Assessing the role of socioeconomic status and discrimination exposure for racial disparities in inflammation

Connectome modeling of discrimination exposure: Impact on your social brain and psychological symptoms

Discrimination is a social stressor that is associated with adverse health outcomes, but the underlying neural mechanisms remain unclear. The fusiform, including the fusiform face area (FFA) plays a critical role in face perception especially regarding hostile faces during discrimination exposure; and are key regions involved in social cognition. We compared resting-state spontaneous activity and connectivity of the fusiform and FFA, between 153 individuals (110 women) with high (N = 73) and low (N = 80) levels of discrimination (measured by the Everyday Discrimination Scale) and evaluated the relationships of these brain signatures with psychological outcomes and stress-related neurotransmitters. Discrimination-related group differences showed altered fusiform signal fluctuation dynamics (Hurst exponent) and connectivity. These alterations predicted discrimination experiences and correlated with anxiety, depression, and cognitive difficulties. A molecular architecture analysis using cross-modal spatial correlation of brain signatures and nuclear imaging derived estimates of stress-related neurotransmitters demonstrated overlap between discrimination-related connectivity and dopamine, serotonin, gamma-aminobutyric acid (GABA), and acetylcholine. Discrimination exposure associated with alterations in the fusiform and face processing area may reflect enhanced baseline preparedness and vigilance towards facial stimuli and decreased top-down regulation of potential threats. These brain alterations may contribute to increased vulnerability for the development of mental health symptoms, demonstrating clinical relevance of social cognition in stressful interpersonal relationships.

Differences in inflammation among black and white individuals: A systematic review and meta-analysis

IMPORTANCE

Despite persisting health disparities between Black and White individuals, racial differences in inflammation have yet to be comprehensively examined.

OBJECTIVE

To determine if significant differences in circulating levels of inflammatory markers between Black and White populations exist.

DATA SOURCES

Studies were identified through systematic searches of four electronic databases in January 2022. Additional studies were identified via reference lists and e-mail contact.

STUDY SELECTION

Eligible studies included full-text empirical articles that consisted of Black and White individuals and reported statistics for inflammatory markers for each racial group. Of the 1368 potentially eligible studies, 84 (6.6 %) representing more than one million participants met study selection criteria.

DATA EXTRACTION AND SYNTHESIS

Risk of bias was assessed via meta regressions that considered relevant covariates. Data heterogeneity was tested using both the Cochrane Q-statistic and the standard I2 index. Random effects models were used to calculate estimates of effect size from standardized mean differences.

MAIN OUTCOMES AND MEASURES

Outcome measures included 12 inflammatory markers, including C-reactive protein (CRP), Fibrinogen, Interleukin-6 (IL-6), Tumor necrosis factor-alpha (TNF-α), and soluble intercellular adhesion molecule 1 (sICAM-1).

RESULTS

Several markers had robust sample sizes for analysis, including CRP (White N = 934,594; Black N = 55,234), Fibrinogen (White N = 80,880; Black N = 18,001), and IL-6 (White N = 20,269; Black N = 14,675). Initial results indicated significant effects on CRP (k = 56, pooled Hedges' g = 0.24), IL-6 (k = 33, g = 0.15), and Fibrinogen (k = 19, g = 0.49), with Black individuals showing higher levels. Results also indicated significant effects on sICAM-1 (k = 6, g = -0.46), and Interleukin-10 (k = 4, g = -0.18), with White individuals showing higher levels. Sensitivity analyses confirmed robust effects for CRP, IL-6, Fibrinogen, and sICAM-1 while also revealing significant effects on TNF-α (k = 18, g = -0.17) and Interleukin-8 (k = 5, g = -0.19), with White individuals showing higher levels of both.

CONCLUSIONS AND RELEVANCE

Current meta-analytic results provide evidence for marked racial differences in common circulating inflammatory markers and illustrate the complexity of the inflammatory profile differences between Black and White individuals. Review Pre-Registration: PROSPERO Identifier - CRD42022312352.

From Discrimination to Disease: The Role of Inflammation

ABSTRACT

Discrimination is an established social determinant of mental health that contributes to psychiatric illness disparities among marginalized populations. There is emerging research elucidating the biological mechanisms connecting discrimination to mental health outcomes, revealing inflammation as a key pathway. This column synthesizes evidence from existing literature on the links between discrimination and inflammation, and outlines both the opportunities and challenges in this field. The discussion highlights the necessity of a multifaceted approach to address discrimination, and thus, reduce inflammation at both individual and population levels.

The dynamic and reciprocal relationship between perceived everyday discrimination and cognitive function in later life

OBJECTIVES

This study, based on socioemotional selectivity theory and cognitive theory, investigates the dynamic and reciprocal relationship between perceived discrimination and cognitive function in later life.

