline PTSD symptoms and history of racial discrimination were assessed; (2) six-months post-trauma, where their PTSD symptoms were reassessed. Results indicated that two-week BNST resting-state connectivity prospectively predicted PTSD symptoms six-months post-trauma. Additionally, prior experiences of racial discrimination moderated the relationship between acute BNST resting-state connectivity and future PTSD symptoms. Thus, in the acute aftermath of a traumatic event, resting-state connectivity of the BNST could be a useful biomarker of risk for PTSD in Black Americans, particularly for individuals who have experienced more racial discrimination throughout their lifetime.