You Are Where You Live
Miller School research confirms other studies that found physical and mental health have a direct correlation to your ZIP code
By Bob Woods
Illustration by hitandrun
Animation by Michael DiMilo
Contributions by Charlotte Schubert, Ph.D. and Richard Westlund
T
urns out, you’re not just what you eat. Whether you live in downtown Miami, the Chicago suburbs, the Texas Hill Country or anywhere else across the nation, your address can impact your health and longevity.
A growing body of research — including recent studies of Alzheimer’s disease and breast cancer conducted by Miller School investigators — shows that the local environment in which you live, work and play directly influences critical factors such as access to clean air and water, quality health care, safe housing, reliable transportation, green spaces, healthy food, good schools, job opportunities and physical activities. Improving those place-based factors, often referred to as social determinants of health, can help eliminate the risks of developing a variety of physical and mental diseases and disorders.
The Robert Wood Johnson Foundation, a national philanthropy focused on improving health, estimated that one in five Americans live in neighborhoods with high rates of crime, pollution, inadequate housing, lack of jobs and limited access to nutritious food. Those adverse social determinants can increase the incidence of infant mortality, heart disease and lower life expectancy. Conversely, simply having steady employment allows people to afford a well-balanced diet, decent health care and stable housing.
There are pros and cons, health-wise, when it comes to living in urban, suburban or rural areas. Cities, for example, generally offer wider access to health care facilities and services though also have higher levels of pollution, which can contribute to respiratory and cardiovascular diseases. Suburbs provide a balance of amenities, crime rates and green spaces yet fewer health care options and greater reliance on cars, which can reduce physical activity and contribute to sedentary lifestyles. Rural communities are less polluted, have easier access to outdoor activities and tend to have stronger support networks, but access to health care can be poor, leading to higher mortality rates and lower life expectancy.
While the wide-open spaces in rural areas and leafy suburbs may have an abundance of healthy greenery, cities can offer plenty of good-for-you verdancy, too. Indeed, a new study by public health researchers at the Miller School determined that older adults living on green blocks in Miami-Dade County have a lower incidence of Alzheimer’s disease than those in less green surroundings.
‘Precision Greenness’
“We have coined the phrase ‘precision greenness’ to emphasize the importance of trees, shrubs and other ground cover on local blocks,” said Scott Brown, Ph.D., research associate professor of public health sciences at the Miller School and senior author of the study.
The precision greenness study of 230,738 U.S. Medicare beneficiaries compared older adults living in consistently high greenness Census blocks from 2011 to 2016 with those living in consistently low greenness blocks from 2011 to 2016. Those living in the highest third of greenness had 16% lower odds of developing Alzheimer’s disease compared with those in the lowest third of greenness, adjusting for age, sex, race, ethnicity and neighborhood income.
“This adds weight to our team’s prior research on the multiple health benefits of living in greener communities,” Dr. Brown said. “It suggests that planting trees or other green interventions could reduce Alzheimer’s disease risk both at individual and population levels.”
“Planting trees or other green interventions could reduce Alzheimer’s disease risk both at individual and population levels.”
That earlier research showed that a higher level of neighborhood greenness can decrease the risk for 13 chronic conditions. “Since we started these studies a decade ago, I have been stunned by the power of greenness in aging and chronic disease,” said the new study’s co-author, José Szapocznik, Ph.D., professor and chair emeritus of the Department of Public Health Sciences and director of the University of Miami’s Public Health Policy Lab. “If planting trees and preserving the existing canopy can reduce the incidence of Alzheimer’s disease, stroke, diabetes and other conditions, the payoff for communities around the world will be huge.”
Dr. Szapocznik said there are multiple reasons why greenness could improve health, including increased physical activity, greater social connectedness, improved sleep and a reduction in air pollution. “When you look outside and see greenery, your stress levels are reduced, a particularly important consideration in lower-income neighborhoods, where residents are impacted by chronic stress,” he said. “Clearly, greenness is important for health, as well as for neighborhood beauty. Many cities around the world have tree-planting initiatives for climate change or beautification, and our team has shown there is a positive impact on public health as well.”
Breast Cancer Mortality
Miller School researchers have also compared communities throughout the country to assess mortality rates among breast cancer patients. According to socioeconomic data from a recent nationwide study, those from disadvantaged neighborhoods face a 40% higher risk of dying than patients from advantaged, wealthier neighborhoods. Factors included median household income, home value, education and percentage of residents who were working class or unemployed. The dataset — pulled from 21 geographic areas, representing 36.7% of the U.S. population — dovetails with similar research results, published last year, from breast cancer patients in the Miami area.
The Miami study ruled out a major contribution from air pollution, said Neha Goel, M.D., M.P.H., a surgeon-scientist and social epidemiologist at Sylvester Comprehensive Cancer Center, who led both studies. But there may be other environmental factors, such as exposure to toxins from contaminated sites, that could play a role, she speculated. “Even after controlling for multiple other variables, women living in disadvantaged neighborhoods still have disparate survival outcomes,” Dr. Goel said.
Ultimately, people often choose where to live based on factors that on the surface may not be related to better health. Single adults just out of college, for instance, might want to live in a city for certain job opportunities. Young families may want to be near good schools. Retirees might move to where their children and grandchildren live. Regardless, as evidence-based correlations between where you call home and its relative healthiness continue to grow, there’s ample food for thought to be considered. 
