Structural inequities contribute to racial/ethnic differences in neurophysiological tone, but not threat reactivity, after trauma exposure

Abstract

Considerable racial/ethnic disparities persist in exposure to life stressors and socioeconomic resources that can directly affect threat neurocircuitry, particularly the amygdala, that partially mediates susceptibility to adverse posttraumatic outcomes. Limited work to date, however, has investigated potential racial/ethnic variability in amygdala reactivity or connectivity that may in turn be related to outcomes such as post-traumatic stress disorder (PTSD). Participants from the AURORA study (n = 283), a multisite longitudinal study of trauma outcomes, completed functional magnetic resonance imaging and psychophysiology within approximately two-weeks of trauma exposure. Seed-based amygdala connectivity and amygdala reactivity during passive viewing of fearful and neutral faces were assessed during fMRI. Physiological activity was assessed during Pavlovian threat conditioning. Participants also reported the severity of posttraumatic symptoms 3 and 6 months after trauma. Black individuals showed lower baseline skin conductance levels and startle compared to White individuals, but no differences were observed in physiological reactions to threat. Further, Hispanic and Black participants showed greater amygdala connectivity to regions including the dorsolateral prefrontal cortex (PFC), dorsal anterior cingulate cortex, insula, and cerebellum compared to White participants. No differences were observed in amygdala reactivity to threat. Amygdala connectivity was associated with 3-month PTSD symptoms, but the associations differed by racial/ethnic group and were partly driven by group differences in structural inequities. The present findings suggest variability in tonic neurophysiological arousal in the early aftermath of trauma between racial/ethnic groups, driven by structural inequality, impacts neural processes that mediate susceptibility to later PTSD symptoms.

Neighborhood Disadvantage and Neural Correlates of Threat and Reward Processing in Survivors of Recent Trauma

“…However, trauma exposure may have been associated with potentiated amygdala reactivity and obscured outcomes associated with neighborhood disadvantage. AURORA analyses in 2023 did not observe between-group differences in reactivity during the fearful faces task among survivors of recent trauma when stratified by prior sexual trauma or by ethnoracial group with differing levels of neighborhood disadvantage . However, differences in amygdala intrinsic connectivity by ethnoracial group were mediated by differential exposure to neighborhood disadvantage .…”

“…This study is reported following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline. The included neuroimaging data have been previously reported, but these analyses are unique …”

“…The included neuroimaging data have been previously reported, but these analyses are unique. 17,24,25 To retain the largest sample size, participants were not required to have completed both tasks (see eFigure 1 in Supplement 1 for study flowchart). Participants were included in the threat and reward sample if they had useable functional magnetic resonance imaging (fMRI) during the respective task, T1-weighted images, and diffusion tensor imaging (DTI) data.…”

“…In the US, Black and Hispanic individuals are disproportionately exposed to neighborhood disadvantage compared with White individuals, a disparity that was created and is maintained by structural racism . In survivors of recent trauma, neighborhood disadvantage helped explain differences by race and ethnicity in amygdala resting-state connectivity with regions involved in threat processing (eg, the insula) . Prior work found that Black youths living in more disadvantaged neighborhoods showed greater activity in the anterior cingulate cortex (ACC) in response to social threat compared with White youths .…”

Neighborhood Perceptions Are Associated With Intrinsic Amygdala Activity and Resting-State Connectivity With Salience Network Nodes Among Older Adults

“…These covariates were selected owing to their potential confounding role with either the exposure or the outcome. For example, prior studies have shown that less favorable neighborhood conditions disproportionately impact minoritized racial and ethnic groups (3), and research has also demonstrated that racial discrimination relates to amygdala activity and FC (15,16) and these neural patterns vary by racial and ethnic group (20). Study participants completed the Beck Depression Inventory (BDI-II) (32) and the Beck Anxiety Inventory (BAI) (33) for subjective measures of depressive and anxiety symptoms, respectively.…”