Does discrimination cause harm to the body?

By Priyanjana Pramanik, MSc.May 16 2024Reviewed by Benedette Cuffari, M.Sc.

In a recent study published in Brain, Behavior, & Immunity - Health, researchers investigate whether experiencing discrimination is associated with accelerated biological processes of aging.

Study: Multi-discrimination exposure and biological aging: Results from the midlife in the United States study. Image Credit: Dragana Gordic / Shutterstock.com

The health impact of discrimination

Discrimination, whether based on weight, sex, or race, exerts profound adverse effects on health outcomes ranging from hypertension, cardiovascular disease, psychological distress, depression, suicidal ideation, and mortality. Some researchers have hypothesized that discrimination could lead to chronic activation of stress responses.

The ‘biological weathering’ hypothesis suggests that, due to persistent exposure to psychosocial stress, people facing discrimination might experience accelerated aging that makes them more susceptible to illness and premature death. There is strong empirical evidence for this hypothesis, as several studies have reported that aging-related diseases develop in Black Americans at younger ages and that disparities across a broad range of aging-related conditions between Black and White populations increase with age.

These associations might be attributed to behavioral pathways such as smoking and obesity. However, little is known about the specific biological mechanisms that cause discrimination to have wide-ranging effects on disease development.

About the study

Deoxyribonucleic acid (DNA) methylation (DNAm) markers can be used to study the biological impacts of the social environment. Moreover, DNAm is directly affected by environmental chemical exposure and indirectly affected by behaviors and stress responses.

DNAm also responds to the aging process, as several related biomarkers have been used to predict age and are known as ‘clocks.’ The current study used these epigenetic clocks to explore the associations between workplace, major, and everyday discrimination and biological aging, in addition to the role of body mass index (BMI) and smoking as mediators in this relationship.

Researchers hypothesized that the greater the exposure to discrimination, the faster an individual ages biologically. They also tested the hypothesis that Black individuals exhibit more pronounced associations than White participants.

Participants were recruited as part of the Study of Midlife in the United States (MIDUS) and underwent comprehensive assessments that covered psychosocial, behavioral, and sociodemographic factors before biomarker assessment. Whole blood sampling was used to generate DNAm profiles.

Biological aging was assessed through epigenetic clocks that estimated the progress and pace of biological aging from the DNAm states of white blood cells. Workplace, major, and everyday discrimination was evaluated using questionnaires, with higher scores indicating higher exposures to discrimination.

Covariates included race, age, sex, education, and employment status, whereas smoking and BMI were included as mediators. Discrimination scores were regressed on the epigenetic clocks, adjusted for covariates, and stratified by race.

Study findings

The study sample included 1,967 individuals with an average age of 53, 55% of whom were women. Over 80% of the study cohort were White, whereas the remainder were Black.

Over 75% of the study cohort had attended college, and nearly 70% were employed. The average everyday, workplace, and major discrimination scores were 13.01, 10.87, and 1.15, respectively.

After adjusting for sex and age, higher everyday, workplace, and major discrimination scores were associated with accelerated biological aging based on the epigenetic clocks. The significant correlations between clocks and discrimination scores remained after adjusting for education and race for some but not all clocks.

Adjusting for BMI and smoking status reduced some associations to below statistical significance levels. Stratified analyses suggested that there are positive associations between biological aging and everyday and major discrimination for White participants with no or weak relationships for Black individuals.

Conclusions

The study findings indicate that midlife adults who report higher exposure to discrimination may age faster and exhibit greater biological age. Major and everyday discrimination showed stronger associations with biological aging than workplace discrimination.

Nearly half of these correlations were accounted for by BMI and smoking behavior, thus providing important insights into the mechanisms that underly the effect of discrimination on biological aging. However, discrimination exposure may also trigger other physiological responses, such as cortisol release and poor sleep.

Notably, the association between biological aging and discrimination was more pronounced for White as compared to Black participants. This may be because Black Americans face higher levels of discrimination overall and may have developed coping strategies that make them more resilient.

Nevertheless, the study findings should be validated using other aging biomarkers. Another limitation of the current study is that it relies on self-reported exposure to discrimination and focuses on discrimination at the individual level rather than the community level.

Future studies should also include individuals of other races and ethnic subgroups, as well as consider fluctuations in discrimination, which is not stable over the lifetime, rather than assessing it at a single point.