Perceived control attenuates the relationship between experiences of discrimination and left amygdala volume in older adults

Abstract

AbstractBackgroundThe medial temporal lobes (MTLs), which exhibit neuropathology in Alzheimer’s disease (AD), are modulated by experience. Animal models of environmental enrichment and chronic stress have shown structural plasticity in the amygdalae and hippocampi. Experiences of discrimination (EoD; e.g., sexism, racism, ageism) are salient chronic psychosocial stressors that affect physical and mental health. Perceived control, one’s perception of environmental and psychological control, may attenuate the impact of EoD by increasing resilience. Although aberrant amygdala activity has been implicated in relation to EoD, research has yet to investigate the structural correlates of EoD.MethodsData from 36 participants (58% female, 55‐86 years, 31% African American) were used to investigate the moderating effect of perceived control on EoD and MTL volume. T1‐weighted MR images were captured on a 3T Philips Achieva scanner and analyzed using FreeSurfer's automatic segmentation protocol. Models were adjusted for age, sex, education, and intracranial volume.ResultsMultiple regression models showed an association between left (t(30) = ‐4.073, p < 0.001) and right (t(30) = ‐2.116, p < 0.05) amygdala, but not hippocampal, volume and EoD scores. Additionally, perceived control significantly interacted with EoD for the left (b = 10.66, t(28) = 2.776, p < 0.01), but not right (b = 2.096, t(28) = 0.514, p > 0.05), amygdala. At lower levels of perceived control, higher EoD (b = ‐108.57, t(28) = ‐4.509, p < 0.001) predicted smaller left amygdala volume. However, EoD (b = ‐11.77, t(28) = ‐0.562, p = 0.58) did not predict left amygdala volume at higher levels of perceived control.ConclusionThis cross‐sectional study of cognitively healthy, older adults, provided evidence that greater EoD was associated with smaller amygdala volumes bilaterally. Further, participants with lower perceived control at higher levels of EoD showed a greater reduction in left, but not right, amygdala volume. This suggests that the interaction between chronic stress and resilience might contribute to neuropathology or reserve of AD‐sensitive regions, specifically in populations that face higher discriminatory experiences. Future studies are needed to examine whether interventions that increase perceived control (resilience) have beneficial effects on neural structure and function.