Racism may accelerate aging on a genetic level, study finds

BY Rebecca Jacobson  January 15, 2014 at 2:51 PM EDT
Photo by Ann Hermes / The Christian Science Monitor

Jovan Washington, left, Cecil Boyce and Louis Estrada were interviewed in 2012 in New Haven, Conn., where they talked about the negative stereotypes attached to young African-American men. A new study shows a link between experiencing discrimination and accelerated aging in black men. Photo by Ann Hermes / The Christian Science Monitor

Can experiencing discrimination lead to premature aging? Researchers think there could be a connection.

According the Centers for Disease Control, African-American men die six to seven years earlier than white men. But no one is exactly sure why. David H. Chae, a social epidemiologist at the University of Maryland School of Public Health, thinks the psycho-social strain of discrimination may explain the disparity.

“We can all relate to how the experience of being treated unfairly impacts us physiologically,” he said. “There’s a cascade of biochemical reactions. Your heart rate rises, your muscles clench.” Dealing with prejudice — and all its effects on your life — is inherently stressful, he said, and that may lead to accelerated aging.

Chae and his colleagues published a study in the American Journal of Preventive Medicine last week, that looked at 92 African-American men between the ages of 30 and 50 to determine if racism might be one of the culprits behind premature aging.

To understand your biological age, biochemists examine telomeres, repetitive sequences of DNA at the ends of our chromosomes. Specifically, Chae and his colleagues looked at telomere length from leukocytes, or white blood cells, an indicator of general systemic aging.

Telomeres are like the plastic caps on your shoelaces, said Rita Effros, professor of pathology at University of California Los Angeles. When cells divide and DNA replicates, it can’t quite copy the ends of the chromosomes, she said. Telomeres keep your chromosomes intact, she said, but over time they shorten, losing 50 to 100 base pairs a year. A newborn baby’s telomeres may have 12,000 base pairs, but by the time he is 80 years old, his telomeres may be as short as 5,000 base pairs.

“[Telomeres] keep wearing down gradually until it all unravels,” said Dr. Lisbeth Nielsen, at the National Institute of Aging, part of the National Institute of Health. That eventually leads to cell death, she said.

But if it gets too short, that “unraveling” means the cell dies leaving the body vulnerable to a host of age-related diseases like diabetes, cancer and Alzheimers. A telomere’s truncated length is an indicator that something is wrong, Effros said.

“When telomeres get critically short, the cell stops being able to divide,” she said. And if an immune cell, which protects your body from infections, needs to divide, but can’t? That’s when you’ve got a problem, Effros said.

And recent studies have found that telomeres can be shortened by cortisol, the hormone released when a person undergoes stress. Think of being cut off in traffic, narrowly avoiding an accident, Chae said. Your heart rate rises and your muscles contract, but once the danger is over, you calm down.

Scientists are finding that the cortisol your body produced under stress takes a significant toll on your cells.

Could the constant stress of dealing with discrimination change the way the body functions? To find out, Chae and his colleagues asked African-American men about a gamut of racial discrimination in their lives. Some reported harassment from police, discrimination in the workplace or extra scrutiny while shopping, for example. Other men reported never experiencing racial prejudice.

But what was important was how these men internalized those experiences, Chae said. They used a computerized tool called the black-white implicit association test to measure how these men viewed their own race, showing either an “anti-black bias” or a “pro-black bias.”

Chae found that men who experienced more frequent discrimination and internalized an anti-black bias had shorter telomeres than men who faced prejudice and still had positive views of their race. Even when controlling for other factors — chronologic age, socioeconomic status, overall health — those who internalized the experience were one to three years older biologically than those who had not.

The study has limitations. For one thing, it’s small. Larger studies are needed, said Nancy Krieger, a social epidemiologist at the Harvard School of Public Health and Chae’s former advisor.

And telomere lengths measured here aren’t “critically short,” Effros said, especially compared to the decade worth of shortening, for example, that an immune disease like HIV can produce. But, she added, if these men continue being stressed, their telomeres could get to that critically short length.

Also, numerous factors contribute to the shorter lifespan of African-American men, like poverty and how it affects access to healthcare or nutrition. But Krieger thinks that studies like this one make the connection between socioeconomic disparities and our health.

“This is part of biological pathway that translates social adversity into poor health,” Krieger said.