A new peer-reviewed study offers one of the clearest examinations yet of why Black Americans continue to die earlier than their white counterparts, pointing not to biology, but to the cumulative weight of stress carried across a lifetime.
Researchers writing in JAMA Network Open analyzed nearly two decades of data from more than 1,500 adults in the St. Louis region and found that Black participants experienced significantly shorter survival times than white participants, even when measured across the same age range.
The study tracked participants from late middle age into older adulthood, examining how lifelong exposure to stress and inflammation intersect with mortality.
The findings accentuate “the continued need for preventions, interventions, and policies that limit stress exposure and its potential impacts on health to reduce mortality risk as well as mortality disparities between Black and white populations in the U.S.,” the study’s authors wrote.
The cohort included 505 Black adults and 1,049 white adults, all of whom were followed for up to 17 years. By the end of the study period, 25.3% of Black participants had died, compared with 11.9% of white participants. Researchers found that Black participants not only faced higher mortality rates but also reported higher levels of cumulative stress across their lives and higher levels of inflammatory markers later in life.
Stress was assessed using multiple measures spanning different life experiences, accounting for childhood maltreatment, lifetime trauma, verified stressful life events, experiences of discrimination, and socioeconomic factors such as income and education. Inflammation was assessed through blood markers including C-reactive protein and interleukin-6, both of which are associated with chronic disease and aging.
Taken together, cumulative stress and inflammation accounted for nearly half of the observed racial gap in mortality. The researchers determined that these factors explained 49.3% of the difference in survival time between Black and white participants, even after adjusting for age and sex. Higher stress levels were associated with higher inflammation, which in turn was linked to earlier death.
Arline Geronimus, a University of Michigan professor who developed the weathering theory and was not involved in the research, said the findings likely understate the full scope of the problem.
“The most weathered have already died,” Geronimus said, according to U.S. News & World Report.
She described ages 35 to 60 as “the hardest, most stressful period of life for marginalized groups.”
Importantly, the findings did not attribute disparities to race itself. Instead, the study emphasized that unequal exposure to stressors tied to discrimination and socioeconomic conditions plays a central role.
While stress and inflammation explained a substantial portion of the mortality gap, more than half of the difference remained unexplained, pointing to additional factors such as environmental exposure, access to care, and long-term social conditions.
The authors cautioned that the study focused on one metropolitan area and that patterns may vary across regions. Still, they noted that the results align with longstanding research showing that chronic stress accumulates over time and takes a measurable toll on health.
“Cumulative lifespan stress and inflammation accounted for a large portion of the increased mortality risk among Black individuals,” study authors concluded.