METHODS

Data were drawn from four waves of the Health and Retirement Study (HRS 2006, 2010, 2014, and 2018). A total of 4,125 people who were 51 and older were included. Cognitive function was measured by the telephone interview for cognitive status (TICS-27). Perceived discrimination was measured using scores of the perceived everyday discrimination scale. Random intercept cross-lagged panel model (RI-CLPM) was utilized. The model was adjusted for a range of covariates. Subgroup analysis by ethnoracial groups was conducted.

RESULTS

Cross-sectionally, while lower cognitive function was associated with higher perceived discrimination, this relationship was unidirectional. Longitudinally, higher perceived discrimination predicted lower cognitive function in later waves only among non-Hispanic White individuals.

CONCLUSION

Results suggested that a decline in cognitive function may precede and contribute to the worsening of perceived discrimination, which may result in further decline in cognitive function. Lifetime experience of discrimination was discussed as a possible source of the racial/ethnic variations in the relationship. Further study is needed to examine whether this relationship holds among people with cognitive impairment and dementia.

Chronic Work Discrimination, Allostatic Load, and HbA1c in Older Workers

BACKGROUND AND OBJECTIVE

Work discrimination is an important public health problem with consequences for health. This study examined the effect of chronic work discrimination on 4-year changes in HbA1c, as a reflection of glucose control and type 2 diabetes risk in older workers and assessed whether allostatic load (AL) affected the strength of this association.

RESEARCH DESIGN AND METHODS

We used Health and Retirement Study data (2010-2016, n = 3,246). Conditional change multinomial logistic regression examined the association between chronic work discrimination, high AL (4 or more out of 8 high-risk biomarkers), and HbA1c, while accounting for relevant covariates.

RESULTS

Black participants had the highest rates of baseline (22.7%) and follow-up (28%) HbA1c levels, AL (38%), and chronic work discrimination (39%; p < .01). Severe chronic work discrimination was associated with elevated HbA1c (relative risk ratio [RRR] = 1.61, 95% confidence interval [CI] = 1.07, 2.43). AL was associated with elevated HbA1c (RRR = 1.49, 95% CI = 1.04, 2.14). Relative to White participants, Hispanic (RRR = 1.52, 95% CI = 1.07, 2.16, RRR = 1.81, 95% CI = 1.051, 3.12), and Black (RRR = 2.42, 95% CI = 1.82, 3.23; RRR = 3.00, 95% CI = 1.97, 4.56) participants had an increased risk of intermediate and elevated HbA1c, respectively. Among those with long job tenure (≥5 years), both moderate (RRR = 1.81, 95% CI = 1.11, 2.96) and severe (RRR = 1.90, 95% CI = 1.15, 3.12) chronic work discrimination was associated with elevated HbA1c.

DISCUSSION AND IMPLICATIONS

Chronic work discrimination was associated with HbA1c; however, no moderating effects of AL were observed. Findings underscore a need for organizational and public health measures to establish strong anti-discrimination laws in the workplace to improve the work environment of older workers and reduce diabetes risk.

Discrimination and Cardiovascular Health in Black Americans: Exploring Inflammation as a Mechanism and Perceived Control as a Protective Factor

OBJECTIVE

Inflammation may be an integral physiological mechanism through which discrimination impacts cardiovascular health and contributes to racial health disparities. Limited research has examined psychosocial factors that protect against the negative effects of discrimination on inflammation. Perceived control is a promising possible protective factor, given that it has been shown to moderate the relationship between other psychosocial stressors and physiological outcomes. This study thus tested whether systemic inflammation mediated the link between discrimination and cardiovascular health and whether perceived control moderated this relationship.

METHODS

Data for this project included 347 non-Hispanic/Latinx Black adults (mean [standard deviation] age = 51.64 [11.24] years; 33% female) taken from the Midlife in the United States study. Perceived control and daily discrimination were assessed via self-report, and inflammation was measured via circulating levels of C-reactive protein (CRP), interleukin-6 (IL-6), fibrinogen, and tumor necrosis factor α. Cardiovascular health was measured by morbidity of cardiovascular conditions: heart disease, hypertension, and/or stroke.

RESULTS

CRP (indirect effect: b = 0.004, 95% confidence interval [CI] = 0.001-0.007) and fibrinogen (indirect effect: b = 0.002, 95% CI = 0.0003-0.005) mediated the link between discrimination and cardiovascular conditions. Perceived control moderated the relationship between discrimination and CRP ( F (1, 293) = 4.58, Δ R2 = 0.013, b = -0.02, SE = 0.01, p = .033). CRP mediated the link between discrimination and cardiovascular conditions only for those who reported low levels of perceived control (Index = -0.003, 95% CI = -0.007 to -0.0001).

CONCLUSION

Findings provide empirical evidence of inflammation as a mechanism linking discrimination to cardiovascular conditions among Black Americans. Additionally, perceived control may be protective. Findings could suggest beliefs about control as a potential intervention target to help reduce the negative effects of discrimination on cardiovascular health among Black Americans.

