Does zip code contribute to racial health disparities in aging?
Isabel Yannatos was the lead author on this study. They studied racial disparities in aging, examining how the external environment is internalized to influence health outcomes among Black and White Americans. Currently, they are pursuing a career in health policy to move towards health equity.
or technically,
Contributions of neighborhood social environment and air pollution exposure to Black-White disparities in epigenetic aging
[See Original Abstract on Pubmed]
Isabel Yannatos, Shana Stites, Rebecca Brown, Corey McMillan
What’s the first thing that comes to mind when you think of health? A doctor’s office? A waiting room? A pharmacy? Whatever image you conjured, your house and your surrounding neighborhood probably didn’t make the cut, but the environments in which we live, work, and age are actually huge determinants of our health.
These “environments” encompass not just the environment in a traditional sense (exposure to severe weather or air pollution), but also the social (violence/crime, sense of community, and wealth) and physical (walkability or access to green spaces) elements of your neighborhood. All of these factors play a critical role in how healthy you are and how well you age [1]. However, all environments aren’t created equally, and long-standing racism and exclusionary policies directly influence how these important health determinants, like access to healthy food or exposure to pollutants, are distributed.
For instance, it is well established that Black Americans have fewer socioeconomic resources and higher exposure to unhealthy conditions in their neighborhoods [2]. In turn, these environments create and cement a number of racial health inequities such as increased prevalence of age-related diseases, like Alzheimer’s [1-3]. This disparity in aging is not due to genetic differences, rather to differences in socioeconomic risk factors, inadequate healthcare access (e.g., decreased management of conditions like high blood pressure and diabetes), and the cumulative impact of social stress and political marginalization [3].
Motivated to further understand how neighborhood discrimination influences health and aging, former Neuroscience Graduate Group (NGG) student Dr. Isabel Yannatos and colleagues from the Bioinformatics in Neurodegenerative Disease lab leveraged a large (2,960 participants!) dataset collected by the National Institute on Aging. This Health and Retirement Study consisted of phone or in-person surveys collected from a representative population of Americans 50 years and older.
In addition to filling out these surveys, which asked individuals about their race/ethnicity, age, and social and physical environment, a subset of participants gave a blood sample for measurement of DNA methylation. Methylation is a process by which the body adds little chemical tags to specific parts of DNA molecules. Typically, these methylation tags prevent part of the DNA molecule from being used by the body. This to say, methylation can change the activity of the DNA molecule without changing the DNA sequence. Accumulating DNA methylation tags is a normal part of aging. It’s one way our bodies -- and our DNA -- change as we get older. In fact, scientists can use the pattern of methylation present on a person’s DNA to calculate their biological age. The difference between this biological age (e.g., DNA methylation-based age) and chronological age (e.g., the number of years someone has been alive) is one way to measure the pace at which someone is aging [4]. If biological age comes out to be higher than chronological age, it’s a sign that the body is aging more quickly than expected.
Isabel and colleagues used measures of DNA methylation to calculate a biological age for each participant. They found that Black participants appeared biologically older than White participants of the same chronological age, suggesting that Black Americans are aging more quickly than their White counterparts. Could this difference in aging between Black and White Americans be due to racial disparities in neighborhood environments? Using survey responses and additional data on air pollution from the Environmental Protection Agency, Isabel concluded that the Black Americans surveyed had lower neighborhood socioeconomic resources, higher levels of social deprivation, and increased exposure to fine particulate matter (PM2.5, the same pollutant given off by wildfire smoke). Moreover, these factors did contribute to the difference in DNA methylation-based age between Black and White participants, suggesting that neighborhood discrimination and deprivation are associated with accelerated aging among Black Americans.
Interestingly, Isabel found differences not only in the amount of PM2.5 exposure between Black and White participants, but also in the extent to which this exposure to air pollution affected aging. In particular, analysis revealed that Black individuals appeared more vulnerable to the effects of air pollution. This increased vulnerability was a result of fewer socioeconomic resources, which impacts things like the proximity to major sources of pollution and the quality of air filtration available. In other words, the neighborhood environments of Black participants not only put them at a higher risk for exposure, but also made them more susceptible to exposure’s damaging effects.
This study has numerous important implications. For one, Isabel’s work provides evidence that working to eliminate the racial gaps in neighborhood social and economic conditions would go a long way toward alleviating the accelerated biological aging and increased vulnerability to environmental exposure present among Black Americans. It also highlights just how important information about neighborhood conditions can be for health and aging, inviting future exploration of how local environments contribute to our health across the lifespan.
About the brief writer: Kara McGaughey
Kara is a PhD candidate in Josh Gold’s lab studying how we make decisions in the face of uncertainty and instability. Combining electrophysiology and computational modeling, she’s investigating the neural mechanisms underlying this adaptive behavior.
Citations:
Diez Roux, A. V. (2016). Neighborhoods and Health: What Do We Know? What Should We Do? American Journal of Public Health, 106(3), 430–431. https://doi.org/10.2105/AJPH.2016.303064
Tessum, C. W., Apte, J. S., Goodkind, A. L., Muller, N. Z., Mullins, K. A., Paolella, D. A., Polasky, S., Springer, N. P., Thakrar, S. K., Marshall, J. D., & Hill, J. D. (2019). Inequity in consumption of goods and services adds to racial–ethnic disparities in air pollution exposure. Proceedings of the National Academy of Sciences, 116(13), 6001–6006. https://doi.org/10.1073/pnas.1818859116
Lennon, J. C., Aita, S. L., Bene, V. A. D., Rhoads, T., Resch, Z. J., Eloi, J. M., & Walker, K. A. (2022). Black and White individuals differ in dementia prevalence, risk factors, and symptomatic presentation. Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, 18(8), 1461–1471. https://doi.org/10.1002/alz.12509
Diez Roux, A. V. (2016). Neighborhoods and Health: What Do We Know? What Should We Do? American Journal of Public Health, 106(3), 430–431.https://doi.org/10.2105/AJPH.2016.303064