Experiences of Discrimination Are Associated With Greater Resting Amygdala Activity and Functional Connectivity

Abstract

Background: Social discrimination, a type of psychological stressor, is associated with poorer physical and mental health outcomes, yet we have little understanding of how discrimination affects neural functions in marginalized populations. By contrast, the effects of psychological stress on neural functions are well documented, with evidence of significant effects on the amygdala-a neural region that is central to psychosocial functions. Accordingly, we conducted an examination of the relation between self-reported discrimination exposure and amygdala activity in a diverse sample of adults.

Methods: Seventy-four adults (43% women; 72% African American; 23% Hispanic; 32% homosexual/bisexual) completed self-report ratings of discrimination exposure. Spontaneous amygdala activity and functional connectivity were assessed during resting-state functional magnetic resonance imaging.

Results: Greater discrimination exposure was associated with higher levels of spontaneous amygdala activity. Increases in discrimination were also associated with stronger functional connectivity between the amygdala and several neural regions (e.g., anterior insula, putamen, caudate, anterior cingulate, medial frontal gyrus), with the most robust effects observed in the thalamus. These effects were independent of several demographic (e.g., race, ethnicity, sex) and psychological (e.g., current stress, depression, anxiety) factors.

Conclusions: Collectively, our findings provide the first evidence that social discrimination is independently associated with elevations in intrinsic amygdala activity and functional connectivity, thus revealing clear parallels between the neural substrates of discrimination and psychological stressors of other origins. Such results should spur future investigations of amygdala-based networks as potential etiological factors linking discrimination exposure to adverse physical and mental health outcomes.

Keywords: Amygdala; Psychosocial stressors; Social discrimination; Social marginalization; Stress; Thalamus.

Conflict of interest statement

Financial Disclosures

All authors reported no biomedical financial interests or potential conflicts of interest.

Copyright © 2018 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Association between spontaneous left amygdala activity (at rest) and self-reported discrimination exposure. fALFF = fractional amplitudes of low frequency fluctuation; EDS = Everyday Discrimination Scale. *p<.05 controlling for right amygdala activity current levels of depression stress anxiety and ptsd-related symptoms.>

Figure 2

A. Regions where left amygdala functional connectivity strength is associated with discrimination exposure (EDS scores) (p<.05 fwe corrected one sagittal image left coronal right and axial images are shown. for the x="8;" y="−16;" begin at z="−29" increase in increments. b. association between self-reported discrimination exposure mean amygdala connectivity strengths within clusters shown panel a. eds="Everyday" scale error r="right." controlling current levels of depression stress anxiety ptsd-related symptoms.>