Sonia Ruiz

A new study by researchers at Yale, the National Institutes of Health, Stanford and UCLA found that black and less-educated older women experience an accelerated aging process.

The team found that among a group of postmenopausal women, non-Hispanic blacks and those with less education exhibited higher epigenetic or biological aging, which partially accounted for their shorter life expectancies. Epigenetic aging is independent of chronological aging and describes how old one’s body is compared to one’s actual age. Led by Yale pathology professor Morgan Levine, the research was published Feb. 6 in the journal Psychoneuroendocrinology.

“It’s pretty well established that on average, black people experience reduced life expectancy due to socioeconomic factors,” Levine said. “We found that about 16 percent of the racial and ethnic disparities in life expectancy can be explained by epigenetic measures, and about 12 percent of the difference can be explained by education, which is a proxy for socioeconomic status.”

The study builds on previous research on the links between stress, socioeconomic status and epigenetic aging as well as on the hypothesis that socioeconomic disadvantage causes accelerated aging, which in turn reduces life expectancy. The team developed a new epigenetic aging measure to determine whether higher epigenetic aging among less-educated or minority individuals accounts for observed shorter life expectancy in a sample of U.S. postmenopausal women.

The team found that non-Hispanic blacks and those with low education exhibited the greatest risk of mortality. Non-Hispanic whites were 0.6 years younger than what was expected based on their chronological ages, while non-Hispanic blacks and Hispanics were 0.6 years and 0.4 years older, respectively. Women with less than a high school education were 1.4 years older than expected, while women with a college education were 1.0 years younger.

The pattern of lower education and higher epigenetic aging held for non-Hispanic whites and Hispanics as well. Among non-Hispanic blacks, however, epigenetic age did not drop with increasing education.

This was unexpected, said Zuyun Liu, a postdoctoral associate at the Yale School of Medicine and first author of the paper. Literature review suggests that this exception may be explained by the low quality of education accessible for black women, increased discrimination and psychosocial stressors, as well as inadequate social resources in higher education, Liu said. He added that this may raise some concerns about related education policies.

Levine explained that measuring epigenetic aging could help develop a preventive, not reactionary, approach to health. Instead of treating a disease after it happens, researchers can identify beforehand which groups of people are aging faster than normal, investigate the factors contributing to these disparities and mitigate them. Various therapies that target aging are currently in development, including senolytic drugs — which combat age-related diseases — as well as dietary and behavioral interventions, Levine said.

“In general, stress-related differences in aging biology tend to show up early in life, sometimes even at birth. We don’t know when these differences started. They could also be cumulative through life. The chronicity of the stress of being racialized and being exposed to discrimination, inequality and social disadvantages should not be underestimated,” said Elissa Epel, a psychiatry professor at the University of California, San Francisco, who was not involved in the research.

Epel also emphasized the importance of understanding sex differences in aging. This study suggests that low education is particular a vulnerability factor for women, she said. Women with low education are exposed to greater lifespan stressors that can impact their reproductive lifespans, the duration of their exposure to estrogen — which influences risk of breast cancer — and their risk for premature onset of diseases.

After this study, researchers who have been trying to determine why disparities exist, apart from causes associated with socioeconomic status, now have at least one more mechanistic explanation for why some people live longer than others, said S. Jay Olshansky, a professor in the School of Public Health at the University of Illinois at Chicago who was not involved in the research. There is much more to unpack going forward, he added.

In 2016, life expectancy for the U.S. population was 78.6 years, and the difference in life expectancy between the non-Hispanic white and non-Hispanic black populations was 3.7 years, according to the National Center for Health Statistics.

Eui Young Kim | euiyoung.kim@yale.edu