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Summary: New research shows that neighborhood conditions—from pollution and housing to economic opportunities—can directly affect brain health and dementia risk. By analyzing brain scans and biomarkers of 679 adults, scientists found that people living in areas with greater social and environmental disadvantage showed signs of reduced brain thickness, altered blood flow and changes in white matter.
These biological differences were most pronounced among black participants from highly burdened neighborhoods. The findings highlight that brain health is not only determined by genetics and lifestyle, but also by the broader environment and social systems in which we live.
Key facts:
Neighborhood effects: Higher neighborhood disadvantage scores were linked to brain changes linked to dementia risk. Biological evidence: Alterations in brain structure, reduced blood flow and vascular changes were observed in people from high-load areas. Implications for equity: Results show social and environmental inequality
Source: Wake Forest University
Conditions where you live can influence your brain health and risk of dementia, according to a new study from Wake Forest University School of Medicine.
The study, published today in Alzheimer’s & Dementia: Behavior & Socioeconomics of Aging, a journal of the Alzheimer’s Association, found that people living in neighborhoods with higher levels of social vulnerability, environmental injustice, and socioeconomic disadvantage showed measurable differences in brain structure and function.
“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, Ph.D., associate professor of gerontology and geriatric medicine at Wake Forest University School of Medicine and senior author.
The researchers analyzed data from 679 adults enrolled in the Healthy Brain Study at the Wake Forest Alzheimer’s Disease Research Center. Each participant underwent brain scans and blood tests to detect early signs of Alzheimer’s disease and related dementias.
The team then compared these results to three national-level tools that assess neighborhood conditions at the postcode level: the Area Deprivation Index, the Social Vulnerability Index and the Environmental Justice Index.
Higher scores on these indices, reflecting greater burden of social determinants of health in neighborhoods, were associated with changes in dementia-related biomarkers, especially among black participants whose neighborhoods experienced the greatest burden of social determinants.
These dementia-related biomarkers included a thinner outer layer of the brain, white matter changes representing vascular diseases, reduced blood flow, and more uneven circulation, all of which can contribute to memory and cognitive decline over time.
“This study is one of the first to connect a variety of place-based social factors with advanced biomarkers of dementia,” said Sudarshan Krishnamurthy, sixth-year MD-Ph.D. candidate and lead author.
“It demonstrates that the conditions and environment in which people live – such as access to clean air, safe housing, nutritious food and economic opportunities – can leave a lasting imprint on brain health.”
The study contributes to a growing body of evidence that social and environmental factors are not just background influences, but are critical to understanding and addressing Alzheimer’s disease and related dementias.
Krishnamurthy emphasized the political relevance of the findings.
“If we truly want to improve brain health in all communities, we must look beyond individual choices and focus on the broader systems and structures that shape health at the neighborhood level.”
Funding: This research was supported by grants F30 AG085932 and P30 AG07294 from the National Institutes of Health; and American Heart Association grant 24PRE1200264.
Key questions answered:
A: Neighborhoods with higher levels of social vulnerability, pollution and poverty were linked to measurable differences in brain structure and circulation that increase the risk of dementia.
A: He is one of the first to directly connect environmental and social disadvantage to biological markers of dementia, showing that inequality is literally imprinted in the brain.
A: Addressing systemic inequalities (such as housing, environmental justice, and access to nutritious food and health care) could help reduce the risk of dementia in all populations.
About this research news on dementia and brain health
Author: Myra Wright
Source: Wake Forest University
Contact: Myra Wright – Wake Forest University
Image: Image is credited to Neuroscience News.
Original research: Open access.
“Associations of place-based social determinants of health with biomarkers of Alzheimer’s disease and related dementias” by Timothy Hughes et al. Alzheimer’s and dementia: behavior and socioeconomics of aging
Abstract
Associations of place-based social determinants of health with biomarkers of Alzheimer’s disease and related dementias
INTRODUCTION
Relationships between place-based social determinants of health (SDoH) and Alzheimer’s disease and related dementia biomarkers are emerging.
METHODS
Linear regressions examined associations of area deprivation index (ADI), social vulnerability index (SVI), and environmental justice index (EJI) with biomarkers among Healthy Brain Study participants (n = 679), stratified by racialized groups. Neuroimaging biomarkers included cortical thickness, brain parenchyma volume, white matter hyperintensity volume, cerebral blood flow (CBF), and their variability in gray matter. Plasma biomarkers included glial fibrillary acidic protein (GFAP), amyloid beta ratios, and phosphorylated tau 181.
RESULTS
Place-based SDoH measures were higher in Black participants compared to White participants. Among black participants, we found relationships between higher SVI and EJI with greater CBF variability, higher IDA with lower mean CBF, and higher ADI and SVI with lower cortical thickness.
DISCUSSION
Place-based SDoH may partially capture the effects of structural racism on brain health and affirm the importance of structural interventions to address SDoH.