Incident racial discrimination predicts elevated C-Reactive protein in the Black Women's experiences Living with Lupus (BeWELL) study

INTRODUCTION

Racial discrimination is a distinct health threat that increases disease risk among Black Americans. Psychosocial stress may compromise health through inflammatory mechanisms. This study examines incident experiences of racial discrimination and changes in the inflammatory biomarker C-reactive protein (CRP) over a two-year period among Black women with systemic lupus erythematosus (SLE)-an inflammatory autoimmune disease sensitive to psychosocial stress and characterized by stark racial inequities in outcomes.

METHODS

Data are from the Black Women's Experiences Living with Lupus (BeWELL) Study. Participants (n = 380) from metropolitan Atlanta, Georgia were enrolled from April 2015 to May 2017. Incident racial discrimination was assessed bi-annually via self-report using the Experiences of Discrimination measure. CRP was assessed annually over a two-year period. Latent change score analyses modeled longitudinal within-person associations between incident racial discrimination and change in log-transformed CRP from baseline to Year 2.

RESULTS

Incident experiences of racial discrimination were associated with elevated log-CRP across the two-year study period (b = 0.039, SE = 0.017, 95% CI: 0.006, 0.071). For each domain of incident racial discrimination experienced, CRP increased 3.98%.

CONCLUSION

This study contributes to growing evidence on the biological consequences of racism and is the first to document an association between incident racial discrimination and changes in inflammation among Black women with SLE. Racial inequities in SLE outcomes and other diseases driven by inflammatory pathways may be explained in part through experiences of racial discrimination.

How Discrimination Gets Under the Skin: Biological Determinants of Discrimination Associated With Dysregulation of the Brain-Gut Microbiome System and Psychological Symptoms

BACKGROUND

Discrimination is associated with negative health outcomes as mediated in part by chronic stress, but a full understanding of the biological pathways is lacking. Here we investigate the effects of discrimination involved in dysregulating the brain-gut microbiome (BGM) system.

METHODS

A total of 154 participants underwent brain magnetic resonance imaging to measure functional connectivity. Fecal samples were obtained for 16S ribosomal RNA profiling and fecal metabolites and serum for inflammatory markers, along with questionnaires. The Everyday Discrimination Scale was administered to measure chronic and routine experiences of unfair treatment. A sparse partial least squares-discriminant analysis was conducted to predict BGM alterations as a function of discrimination, controlling for sex, age, body mass index, and diet. Associations between discrimination-related BGM alterations and psychological variables were assessed using a tripartite analysis.

RESULTS

Discrimination was associated with anxiety, depression, and visceral sensitivity. Discrimination was associated with alterations of brain networks related to emotion, cognition and self-perception, and structural and functional changes in the gut microbiome. BGM discrimination-related associations varied by race/ethnicity. Among Black and Hispanic individuals, discrimination led to brain network changes consistent with psychological coping and increased systemic inflammation. For White individuals, discrimination was related to anxiety but not inflammation, while for Asian individuals, the patterns suggest possible somatization and behavioral (e.g., dietary) responses to discrimination.

CONCLUSIONS

Discrimination is attributed to changes in the BGM system more skewed toward inflammation, threat response, emotional arousal, and psychological symptoms. By integrating diverse lines of research, our results demonstrate evidence that may explain how discrimination contributes to health inequalities.

Racial Differences in C-Reactive Protein, Depression Symptoms, and Social Relationships in Older Adults: A Moderated Network Analysis

INTRODUCTION

We introduce moderated network analysis as an integrative approach to assess the moderation effects of race on the relationship between C-reactive protein (CRP) and depression symptoms in older adults. This study further explores how the observed relationships differ adjusting for social relationships.

METHODS

This secondary analysis of cross-sectional data from the National Social Life, Health, and Aging Project (2010-2011) includes 2,880 older adults. We used different depression symptom domains (depressed affect, low positive affect, somatic symptoms, and interpersonal problems) from the Center for Epidemiologic Studies-Depression Scale. Social relationships were assessed with measures of social integration, social support, and social strain. The moderated networks were constructed using the R-package mgm. The racial moderator was coded as White/African American racial groups.

RESULTS

In the moderated networks of CRP and depression symptoms, CRP-"interpersonal problems" edge was present only among African Americans. CRP-"somatic symptoms" edge was present in both racial groups with equal edge weights. After adjusting for social relationships, the aforementioned patterns remained the same, but the edge weights were attenuated. We additionally observed CRP-social strain and social integration-"depressed affect" edges only in African Americans.

DISCUSSION

Race may moderate the relationship between the CRP and depression symptoms in older adults and social relationships might be important covariates to consider while analyzing them. This study as an initiation point; future network investigations would benefit from leveraging more contemporary cohorts of older adults, gaining a large sample size with diverse racial/ethnic backgrounds, and important covariates. Several important methodological issues of the current study are addressed.