A new study suggests that where a person lives can be linked to their brain health and potential risk for dementia. Researchers found that individuals residing in neighborhoods with greater social, economic, and environmental challenges showed measurable differences in their brain structure and function. The findings were published in Alzheimer’s & Dementia: Behavior & Socioeconomics of Aging, a journal of the Alzheimer’s Association.
Scientists have long documented that Black and other minority communities experience higher rates of Alzheimer’s disease. Many researchers believe these disparities are not explained by biology alone but are influenced by social and structural factors, often called the social determinants of health.
These determinants are the conditions in which people are born, grow, work, live, and age. While previous studies have connected neighborhood conditions to memory and thinking skills, few have examined the direct biological links to brain changes seen in imaging scans and blood tests.
A team of researchers led by Sudarshan Krishnamurthy at Wake Forest University School of Medicine sought to fill this gap. They aimed to understand if living in a disadvantaged area was associated with the physical markers of brain health related to Alzheimer’s disease and related dementias. They wanted to see if factors like poverty, environmental pollution, and social vulnerability left a tangible imprint on the brain. This approach moves beyond cognitive test scores to explore the underlying biology.
The investigation involved 679 adults aged 54 and older who were part of the Wake Forest Alzheimer’s Disease Research Center Healthy Brain Study. The group included 157 participants who identified as Black or African American and 522 who identified as White.
The researchers linked each participant’s home address to three different national databases that measure neighborhood-level challenges. These included the Area Deprivation Index, which assesses factors like poverty, education, housing quality, and employment. They also used the Social Vulnerability Index, which measures a community’s preparedness to handle disasters and includes data on socioeconomic status, household characteristics, and transportation access. The third measure was the Environmental Justice Index, which adds environmental burdens like air and water pollution and proximity to hazardous sites.
Each participant also underwent a series of health assessments. Magnetic resonance imaging scans were used to get a detailed look at their brain structure and function. The scientists measured the thickness of the cortex, which is the brain’s outer layer responsible for higher-level thinking. They also examined the volume of white matter hyperintensities, which are small areas of damage often linked to vascular problems.
In addition, they assessed cerebral blood flow, or how much blood is reaching different parts of the brain. The team also collected blood samples to measure the levels of plasma biomarkers, which are proteins associated with the development of Alzheimer’s disease.
The analysis first revealed that, on average, the Black participants in the study lived in neighborhoods with significantly higher levels of disadvantage, social vulnerability, and environmental injustice compared to the White participants.
When the researchers looked for connections between these neighborhood scores and brain health, they found a distinct pattern. Among Black participants, living in an area with greater disadvantage was associated with poorer neuroimaging outcomes. Specifically, higher scores on the neighborhood indices were linked to a thinner cortex in brain regions vulnerable to Alzheimer’s disease. These participants also showed less uniform blood flow in the brain’s gray matter.
These associations were not observed among the White participants. Even after the researchers accounted for individual health factors like blood pressure, cholesterol, and diabetes through a cardiometabolic index, the link between neighborhood conditions and brain imaging markers in Black participants remained. The findings suggest that the environment where one lives may have a distinct impact on brain health that is independent of some personal health metrics.
“This study is consistent with other research showing that the state of the social environment in which people live can shape their brain health in profound ways,” said Timothy Hughes, an associate professor of gerontology and geriatric medicine at Wake Forest University School of Medicine and the study’s senior author.
This work builds on previous research that has found similar connections. For example, another recent study published in Alzheimer’s & Dementia showed that women in midlife who lived in neighborhoods with high concentrated poverty experienced faster memory decline, with the sharpest decline seen among Black women. The Wake Forest study adds a critical layer to this by connecting neighborhood factors not just to cognitive performance but to the underlying biological changes in the brain itself.
“This study is one of the first to connect a variety of place-based social factors with advanced biological markers of dementia,” said Krishnamurthy, a sixth-year M.D.-Ph.D. candidate and lead author. “It shows that the conditions and environment in which people live, such as access to clean air, safe housing, nutritious food and economic opportunity, may leave a lasting imprint on brain health.”
The researchers note that the place-based measures used in the study may partially capture the effects of structural racism. The inequitable distribution of resources, opportunities, and environmental hazards across neighborhoods often falls along racial lines, creating disparities in health outcomes. The study contributes to a growing body of evidence that social and environmental factors are not just background influences but are central to understanding and addressing Alzheimer’s disease and related dementias.
Krishnamurthy emphasized the policy relevance of the findings. “If we truly want to improve brain health across all communities, we must look beyond individual choices and hone in on the broader systems and structures that shape health at the neighborhood level.”
The study does have some limitations. Because the data was collected at a single point in time, it cannot prove that neighborhood conditions cause brain changes, only that they are associated. The study also did not include participants from other racial and ethnic groups, such as Hispanic or Asian American communities, where these factors may have different effects. Finally, the researchers did not have information on how long each participant had lived in their respective neighborhood, which could influence the level of exposure to these environmental factors.
Future research is needed to confirm these findings in larger, more diverse populations over longer periods. Such studies could help to illustrate the origins of disparities in Alzheimer’s outcomes and identify specific interventions. The authors suggest that both grassroots initiatives and policy efforts aimed at improving neighborhood conditions may be effective strategies for promoting better brain health and reducing dementia risk for everyone.
The study, “Associations of place-based social determinants of health with biomarkers of Alzheimer’s disease and related dementias,” was authored by Sudarshan Krishnamurthy, Lingyi Lu, Marc D. Rudolph, Melissa Rundle, Courtney Sutphen, Thomas C. Register, Xiaoyan I. Leng, Sarah A. Gaussoin, Megan Lipford, Da Ma, Allison Caban-Holt, Goldie S. Byrd, Laura D. Baker, Samuel N. Lockhart, Suzanne Craft, James R. Bateman, and Timothy M. Hughes.
