Recent research indicates that Americans residing in underprivileged communities are at a markedly increased risk of developing dementia.
Researchers from Wake Forest University in North Carolina analyzed health information from over 600 participants involved in the university’s brain study. These individuals underwent blood tests and brain scans, and their data was associated with geographic information derived from their home addresses.
The investigation revealed a link between living in disadvantaged neighborhoods, assessed through a ‘social vulnerability index’ that evaluates areas based on factors such as poverty, unemployment, and lack of community support, and brain changes tied to dementia. This correlation was particularly significant among Black participants.
Residents of lower-income neighborhoods with limited access to health resources exhibited tangible alterations in brain structure.
Individuals from these areas displayed thinner cortical layers, changes in white matter indicative of blood vessel diseases, reduced cerebral blood flow, and inconsistent circulation.
These findings imply that the brain is not receiving the steady and high-quality blood supply necessary for optimal survival and function.
These issues are largely driven by the same factors that define these neighborhoods. People tend to have limited access to healthy food, fewer opportunities for safe physical activity and chronic stress from financial strain and a lack of community health resources.
All of these conditions can lead to untreated high blood pressure and diabetes, which silently damage the blood vessels supplying the brain. Over time, this reduced and inconsistent blood flow can cause the brain to atrophy, contributing to the onset of dementia.
New research from Wake Forest University confirms a link between socioeconomic disadvantage and higher dementia risk, following similar recent findings from Cambridge University (stock)
The brain uses approximately a quarter of the body’s oxygen and blood supply, despite accounting for only two percent of its weight.
When this supply is compromised, brain cells are damaged and eventually die, which can result in such severe cognitive decline as to warrant a dementia diagnosis.
Sudarshan Krishnamurthy, a sixth-year MD-PhD candidate at Wake Forest University and lead author of the US study, said in a statement: ‘This study is one of the first to connect a variety of place-based social factors with advanced biological markers of dementia.
‘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 study included 679 North Carolinians with an average age of 70, participating in the Wake Forest Brain Study.
Most of them were white females, though men made up 34 percent of the study population.
Living in the most disadvantaged, poorest neighborhoods was found to cause a literal loss of brain cells in the areas critical for memory and thinking.
Furthermore, active regions of the brain were not receiving the oxygenated blood they needed, and waste products were not being cleared effectively.
This directly damages brain cells, allowing toxins like amyloid to accumulate.
Dr Timothy Hughes, a professor of geriatric medicine at Wake Forest University School of Medicine and senior author, said: ‘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.’
After collecting blood sample data and brain scans and cross-referencing results with location codes corresponding with North Carolina residents’ addresses, researchers generated composite scores to measure neighborhood-level disadvantage, vulnerability, and environmental injustice.
The indices took into account poverty, education level, employment status, the quality of housing, such as lack of plumbing and median home value.
The study used three separate tools to measure neighborhood challenges, and on every one, Black participants lived in significantly more disadvantaged areas.
In the first tool, a score of 50 meant the neighborhood is at the national average. A score of 80 meant the neighborhood is more disadvantaged than 80 percent of all US neighborhoods.
A score of 20 meant it is more disadvantaged than only 20 percent of neighborhoods, meaning it is among the least underprivileged areas.
This disparity was clearest with the Area Deprivation Index, the first tool. A higher score indicates that people have less access to healthy food, safe parks for exercise, and quality healthcare. This leads to higher rates of hypertension, diabetes and obesity, all major risk factors for dementia.
Black residents, on average, lived in neighborhoods with a disadvantage score of 72.1, meaning their communities were more disadvantaged than 72 percent of neighborhoods nationwide.
White participants, with an average score of 51.5, indicated that they lived in neighborhoods near the national average.
Another scoring tool, the Social Vulnerability Index, researchers looked at measuring people’s social support where they live and how the lack thereof can lead to chronic stress and chronically high cortisol levels. Over time, stress causes inflammation throughout the body, a known risk factor for neurological disease.
The third tool, the Environmental Justice Index, measured direct physical damage from air pollution and toxic chemicals, which are known to cause brain inflammation and accelerate the accumulation of Alzheimer’s proteins, such as amyloid.
While the study didn’t provide specific average scores for the Social Vulnerability and Environmental Justice indices, it confirmed that Black participants faced significantly higher levels of these place-based risks, creating a cumulative burden on their brain health.
The scores are powerful predictors because they encapsulate the real-world conditions that, over years and decades, physically erode the brain’s structure and function, making dementia a far more likely outcome.
The finding that these damaging brain changes were only seen in Black participants, even after adjusting for individual cardiometabolic health, suggests that the cumulative burden of systemic and structural racism, captured by neighborhood-by-neighborhood scores, is itself a direct and independent risk factor for dementia.
While older Black Americans are twice as likely as older Whites to have Alzheimer’s or another dementia, research hasn’t yet identified the cause.
The Wake Forest study was published in the journal Alzheimer’s & Dementia.
A team of scientists at Cambridge University in the UK added weight to the Wake Forest findings in a study published about two weeks later, in which they reported that in underprivileged neighborhoods, daily stressors like crime, unsafe housing and poor environmental conditions create a chronic strain.
This harms key cognitive skills, including processing speed and attention, which are often the first to decline due to vascular brain issues.
