Can segregated neighborhoods change people’s genes?

Researchers know that African-Americans get sicker and die earlier than white people—and now, a University of Michigan researcher will study whether racial segregation plays a part by changing a person’s genes.

Margaret Hicken, director of the U-M Racism Lab at the Institute for Social Research, has won a $3.6 million grant from the National Institute on Minority Health and Health Disparities to examine inequalities in healthy aging between black and white people in the United States. The grant is a continuation of the Americans’ Changing Lives study, which has followed the same group of people in neighborhoods across the country for more than 30 years.

Hicken’s grant will add an important component: It will collect genetic material from the study participants to examine how the participants’ neighborhoods impact the regulation of their genes.

Through racial segregation, whites and blacks are often sorted into segregated neighborhoods. Black neighborhoods, then, are often exposed to greater levels of chemical stressors. These chemical stressors intersect with other kinds of stressors in black people’s lives to greatly impact their health.

The Americans’ Changing Lives study collects self-reported health information from its nationally representative participants every five years. Hicken’s grant will add a sixth wave of data collection as well as blood collection for DNA analysis. She hopes to understand how environmental exposure to pollution as well as other social stressors could impact these participants’ genes, a field called epigenetics.

“We have their reports of chronic disease, and their reports of mental health, but no physical measure. Can we track health or disease even before it becomes clinically obvious?” said Hicken, also a research assistant professor at the U-M Medical School. “One important way to understand the role of the social and the built environment is to understand what’s going on molecularly.”

The grant builds upon the knowledge that black and Hispanic neighborhoods are often located near pollution-producing factories or disposal sites—sites that often move in after the neighborhood has already become established.

University of Michigan environmental researcher Paul Mohai and colleagues published a study in which they surveyed polluters, and found that race was the main determinant predictor of where these places were sited, Hicken said. In another study, they found that these neighborhoods were there first and the polluters came after.

Kelly Bakulski, a co-investigator on the grant, will study the underlying biological mechanisms of these health disparities. Bakulski, a research assistant professor at the U-M School of Public Health, specializes in epigenetic epidemiology.

The field of epigenetics studies impacts—both environmental and social—to our bodies that result in changes in gene activity that can be passed down through generations. These changes in gene activity, called DNA methylation, don’t alter a person’s DNA sequence, but can cause changes in the way genes operate.

“All of the cells in your body have the same DNA sequence but the way we get specialized cells—a skin cell versus a neuron—requires these marks, or epigenetics, on top of the DNA sequence,” Bakulski said. “Epigenetics are part of our development, part of our basic biology, and some of those marks can be sensitive to environmental factors.”

These sensitivities can be expressed in subtle ways, Bakulski said. Researchers have previously identified epigenetic changes in the cord blood of babies born to mothers who smoke.

“Very often it’s in subtle ways. It’s not like we’re changing these marks so much that a neuron looks like a skin cell. These are small numbers of marks affected,” she said. “But we’ve noticed that epigenetics are sensitive to toxicants as well as nonchemical stressors like social factors and stress.”

Through the study, Hicken and her team plan to examine the associations between DNA methylation, chemical stressors, nonchemical stressors and racial segregation. First, they plan to study whether neighborhood racial segregation is associated with epigenetic change, then whether there’s an association between this kind of change and exposure to chemical and nonchemical stressors, and finally whether there’s an association between DNA methylation and key genetic markers for healthy aging.

This grant is funded under number 1R01MD013299.

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