Nearly half of the mortality gap between Black and white adults can be traced to the cumulative toll of a lifetime of stress and heightened inflammation, a new study published Monday shows.
The study, published in JAMA Network Open, bolsters the body of evidence showing that chronic stress takes a biological toll that shortens lives.
“It’s important to be empirically demonstrated,” said Ryan Bogdan, the study’s senior author and a professor of psychological and brain sciences at Washington University in St. Louis. Researchers tracked the prevalence of two proteins linked to inflammation in the body and tied it to enduring discrimination and related social challenges. The measurement captures more comprehensively “the aftermath” of stressful events, he said.
Researchers analyzed the proteins in the blood in more than 1,500 Black and white adults who were part of an aging study in the St. Louis area spanning 17 years. They found that decades of stress — childhood adversity, trauma, discrimination, and economic hardship — were associated with higher levels of inflammation later in life, which correlated with earlier death.
Epidemiologists say the two biomarkers — C-reactive protein and interleukin-6 — tend to linger in the blood after the body’s fight-or-flight system has been repeatedly triggered, allowing them to capture what’s accumulated over time.
The study, which was largely driven by Washington University in St. Louis graduate student Isaiah Spears, supports the “weathering hypothesis,” which posits that biological wear and tear is caused by striving to overcome hardships in an unequal society.
Over the course of the study, 25% of Black participants died compared with about 12% of white participants, the study found, meaning Black participants were more likely to die at younger ages. Researchers found that 49.3% of this gap was explained by stress and inflammation.
A likely undercount
Arline T. Geronimus, a professor and population health equity researcher at the University of Michigan who began conceptualizing the weathering hypothesis 40 years ago and was not involved in this study, said the data likely represents an undercount. Study participants, on average, were in their late 50s when the study began and were then followed into their 70s and 80s.
“The most-weathered have already died,” Geronimus said, noting that age span 35 to 60 is “the hardest, most stressful period of life for marginalized groups.”
She added that another limitation of the study was that the researchers used the “neon lights” of stress events, capturing major traumas or overt discrimination, while overlooking a quieter and important aspect of weathering — the daily stress of resilience. That includes microaggressions, or routine slights, and code-switching, the constant effort to adjust speech or behavior to fit into predominantly white workplaces. Over time, she said, suppressing anger or frustration to avoid reinforcing stereotypes can take a real physiological toll.
“It’s not just about trauma or severe deprivation, but kind of everyday fists in the face,” she said. It’s a limitation the study acknowledged.
Black Americans have among the shortest life spans in the United States with a life expectancy of 74 years in 2023, according to federal figures. White Americans live longer on average, but still fewer years than Asian Americans, who have the highest life expectancy — about 85 years, federal data shows.
Linda Sprague Martinez, a professor and health equity researcher who was not involved in the study, said people tend to misunderstand the type of stress that weathers a body and the interventions needed for relief.
“Stress management class is not going to solve this problem,” said Sprague Martinez, who runs the Health Disparities Institute at UConn Health in Connecticut. She called the new study’s core finding, that nearly 50% of the mortality gap is linked to stress, “striking.”
“This is important evidence that continues to contribute to what we know about the fact that racism drives racial inequities,” she said.
She added that this type of research has been targeted for elimination by the Trump administration because it is associated with diversity, equity, and inclusion, or DEI.
“There are people who’d be happy if we stopped doing our work, but no,” she said. “We still have to keep doing the work.”
Health equity experts said the paper is unlikely to influence policy, in part because it does not pinpoint specific forms of structural racism — such as redlining, police violence, income inequality, school segregation, or historical racial terror such as lynching and cross-burning — that drive health disparities.
“Concentrated poverty, the wealth gap, homeownership — they didn’t talk about any of these and how it affects folks who are aging,” said Derek M. Griffith, university professor of health equity and population health at the University of Pennsylvania’s nursing and medical schools, who was not involved in the study.
The field of health equity has found collectively that analyzing biomarkers that signal inflammation is one accurate way of measuring the effects of stress on the body.
“The fact that they’ve found a big relationship with that combination of those measures is novel,” he said. “The fact that they found that relationship, is not.”
